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Blood donor screening: Medical history

Blood donor screening: Medical history
Author:
Steven Kleinman, MD
Section Editor:
Aaron Tobian, MD, PhD
Deputy Editor:
Jennifer S Tirnauer, MD
Literature review current through: Dec 2022. | This topic last updated: Dec 05, 2022.

INTRODUCTION — A major goal of transfusion medicine practice is to reduce the risk of infectious and non-infectious complications of blood component or whole blood transfusion. Obtaining a medical and behavioral history from prospective blood donors is one of the first steps in this process.

This topic reviews the blood donor medical history. Other protections are discussed separately:

Protections for the donor – (See "Blood donor screening: Overview of recipient and donor protections", section on 'Pre-donation procedures and processes' and "Blood donor screening: Overview of recipient and donor protections", section on 'Protection of the donor'.)

Laboratory testing of donated blood – (See "Blood donor screening: Laboratory testing".)

During the coronavirus disease 2019 (COVID-19) pandemic, the US Food and Drug Administration revised some restrictions on donor eligibility to increase the donor pool and address concerns about blood shortages caused by cancellation of blood drives and physical distancing protocols, while still maintaining a very high degree of safety for transfusion recipients. (See 'Revised donor criteria to improve the blood supply during the pandemic' below.)

OVERVIEW

Role of the medical history — The medical history consists of basic information about risk factors for transfusion-transmitted infections and donor medical conditions. A combination of educational materials and specific questions are intended to help donors provide the most accurate and complete medical history.

Appropriate donor screening also avoids costs and burdens of collecting blood that is subsequently discarded due to infectious risk.

Donor history questions encompass the following domains:

Infectious organisms that are also screened by laboratory testing. (See "Blood donor screening: Laboratory testing", section on 'Infectious disease screening and surveillance'.)

Infectious organisms for which donated blood is not tested, such as malaria, other parasitic diseases, and prion disorders. (See 'Parasitic diseases' below and 'Prion disorders' below and 'Neurodegenerative disorders' below.)

Medications with teratogenic potential. (See 'Potential teratogens' below.)

Cancer. (See 'History of cancer' below.)

Assessment of heart disease, lung disease, or bleeding disorder in the prospective donor. (See 'Age cutoff and medical conditions' below.)

Information obtained from the donor history questionnaire determines whether the donor is eligible to give blood or whether the donor is deferred from donating on that day. Deferrals may either be temporary (for a defined time interval, usually 3 or 12 months), permanent, or indefinite; indefinite deferral does not have a time limit but is permanent unless donor eligibility criteria were to change in the future.

Development of donor history questions — All blood donors are required to answer medical history questions. These questions have evolved over time related to changes in infectious risks and to extend the blood supply during the COVID-19 pandemic. (See 'COVID-19 pandemic considerations' below.)

As examples:

1980s (HIV) – In the early 1980s, with the recognition of possible transfusion-transmitted human immunodeficiency virus (HIV) infection, additional donor questions concerning HIV risk factors were added to the medical history. In ensuing years, these questions evolved to include evaluation of high risk sexual activity, injection drug history, and history of sexually transmitted diseases. (See 'HIV' below.)

Donated blood is tested for anti-HIV-1 and anti-HIV-2 antibodies and HIV-1 ribonucleic acid (RNA), as discussed separately. (See "Blood donor screening: Laboratory testing", section on 'HIV-1 and HIV-2'.)

1990s (prion disorders) – Variant Creutzfeldt-Jakob disease (vCJD, a prion disorder) was first identified in the United Kingdom in 1996, and subsequent evidence suggested that transmission could occur via transfusion. Deferral criteria related to residence in Europe (or specific European countries) or other potential exposures were revised in 2020; some criteria remain in place and others were removed. (See 'Prion disorders' below.)

1990s (malaria) – In the United States, there is no laboratory testing of donated blood for malaria; the donor history is the only means of identifying malaria risk factors. Donor history questions regarding a history of malaria or risk factors for malaria (residence in or travel to malaria-endemic areas) were added in the mid-1990s. The time after returning from travel to a malaria-endemic area had been one year after departure from the area but was subsequently shortened to three months during the COVID-19 pandemic. (See 'Malaria' below and 'Revised donor criteria to improve the blood supply during the pandemic' below.)

2000s (babesiosis) – Questions regarding a history of babesiosis (infection with Babesia species) were added in the 2000s. (See 'Babesiosis' below.)

2010s (Zika virus) – Zika virus transmission from transfusion was reported during the 2015 to 2016 outbreak in the Americas, leading to addition of donor history questions related to Zika virus exposure. These questions were eliminated after laboratory testing was instituted; testing was removed after the outbreak waned. (See 'Zika virus' below.)

In the United States, medical history questions concerning specific risk factors for infectious diseases need to meet deferral criteria established by the US Food and Drug Administration (FDA). Variation is permitted in the exact wording of questions or in the format of interviewing blood donors. Each blood collection center's medical history standard operating procedure (SOP) must be approved by the FDA. In other countries, questions will be dictated by the appropriate regulatory authority [1,2].

In the United States, an interagency task force under the auspices of the Association for the Advancement of Blood & Biotherapies (AABB) developed and standardized a uniform set of donor questions and validated these through cognitively-based research protocols [1,3]. This initial Uniform Donor History Questionnaire (UDHQ) and its subsequent revisions have been approved by the FDA and, though not required, are used by most blood centers [4,5]. It can be administered orally or can be self-administered, with follow-up questioning by a health historian if the donor's responses raise questions about donor eligibility.

Many blood centers have implemented a computer-assisted self-interviewing (CASI) process that includes audio, pictorial (visual), and touch-screen components. A two-year evaluation at one blood center showed that identification of high-risk behaviors among prospective first-time donors significantly increased following the use of CASI when compared with results obtained from the previously administered oral questionnaire [6].

Historically it was required that the questionnaire be administered on the day of donation at the blood donation facility. Some blood centers have moved to offering the option of answering medical history questions through an online portal on the day of donation, prior to the donor arriving at the blood collection facility.

Because many questions in the medical history refer to events in the remote past, the FDA also approved an abbreviated donor history questionnaire (aDHQ) designed to identify recent changes in medical, behavior, and travel information that have occurred since a donor's previous donation [5]. The aDHQ eliminates questions about events or behaviors that, if a donor had previously answered "no" on the UDHQ, would not need to be asked in future interviews of that donor. To be eligible to receive the aDHQ, the donor has to donate at an acceptable frequency, and the blood collection agency needs to have a policy permitting use of this instrument.

Accuracy of donor responses — To maximize the accuracy of response, staff at the donation site should be encouraged to use appropriate nonjudgmental language, avoid culturally stigmatized terms, and refrain from behaviors that may be perceived as pressuring the donor. The value of donor history questions depends on the willingness of potential donors to reveal high-risk behaviors for infectious diseases and provide accurate information about their behaviors, general health, risk factors for infectious diseases, and medications.

The accuracy of donor responses to medical history questionnaires has been evaluated in the following studies:

General donor pool – Two retrospective studies from the Retrovirus Epidemiology Donor Study (REDS) published in 1993 and 1998 used anonymous post-donation surveys mailed to individuals who had donated blood within the previous four to eight weeks (together totaling approximately 100,000 donors) and compared results with information provided at the time of donation [7,8]. The survey asked questions related to demographic information, donation history, and history of HIV risk factors. Among respondents, approximately 2 to 3 percent reported behaviors that would have resulted in deferral had they been disclosed at the time of donation. A third post-donation survey study conducted by REDS in 2013 (at a time when men who have sex with men [MSM] sexual activity required a permanent deferral from donation) showed results consistent with these prior studies, in that 2.6 percent of male blood donors admitted to MSM sexual activity that they had not reported at the time of donation [9].

HIV and HCV seropositive donors – Various interview studies have documented that individuals seropositive for HIV or hepatitis viruses do not always disclose their high-risk behaviors at the time of donation, nor do they use the post-donation confidential call-back mechanism to disclose these behaviors [10-12]. Reasons for proceeding with the donation despite having high-risk behaviors that should have resulted in deferral included failure to read or fully comprehend the information in the donation material, pressure to donate, a desire to be tested for HIV, and the impression that laboratory screening would identify infected blood and lead to its removal. Some individuals did not consider their high-risk behaviors to be high risk because they were infrequent, were not recent, or had subsequently been modified.

These and other studies illustrate that a low level of increased risk continues to occur for certain transfusion-transmitted infections and that this risk is not identified by donor questioning. Continued efforts to improve the sensitivity of behavioral screening appear to be warranted [13]; laboratory testing remains critical. (See "Blood donor screening: Laboratory testing".)

COVID-19 PANDEMIC CONSIDERATIONS

Donation following COVID-19 vaccination — Individuals who have been vaccinated for COVID-19 can donate blood or blood components [14].

Those who have received a messenger RNA (mRNA) vaccine or other non-infectious vaccine (nonreplicating, inactivated) can donate immediately.

If a live attenuated COVID-19 vaccine were to be developed, it is likely that donor deferral would be 14 days. No live attenuated COVID-19 vaccines are authorized in the United States or are available for use anywhere in the world.

The Association for the Advancement of Blood & Biotherapies (AABB) has created a one-page fact sheet to explain the safety of transfusions from individuals who have been vaccinated [15].

Individuals who have recovered from COVID-19 may be eligible to donate convalescent plasma, depending on blood collection facility protocols and demand for COVID-19 convalescent plasma. (See "COVID-19: Convalescent plasma and hyperimmune globulin", section on 'Plasma donation'.)

Active or prior COVID-19 — There have not been cases of transfusion-transmitted infection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19. The US Food and Drug Administration (FDA) does not recommend testing donated blood for the virus, as respiratory viruses are not known to be transmitted by transfusion [16,17]. (See "Blood donor screening: Laboratory testing", section on 'Emerging infectious disease agents'.)

Having a history of COVID-19 or a positive test for SARS-CoV-2 (antibody, antigen, or nucleic acid) are not considered exclusions to donation as long as one of the following criteria are met [17]:

If symptomatic, the illness resolved more than 10 days prior to presenting to donate (reduced from 14 days in earlier guidance).

If asymptomatic, a positive test for the virus (antigen, nucleic acid) was more than 10 days prior to presenting to donate (reduced from 14 days in earlier guidance).

For individuals with possible COVID-19 without confirmatory testing, the FDA suggests that individuals refrain from donating blood for 10 days after either of the following:

Symptoms possibly caused by COVID-19 have resolved.

The last possible close-contact exposure to a person with an individual with SARS-CoV-2 infection has occurred.

Individuals who are currently ill with any symptoms such as fever or other active signs of infection are not eligible to donate. (See 'General symptoms of active infection' below.)

Donors are encouraged to contact the blood center if they develop symptoms compatible with COVID-19 or are diagnosed with COVID-19 in a defined period after donation (this ranges from 48 hours to 14 days depending on the blood center). Units from these individuals are removed from inventory.

Revised donor criteria to improve the blood supply during the pandemic — Critical blood shortages have occurred during the COVID-19 pandemic. Blood donation overall should be encouraged due to inventory shortages.

In the summer of 2020, many United States blood collection agencies responded to the difficulty in obtaining blood donations during the pandemic by establishing programs to test all blood donors for the presence of antibodies to SARS-CoV-2, both as an incentive to attract more blood donors as well as a method to identify antibody-positive donors who might be candidates to donate COVID-19 convalescent plasma (assuming an adequate antibody level or titer) [18]. This antibody testing was phased out in the spring and summer of 2021.

In April 2020, the FDA altered donor deferral criteria as a means of increasing the pool of available donors and maintaining the blood supply [19].

The revisions are related to three potential infectious risks:

HIV – Deferral for men who have sex with men (MSM) and individuals with most other HIV risk factors was shortened to three months [20]. Deferral for commercial sex workers and injection drug use was reduced from indefinite to three months [20]. (See 'HIV' below.)

Malaria – Deferral after return from travel to a malaria-endemic area was shortened from 12 months to three months [21]. Use of a pathogen inactivation technology (available for platelets and plasma but not for whole blood or red blood cell units) is an alternative to donor deferral for travelers. The three-year deferral for individuals who have resided in a malaria-endemic country or who have recovered from malaria remains in place. (See 'Malaria' below.)

Prion diseases – Several deferrals related to Creutzfeldt-Jakob disease (CJD) and variant CJD (vCJD) were altered [22]. (See 'Prion disorders' below.)

The FDA guidances provide for each United States licensed blood center to decide whether to implement the changes related to HIV and malaria [19]. They suggest that these policies will likely remain in place after the pandemic subsides, and they note that manufacturers of blood and blood components intended for use in other countries may elect to maintain longer deferrals [20].

SCREENING FOR INFECTIOUS RISKS

General symptoms of active infection — Bacterial infection is a potentially fatal complication of transfusion. The risk is greatest with platelet transfusion, since platelet units are stored at room temperature. (See "Transfusion-transmitted bacterial infection".)

To exclude donors who may be bacteremic, blood is not collected from persons who are febrile at the time of donation, who state that they do not feel well, or who are taking systemic antibiotics for an infection [23]. This policy may also serve to defer donors who are infected with other classes of infectious agents. (See 'Recent vaccination, antibiotic or antiviral medications, or biologic product' below.)

Deferral related to COVID-19 is discussed above. (See 'Active or prior COVID-19' above.)

There have been no reports of mpox (monkeypox) transmission from blood transfusion, and the FDA is not recommending that donors be asked specific questions about exposure to monkeypox virus [24].

These general requirements are also applied to candidates for autologous donation, since cases of transfusion-induced sepsis have occurred in recipients of autologous blood [25]. (See "Surgical blood conservation: Preoperative autologous blood donation".)

Recent vaccination, antibiotic or antiviral medications, or biologic product

Vaccination – Vaccination with live or attenuated viruses has the theoretical risk of transmitting infection. Transfusion-related transmission of yellow fever virus from persons with recent yellow fever vaccination has been reported from donors in whom a proper vaccine history was not obtained [26].

For some vaccines, there is no deferral period, as is the case for donors who are asymptomatic after receiving toxoids, synthetics, or killed vaccines, including COVID-19 vaccines. (See 'Donation following COVID-19 vaccination' above.)

For other vaccines, the recommended deferral period may be two or four weeks. For experimental, unlicensed vaccines (with the exception of COVID-19 vaccines), the deferral period may be as long as 12 months but may be shorter at the discretion of the facility's medical director. It should be noted that deferral intervals may vary between different blood collection organizations [27].

When the possibility of smallpox vaccination of segments of the United States population arose, specific questions were added to the donor history to address the recent receipt of a smallpox vaccination and skin contact with someone who was recently vaccinated. Positive responses required temporary deferrals (minimum of three weeks) to ensure that the potential donor was beyond the period of viremia [28]. Although smallpox vaccination campaigns are not ongoing, this question remains on the Uniform Donor History Questionnaire (UDHQ). (See 'Development of donor history questions' above.)

Antibiotics – Donors on a systemic antibiotic are deferred until they complete their full course of treatment. This requirement is designed to prevent transmission of bacteria and resultant sepsis in the recipient. Donors who are taking antibiotics for acne treatment are not deferred.

HIV PrEP or antiretroviral therapy for HIV – To prevent community spread of HIV, the use of HIV preexposure prophylaxis (PrEP) has dramatically expanded. It has been found that some individuals on a PrEP regimen were donating blood, despite the fact that the usual medical history questions should have been cause for deferral [29]. To prevent donation from persons taking PrEP, a specific question about PrEP use was added to the donor screening process. Individuals on a regimen of PrEP or postexposure prophylaxis (PEP) with tenofovir (Truvada), emtricitabine (Descovy), dolutegravir (Tivicay), or raltegravir (Isentress) are deferred until they have been off of their regimen for three months [30]. The rationale for this deferral is that these medications may suppress HIV to levels that are below the limit of detection of HIV laboratory tests but that are still high enough to result in transfusion transmission [29].

There is an indefinite deferral for individuals who are currently or who have ever in the past received antiretroviral therapy for HIV [30].

Biologic products – Donors are permanently deferred if they have received a cadaveric dura mater transplant; this is due to risk of iatrogenic Creutzfeldt-Jakob disease (iCJD). Donors are indefinitely deferred if they received a xenotransplant (a transplant of a tissue or organ from another animal species); exceptions are porcine heart valves or porcine insulin.

Viruses — Risks of transfusion-transmitted viral infections are summarized in the table (table 1). These risks and questions to elicit them are discussed in the following sections. SARS-CoV-2 (the virus that causes COVID-19) is not considered to be a bloodborne virus, as discussed above. (See 'COVID-19 pandemic considerations' above.)

HIV

Risk of HIV from transfusion — The risk of HIV from blood transfusion is estimated to be approximately 1 in 1.5 to 2 million units when blood is tested using nucleic acid testing (NAT) for viral RNA (table 1); in the United States, minipool NAT (MP-NAT) is used [31-33]. This risk has been significantly reduced since the early years of the HIV epidemic in the 1980s [34].

Risk has been decreased by the following:

Reduced population prevalence – The rate of HIV seropositivity has declined in the blood donor population (individuals who have passed the screening and donate blood), from approximately 3.5 per 10,000 donations in the late 1980s to approximately 0.3 per 10,000 donations in the 2010s [35,36]. HIV continues to have a disproportionate impact on certain groups of people, as discussed separately. (See "Global epidemiology of HIV infection", section on 'Worldwide statistics'.)

Donor deferral – Donor medical history screening educates donors about risk factors and facilitates deferral, including self-deferral, at various times before and after donation. (See 'Deferral criteria related to HIV' below.)

Laboratory testing – All donations are tested for HIV-1 and HIV-2 using a combination of antibody testing for HIV-1 and HIV-2 and NAT for HIV-1 RNA. In the United States, MP-NAT is done by pooling of 6 to 16 specimens; in some other countries, individual donations are tested. (See "Blood donor screening: Laboratory testing", section on 'HIV-1 and HIV-2'.)

Historically (prior to 1985, when HIV testing was first instituted), transfusion of a product from an individual with HIV had a high probability (90 percent) of transmitting HIV. Rates of transfusion-transmitted HIV were equivalent from red blood cells (RBCs) stored for <21 days, platelets, or plasma.

Since the institution of HIV-NAT and antibody testing, the risk of transfusion-transmitted HIV in the United States is approximately 1 in 1.6 million to 1 in 2.3 million (table 1) [37,38]. Remaining reasons for HIV transmission include:

Window period transmission – Despite medical history and laboratory screening processes, there is still an exceedingly rare possibility for HIV transmission if blood is donated during the window period (the period when the donor is infectious but laboratory testing is negative) [11,34,35,39]. The window period is approximately 11 days when blood is tested by MP-NAT and approximately 8 days when tested by ID-NAT [40]. (See "Blood donor screening: Laboratory testing", section on 'HIV-1 and HIV-2'.)

Transfusion-transmission risk is proportional to the volume of plasma in the transfused blood component; as an example, to transmit infection, a RBC component will require a 10-fold greater concentration of virions in the donor's blood than will a plasma component. This is based on the relative volumes of plasma in different blood components (20 mL of plasma in a typical RBC unit versus 200 mL of plasma in an FFP unit). Infection may occur with as few as two to three HIV virions in the entire plasma volume of the transfused blood component [34,41,42].

Other reasons for transmission – Other theoretical reasons for transfusion-transmitted HIV have been proposed, including infection with an HIV variant that escapes detection by available laboratory assays or an error in testing or labelling (clerical error) [43].

HIV genetic variation – In principle, available laboratory testing may fail to identify genetic variants of HIV that evolve over time, although this has never been documented. HIV testing includes serologic (antibody) assays for HIV-1, the overwhelmingly predominant strain responsible for transfusion-transmitted HIV prior to laboratory testing, and HIV-2, which was implicated in fewer than 50 cases of transfusion-transmitted HIV, occurring primarily in Portugal [44].

Antibodies to HIV-1 and HIV-2 show extensive crossreactivity; as a result, up to 90 percent of sera from HIV-2-infected persons test positive on US Food and Drug Administration (FDA)-licensed HIV-1-based screening assays [45]. There have been no cases of HIV-2 transmission after HIV-1 and HIV-2 serologic testing were instituted in Europe and North America.

Clerical error – The use of two independent methods of testing (HIV-1 and HIV-2 antibody and HIV-1 RNA) on each unit greatly decreases the risk of infection caused by clerical error. (See "Blood donor screening: Laboratory testing", section on 'HIV-1 and HIV-2'.)

The risk of HIV transmission from other products is zero or negligible.

IVIG, SCIG, and albumin – HIV is inactivated by the purification process used to produce plasma derivatives such as albumin and immune globulin products, including intravenous immune globulin (IVIG) and subcutaneous immune globulin (SCIG). There has never been a documented case of HIV transmission from albumin or immune globulin preparations. (See "Plasma derivatives and recombinant DNA-produced coagulation factors".)

Pathogen-inactivated blood products – Pathogen inactivation procedures that damage nucleic acids are able destroy HIV and other viruses. (See "Pathogen inactivation of blood products", section on 'Plasma derivatives including clotting factors and fibrinogen'.)

Plasma-derived clotting factors – Prior to 1984, people with hemophilia who received plasma-derived clotting factor concentrates developed HIV from exposure to concentrates from individuals with HIV [46]. With improved viral inactivation procedures (pasteurization, chromatography, solvent/detergent treatment) for plasma derivatives in the mid-1980s, and the addition of HIV antibody and RNA testing, there have been no documented HIV transmissions from clotting factor concentrates. In vitro data demonstrate that these procedures kill HIV in a logarithmic fashion [47]. Testing of donors is still required to exclude plasma with extremely high viral titers that might otherwise escape these inactivation procedures.

Educational information about HIV, history screening, and documentation — Recommendations for screening prospective donors were issued by the FDA in 1992 and remained largely unchanged until 2015 [48]. The following educational information is provided:

HIV risk factors – Donors are provided with educational materials prior to each donation that explain the risk of HIV transmission by blood transfusion, discuss behaviors associated with HIV risk, and describe symptoms that are potentially compatible with acute HIV infection (fever, enlarged lymph nodes, sore throat, rash), as specified in the 2015 guidance [49]. The purpose is to prompt the donor to self-defer if they have HIV risk factors. The information can be in an oral, written, or multimedia format. Donors are asked health history questions about behaviors associated with increased risk for HIV infection [49].

Window period – Donors are informed that it is possible to transmit HIV during the window period when a donor may be infectious and capable of transmitting HIV despite having a negative HIV test when first infected with HIV [48].

Laboratory testing – Donors are informed that all units of donated blood will be tested for HIV; if the test is positive, they will be notified of the result [49]. They are informed that they will be permanently deferred if they test positive for HIV.

Donors are told that they should not use the donation facility to obtain HIV testing. Donors should be provided information on how to obtain an HIV test at a site other than the donor center.

Self deferral – Donors are told to self-defer if they have risk factors for HIV infection; risk factors are included in the educational materials and summarized below. (See 'Deferral criteria related to HIV' below.)

Acknowledgment – Donors must sign an acknowledgment agreeing not to donate if the donation could result in a potential risk to recipients (including risk of HIV infection) as described in the donor educational material.

Deferral criteria related to HIV — Donors who have ever been diagnosed with or treated for HIV are indefinitely deferred.

HIV risk factors that are solicited as part of the donor medical history and that result in a temporary deferral (three months) include the following:

Men who have sex with men (MSM) or females who have had sexual contact with a MSM

Commercial sex work (engaging in sex in exchange for money or drugs) or having sex with a commercial sex worker

Having sex with a person who has ever had HIV or tested positive for HIV

Being exposed to blood through transfusion, needlestick injury or blood splash to mucous membrane or non-intact skin

Use of intravenous recreational drugs

Tattoos or body piercing (unless done in appropriately certified venues using sterile equipment)

Being diagnosed with or treated for a sexually transmitted disease (syphilis or gonorrhea)

Taking PrEP for HIV (regardless of whether there are HIV risk factors or an HIV exposure) (see 'Recent vaccination, antibiotic or antiviral medications, or biologic product' above)

Prior to 2016, most of the above risk factors resulted in an indefinite deferral. From 2016 to 2020, deferral for MSM was shortened to 12 months; data from a large study in the United States demonstrated that this policy change did not increase the incidence of HIV infection in the donor population [50]. In 2020, the MSM deferral was shortened to three months [51,52]. (See 'COVID-19 pandemic considerations' above.)

The rationale for this change is that HIV risk behaviors that ended at a specific point in time should only defer a prospective donor until laboratory testing can definitively prove that the individual is free of HIV infection. Scientific data indicate that this should be <3 months when combined HIV antibody testing and NAT are used. Countries that have adopted such shortened deferral periods (Canada, Australia) have not documented any increase in transfusion transmission of HIV.

In 2021, the United Kingdom ended its deferral for MSM activity and instead instituted questioning of all donors about new sexual partners and sexual practices such as anal sex; anal sex with a new partner (male or female) will result in a three-month deferral [53].

Hepatitis B and C viruses — United States federal guidelines for preventing transfusion-transmitted hepatitis were established decades ago in the Code of Federal Regulations and subsequently revised [54-57].

As of 2016, there is no longer an FDA or Association for the Advancement of Blood & Biotherapies (AABB) requirement to ask the donor about a history of viral hepatitis [57]. However, if a potential donor volunteers a history of a prior diagnosis of hepatitis B virus (HBV) infection, hepatitis C virus (HCV) infection (even if their HCV infection has been treated and cured), or viral hepatitis of unknown type, the donor is permanently deferred.

Additional deferral policies are as follows:

Persons currently or previously confirmed positive for hepatitis B surface antigen (HBsAg) are permanently deferred. Persons who volunteer a history of prior diagnosis of HBV infection are also permanently deferred.

Donors who have received hepatitis B immune globulin (HBIG) are deferred for one year.

Persons with a history of close contact with someone who has viral hepatitis are deferred for 12 months following their last potential exposure.

The definition of close contact with a person with viral hepatitis clearly includes sexual contact. Other aspects of close contact are more problematic to define. The definition used by the UDHQ is living in the same dwelling; this implies the sharing of household, kitchen, or toilet facilities. For HBV, this definition appears reasonable, since HBV can rarely be transmitted from an acutely infected patient to a household contact, probably through nonsexual contact with body fluids [58]. Data do not support similar transmission for HCV, and deferral is not required for sexual or other close contact with an asymptomatic HCV carrier [59]. The 12-month deferral policy applies to close contact with persons who have HBV, symptomatic HCV, or viral hepatitis of unknown origin.

Persons who have received a blood transfusion are deferred for three months (previously was 12 months).

Questions about receiving a tattoo or body piercing within the last three months (previously 12 months) are asked, due to concerns about hepatitis or other infectious disease transmission [60]. However, affirmative answers do not necessarily result in deferral.

Most blood centers will accept donors with body piercing(s), provided the procedure was performed with sterile, single-use equipment.

Donors with tattoos or permanent makeup are deferred for three months (previously 12 months) after the exposure, unless the application was done using sterile needles and nonreusable ink in a state that has a regulatory body that licenses tattoo parlors. If these conditions are met, and at the discretion of the local blood collection agency, donor deferral is not necessary.

In Europe, an additional process for risk mitigation of viral hepatitis is a temporary (four to six month) deferral after an endoscopic procedure. A 2018 meta-analysis of 29 observational studies concluded that there is an increased risk of HBV or HCV infection in patients who have undergone endoscopic procedures [61]. However, the authors acknowledged that the quality of the data was very low and that the data were confounded, in that almost all of the cited studies that established increased risk did not distinguish whether the HBV or HCV infections occurred prior to or following the procedures.

Subsequently, a study of donors deferred for endoscopic procedures in Australia reviewed pre- and post-endoscopy laboratory screening data for HIV, HBV, and HCV and concluded that the risk from accepting such donors was extremely small; this led the Australian blood regulator to discontinue this deferral criteria [62].

West Nile virus — West Nile virus (WNV) is a mosquito-borne flavivirus that can cause encephalitis. Most transmission is via mosquitoes. (See "Epidemiology and pathogenesis of West Nile virus infection" and "Clinical manifestations and diagnosis of West Nile virus infection".)

Since 2003, blood collection facilities in the United States have performed NAT for WNV during routine laboratory screening. (See "Blood donor screening: Laboratory testing", section on 'West Nile virus'.)

Based on data from transfusion-transmitted WNV cases occurring in 2002 prior to the use of laboratory testing, it was hypothesized that a question asking about the occurrence of fever and headache in the week prior to donation might provide additional protection against WNV transmission. In 2003, this question was added to the donor history [63]. A subsequent evaluation of two years of data from donors with laboratory-proven WNV infection failed to find a correlation between these predonation symptoms and WNV infection, and it was concluded that this question leads to unnecessary deferral of eligible donors. Consequently, this history question was eliminated from the donor questionnaire [64]. As with other acute viral syndromes, a general donor history question about whether the donor feels well may elicit the presence of nonspecific systemic complaints leading to donor deferral. (See 'General symptoms of active infection' above.)

Zika virus — Zika virus is a mosquito-borne flavivirus (the same virus family that includes WNV and dengue virus). Infected persons are most often (80 percent) asymptomatic; symptomatic cases usually have a mild febrile illness that may be associated with muscle or joint pain, headache, retro-orbital pain, conjunctivitis, and skin rash [65]. More serious clinical outcomes can include Guillain-Barré syndrome and congenital microcephaly and fetal losses in women infected during pregnancy [66,67]. (See "Zika virus infection: An overview" and "Arthropod-borne encephalitides".)

Several cases of Zika virus transmission from transfusion were reported during the 2015 to 2016 outbreak in the Americas [68,69]. These cases were detected after a donor reported post-donation symptoms compatible with an arboviral illness that was subsequently diagnosed as Zika virus infection. The recipients with transfusion-transmitted-Zika did not develop symptoms attributable to Zika virus infection.

At that time, several United States and international agencies issued guidance to reduce the risk of transmission from symptomatic and asymptomatic donors based on the donor medical and travel history.

In the United States, these questions were removed when blood donor testing was implemented in 2016, and the requirement for laboratory testing was removed in 2021, based on the evolving epidemiology of Zika virus and the absence of active infections in the United States [70]. (See "Blood donor screening: Laboratory testing", section on 'Zika virus'.)

The following describes the historical recommendations:

US FDA – In February 2016, the FDA issued guidance to reduce the risk of Zika virus transmission from blood transfusions that included a four-week deferral of at-risk donors, including persons who had traveled to an area with active Zika transmission during the prior four weeks, those with symptoms of Zika virus infection, and those who had sexual contact with a male who traveled to or resided in an area with active Zika virus transmission during the prior three months [71]. If this information was obtained after the blood unit had been collected, the blood center was instructed to quarantine and destroy the in-date blood components still in inventory. The requirement for donor history questioning related to Zika virus was discontinued when laboratory testing was instituted.

AABB – The AABB recommended that there be post-donation notification of the donation facility by donors who develop symptoms common to Zika, dengue, or chikungunya virus in the 14 days following their donation [72].

If a donor states that they were diagnosed with confirmed Zika virus infection, blood centers must inform hospitals of products collected and distributed within the previous 120 days and any in-date products must be removed from inventory. Recipients of such products should be assessed for possible Zika virus infection [72].

Parasitic diseases

Malaria — Malaria is a mosquito-borne protozoal RBC parasite, of which there are several species. (See "Malaria: Clinical manifestations and diagnosis in nonpregnant adults and children" and "Non-falciparum malaria: P. vivax, P. ovale, and P. malariae" and "Non-falciparum malaria: Plasmodium knowlesi".)

Transfusion-transmitted malaria (TTM) is common in some parts of the world but is rare in the United States. Between 2000 and 2017, there were 11 reported cases of TTM in the United States for an estimated rate of <0.1 per million RBC units transfused [73,74].

Due to differing epidemiology (eg, immigration from malarial endemic areas), policies to reduce transfusion-transmission risk vary internationally [75]. In the United States, donated blood is not tested for malaria (see "Blood donor screening: Laboratory testing"), and policies for preventing TTM rely on donor questioning during the health history interview.

This includes questions about:

Symptoms – General symptoms of infection such as fever. (See 'General symptoms of active infection' above.)

Diagnosis – Donors with a history of malaria are deferred for three years after becoming asymptomatic, based on 2013 FDA criteria [76].

Exposure – Travel or residence in malaria-endemic regions of the world.

Travel – FDA guidance states that individuals who reside in a country where malaria is not endemic and who travel to a malaria-endemic area for 24 hours or more are deferred for three months from the date of last departure from the endemic area (provided they have not had malarial symptoms). Prior to April of 2020, the deferral period was one year. The reduction to three months was based on a Centers for Disease Control and Prevention analysis of surveillance reports of malaria cases imported to the United States [21]. This applies even if travel was limited to travel through a malaria endemic area enroute to a malaria-free area, provided the time spent in the endemic area extended beyond 24 hours; common examples include passage through a malaria-endemic area to visit a tourist resort in a malaria-free area, passage through a malaria-endemic area to board a cruise ship, or on-shore excursions into a malaria-endemic area when traveling on a ship.

Not all malaria-endemic areas pose equal risks. In one study, travel to Africa was estimated to present a risk for malaria infection >1000 times that of travel to endemic parts of Mexico [74]. Shortening the deferral period for visitors to Mexico from 12 to three months was estimated to increase the risk of collecting a contaminated unit by one unit every 57 years, at an annual gain of more than 56,000 donations. Given these data and the changing epidemiology of malaria in Mexico, donors who visit specific areas of Mexico that formerly required donor deferral (eg, the states of Jalisco and Quintana Roo, the latter containing the resort area of Cancun) are no longer required to be deferred [76].

For individuals who reside in a country where malaria is not endemic and travel to an area where malaria is endemic, pathogen inactivation technologies (available for platelets and plasma) can be used as an alternative to a three-month donor deferral. (See "Pathogen inactivation of blood products", section on 'Malaria and other parasites'.)

Residence – Residence refers to living in a malaria-endemic country for >5 years, based on FDA criteria established in 2013 [76]. These individuals are deferred for three years after their departure from the endemic country, assuming they do not travel to any malaria-endemic country during that three-year period. This criterion is based upon the premise that such individuals may have partial tolerance to malarial parasites, thereby resulting in the delay of malarial symptoms.

These policies represent a compromise between prevention of transmission and acceptable levels of donor deferral, in that it is well known that a Plasmodium malariae chronic carrier state may persist for decades, resulting in transfusion transmission many years after the resolution of symptoms. (See "Non-falciparum malaria: P. vivax, P. ovale, and P. malariae", section on 'P. malariae'.)

Chagas disease — Chagas disease (American trypanosomiasis) is caused by infection with the protozoan parasite Trypanosoma cruzi. (See "Chagas disease: Epidemiology, screening, and prevention".)

Chagas disease has rarely been reported to be transmitted by blood transfusion in North America, with fewer than 10 reported cases, almost exclusively due to platelet transfusions.

Laboratory testing of donated blood for T. cruzi is performed on a selective basis. Since 2010, many blood collection centers in the United States have adopted an approach in which donors are screened with an antibody test for prior exposure to T. cruzi on their initial donation, but the testing is not repeated on subsequent donations if the initial testing was negative. (See "Blood donor screening: Laboratory testing", section on 'Chagas disease'.)

Medical history questions concerning previous diagnosis of Chagas disease, country of birth, and travel to countries where Chagas disease is endemic, are not included as part of the screening process in the United States. [77].

Babesiosis — Babesiosis is a tick-borne parasitic infection of RBCs in which clinical symptoms may range from asymptomatic to life-threatening. Different Babesia species are found in different geographic regions (eg, B. microti in the Northeast and Midwest regions of the United States). (See "Babesiosis: Microbiology, epidemiology, and pathogenesis" and "Babesiosis: Clinical manifestations and diagnosis".)

More than 150 cases of transfusion-associated babesiosis have been reported in the United States [78-80].

Laboratory testing for Babesia species is performed by NAT on a selective basis on donations from blood collectors in states with a higher prevalence of babesiosis. (See "Blood donor screening: Laboratory testing", section on 'Babesia microti'.)

Donor questioning is limited to asking donors whether they have ever had babesiosis. If so, the donor must be deferred for two years but can then be eligible for reinstatement if they go through a specific laboratory testing protocol. Alternatively, the donor may be deferred indefinitely. Questions about tick bite history are not sensitive or specific for babesiosis [81,82].

Pathogen inactivation technologies can be used as an alternative to donor deferral. (See "Pathogen inactivation of blood products", section on 'Malaria and other parasites'.)

Prion disorders

Creutzfeldt-Jakob disease — Creutzfeldt-Jakob disease (CJD) is a rare, fatal, degenerative neurologic disorder caused by a prion. Prions are abnormal proteins that cause central nervous system neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs). CJD has a long asymptomatic latent period. Prions cannot be inactivated by conventional sterilization techniques. (See "Diseases of the central nervous system caused by prions", section on 'Pathogenesis of prion diseases'.)

Several forms of CJD are recognized, including sporadic (sCJD), iatrogenic (iCJD), and genetic (gCJD, also called genetic CJD [gCJD]). Variant CJD (vCJD) is different from these other forms of CJD in several ways, including that it has been shown to be transmitted by transfusion.

vCJD – (See 'Variant CJD risk and deferral criteria' below.)

iCJD – Human-to-human transmission of iCJD has occurred with transplantation of dura mater, by corneal transplantation, injection of pituitary derived human growth hormone, and reuse of electroencephalography (EEG) electrodes, but not by blood transfusion. (See "Creutzfeldt-Jakob disease", section on 'Iatrogenic CJD'.)

Epidemiologic studies (including a review of mortality data in heavily transfused recipients, neuropathological studies of deceased patients with hemophilia, and lookback studies assessing the health outcome of recipients who received blood components from donors who subsequently developed iCJD or other neurodegenerative disorders) have failed to establish a link between transfusion and transmission of types of CJD other than vCJD [83-86].

Despite a consensus that CJD is not transmitted by transfusion, it remains a theoretical risk due to the long incubation period [87,88]. Donors are deferred if they have a suspected diagnosis of CJD or if they have received a cadaveric dura mater transplant.

gCJD – Donors are deferred if they volunteer the information that a blood relative has been diagnosed with gCJD.

Variant CJD risk and deferral criteria — Variant Creutzfeldt-Jakob disease (vCJD) is a fatal, degenerative neurologic disease discovered in the United Kingdom in 1996 [89]. The prion that causes vCJD also causes bovine spongiform encephalopathy (BSE, also called "mad cow disease") [90]. Soon after the discovery of vCJD, the risk of transfusion transmission of this agent in humans was proposed. Over the next several years, four cases of probable transfusion transmission of the vCJD agent were reported in the United Kingdom. Three were associated with clinical disease, which developed from approximately 5 to 10 years after transfusion [91-96]. (See "Variant Creutzfeldt-Jakob disease".)

The following deferral criteria for vCJD risk were affirmed in a 2020 FDA guidance document [22]. Permanent deferral applies to individuals ever diagnosed with vCJD. Indefinite deferral applies to individuals who:

Spent ≥3 cumulative months in the United Kingdom from 1980 to 1996.

Spent ≥5 cumulative years in France or Ireland from 1980 to 2001.

Received a blood transfusion in the United Kingdom, France, or Ireland from 1980 or later.

The 2020 FDA guidance eliminated deferral for individuals based on the following [22]:

Spent ≥5 cumulative years in countries in Europe (other than those specified above) from 1980 or later.

Served as military personnel, civilian military employees, or their dependents, living on military bases in Europe from 1980 thru 1996.

Injected bovine insulin sourced from the United Kingdom or other countries with BSE.

SCREENING FOR NON-INFECTIOUS RISKS

History of cancer — Transmission of cancer from a donor to a recipient has not been reported. However, donors are questioned about active cancer, since many transfusion recipients are immunosuppressed and there is a theoretical risk that malignant cells could engraft in the recipient.

Available data regarding transfusion of components from donors subsequently diagnosed with malignancy includes:

A retrospective series of over 350,000 transfusion recipients in Denmark and Sweden from the ScanDat database identified 12,012 (3 precent) who were exposed to blood products from donors who subsequently developed cancer and were considered to have subclinical cancer at the time of the donation [97]. The adjusted risk of cancer in the recipients from these donors was not increased (adjusted relative risk [RR] 1.00; 95% CI 0.94-1.07). A second study using the ScanDat database showed no transmission of chronic lymphocytic leukemia (CLL) to recipients of blood from donors who later developed CLL [98].

A series of 105 individuals who were exposed to blood products from donors with hematologic malignancies (leukemia or lymphoma) were followed for >7 years, and none developed a hematologic malignancy [99].

A case report described transfusion from a donor who was subsequently diagnosed with chronic myeloid leukemia (CML) [100]. The DNA sequence from the CML clone was detectable in the recipient's blood for 75 days. The recipient died eight months after the transfusion from an unrelated cause, so the significance of this finding remains unknown.

The US Food and Drug Administration (FDA) makes no recommendations about prospective donors with cancer and does not require that blood centers ask questions concerning a history of cancer. Standards from the Association for the Advancement of Blood & Biotherapies (AABB) state that the prospective donor must be in good health and free of major organ diseases such as cancer; furthermore, a question regarding a history of cancer is included on the Uniform Donor History Questionnaire (UDHQ). (See 'Development of donor history questions' above.)

The blood center medical director determines the center's deferral policy. Most blood centers use the following criteria based on the type of malignancy:

Solid organ cancer – Deferral until the donor has been symptom-free and considered to be clinically cured for a defined time period (typically one to five years, depending on the blood center).

Hematologic cancer – Permanent deferral.

Localized cancer that cannot spread hematogenously – No deferral once the cancer has been excised. Examples include basal cell cancer of skin and cervical carcinoma in situ.

Neurodegenerative disorders — The risk of transfer of a neurodegenerative disorder such as Alzheimer disease from blood products does not appear to be increased. In a retrospective study involving over 1.4 million transfusion recipients, 2.9 percent received a transfusion from a donor who was diagnosed with dementia of any kind, Alzheimer disease, or Parkinson disease [86]. There was no increased risk of recipients developing dementia (hazard ratio [HR] 1.04; 95% CI 0.99 to 1.09), Alzheimer disease (HR 0.99; 95% CI 0.85-1.15), or Parkinson disease (HR 0.94; 95% CI 0.78 to 1.14).

Eligibility for donors with these conditions does not involve a concern related to disease transmission. Rather, if the donor volunteers during the screening process that they were diagnosed with Alzheimer disease or Parkinson disease, their eligibility is based on an assessment by the blood donation facility staff of whether the donor has the cognitive ability to provide reliable answers to the screening questions and whether the donor is physically able to tolerate the phlebotomy.

Risks of prion-related neurodegenerative disorders are exceedingly low, but at-risk donors are deferred. (See 'Prion disorders' above.)

Medications taken by the donor — Most medications taken by donors pose no known risks to recipients. In most cases, only small quantities of drugs are present in a unit of blood and the drugs will undergo significant dilution in the recipient's plasma volume. However, donors taking certain medications are deferred, either for a defined period of time after stopping the medication or indefinitely.

Medications that indicate possible infectious risk are discussed above. (See 'Recent vaccination, antibiotic or antiviral medications, or biologic product' above.)

The possibility of allergic reactions in a recipient related to substances ingested by the donor is discussed separately. (See "Immunologic transfusion reactions", section on 'Allergic reactions'.)

Potential teratogens — Some drugs may pose a risk to transfusion recipients who may become pregnant, due to their demonstrated teratogenic potential at low concentrations. Information from the AABB specifies the following deferral intervals following discontinuation of the medication [30]:

Acitretin (Soriatane), used for psoriasis – 36 months

Dutasteride (Avodart, Jalyn), used for benign prostatic hypertrophy – 6 months

Etretinate (Tegison), used for psoriasis – indefinite

Finasteride (Propecia, Proscar), used for benign prostatic hypertrophy and hair regeneration – 1 month

Isotretinoin (Accutane, Amnesteem, Absorica, Claravis, Myorisan, Sotret, Zenatane), used for acne – 1 month

Leflunomide (Arava), used for rheumatoid arthritis – 24 months

Mycophenolate mofetil (CellCept), used for immunosuppression – 6 weeks

Sonidegib (Odomzo), used for basal cell carcinoma - 24 months

Teriflunomide (Aubagio), used for multiple sclerosis – 24 months

Thalidomide (Thalomid), used for multiple myeloma – 1 month

Upadacitinib (Rinvoq), used for rheumatoid arthritis – 1 month

Vismodegib (Erivedge), used for basal cell carcinoma – 24 months

The donor history is the only means of identifying these exposures; there is no routine testing for the presence of these medications.

Antiplatelet drugs and anticoagulants — Information from the AABB specifies deferring donors for platelet apheresis donation if any of the following antiplatelet medications were taken within the following timeframes [30]:

Aspirin, aspirin-containing drugs, or piroxicam – Previous 2 days

Prasugrel – Previous 3 days

Ticagrelor – Previous 7 days

Clopidogrel or ticlopidine (not available in the United States) – Previous 14 days

Vorapaxar – Previous month

This donation restriction is specific to platelet apheresis donors and does not apply to whole blood donors, unless platelets made from that unit of whole blood will be the sole source of platelets for a given patient. This would apply only to whole blood derived platelet transfusions designated for neonatal and young pediatric recipients.

The donor history is the only means of identifying these exposures; there is no routine quality control testing of platelet function or clotting tests for platelet apheresis products. This is due in part to the inability of in vitro platelet function testing to accurately predict in vivo platelet function.

The deferral period for individuals taking an anticoagulant is based on two factors: the concern that the donor may have excessive bleeding at the venipuncture site and the potential effect of the anticoagulant on the clotting properties of the donated plasma. Donors taking anticoagulants are uniformly deferred from platelet apheresis donation. However, some blood centers may elect to collect whole blood from such donors if they judge the bleeding risk at the phlebotomy site to be minimal and if they have a method to be sure that the plasma derived from such collections (which would have impaired coagulation properties) is not used for transfusion. The timeframes are as follows for the various different anticoagulant medications [30]:

Direct oral anticoagulants (DOACs; apixaban, dabigatran, edoxaban, rivaroxaban), fondaparinux, and the low molecular weight (LMW) heparins dalteparin and enoxaparin – Previous two days.

Warfarin and LMW heparins other than dalteparin and enoxaparin – Previous seven days.

AGE CUTOFF AND MEDICAL CONDITIONS — The minimal age for donation is legally established by individual states in the United States and is either 16 or 17 years; donors who are legally minors need written consent of a parent or guardian. Most blood centers do not have an upper age limit for donation; this policy is based on studies documenting that individuals over the age of 65 who met all other donation criteria had no greater frequency of severe or life-threatening reactions and had lower rates of post-transfusion reactions than younger donors [101]. (See "Blood donor screening: Overview of recipient and donor protections", section on 'Age and weight cutoffs'.)

Medical conditions that could result in risks to the donor and donor protections are discussed separately (See "Blood donor screening: Overview of recipient and donor protections", section on 'Protection of the donor'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Transfusion and patient blood management".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Basics topics (see "Patient education: Blood donation (giving blood) (The Basics)")

Beyond the Basics topics (see "Patient education: Blood donation and transfusion (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

Importance of the medical history interview – The major procedure for screening donors at the donation site is the medical history interview, which contains questions to reduce the risks of transfusion-transmitted infection and adverse reactions to donation. These questions are continually reviewed and updated as new risks arise. (See 'Overview' above.)

COVID-19 – Individuals who have had coronavirus disease 2019 (COVID-19), asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and/or vaccination for COVID-19 can donate, as long as 10 days have passed from the resolution of symptoms or a positive test. Deferral is not required after receipt of available mRNA or adenoviral vectored vaccines. During the pandemic, the US Food and Drug Administration (FDA) has altered other deferral criteria related to certain infectious risks (HIV, malaria, prion diseases) to increase the blood donor pool and blood supply while maintaining a very high degree of safety for transfusion recipients. (See 'COVID-19 pandemic considerations' above.)

Specific questions – The following components of the blood donor medical history are used to protect the recipient from transfusion-transmitted infectious diseases and other risks:

Acute infections – Blood is not collected from persons who are febrile at the time of donation, who state that they do not feel well, or who are taking systemic antibiotics. (See 'General symptoms of active infection' above and 'Recent vaccination, antibiotic or antiviral medications, or biologic product' above.)

HIV – Donors are asked about sexual activities, injection drug use, prior HIV testing, and history of syphilis or gonorrhea. (See 'HIV' above.)

Other viral and parasitic diseases – Donors are asked questions related to risk for hepatitis and other viral infections, parasitic diseases (malaria, babesiosis), and prion disorders such as variant Creutzfeldt-Jakob disease (vCJD). Travel-related questions are relevant to potential exposure to malaria or vCJD. (See 'Hepatitis B and C viruses' above and 'Parasitic diseases' above and 'Prion disorders' above.)

Medical conditions – In most blood centers, a donor with a history of a solid organ tumor will be eligible to donate only if they have been symptom-free and considered to be clinically cured for a defined time period. Donors with a history of hematologic malignancy are permanently deferred. (See 'History of cancer' above.)

For their own protection, individuals are deferred from donating if they have certain types of cardiac or pulmonary disease, have undergone recent surgery, have neurodegenerative disorders that interfere with their ability to tolerate the donation procedure, or are pregnant. Individuals with seizure disorders are able to donate provided they have been seizure-free for a specified period of time. The minimal age for donation is typically 16 to 17 years, depending on state laws. Most blood centers do not impose an upper age limit for donor eligibility. (See 'Age cutoff and medical conditions' above and "Blood donor screening: Overview of recipient and donor protections", section on 'Protection of the donor'.)

Medications – Some drugs may pose a risk due to their demonstrated teratogenic potential at low plasma concentrations or effects on platelet function or coagulation. (See 'Medications taken by the donor' above.)

-Deferral periods for medications with teratogenic potential are listed above. (See 'Potential teratogens' above.)

-Donors who have received hepatitis B immune globulin (HBIG) are deferred for one year, as are donors who received an experimental or an unlicensed vaccine, unless otherwise indicated by the blood collection facility medical director. (See 'Prion disorders' above and 'Recent vaccination, antibiotic or antiviral medications, or biologic product' above.)

-Apheresis platelet donors are deferred if they have recently taken an antiplatelet agent or anticoagulant. Specific deferral periods are listed above. (See 'Antiplatelet drugs and anticoagulants' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff gratefully acknowledges extensive contributions of Arthur J Silvergleid, MD to earlier versions of this and many other topic reviews.

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Topic 7950 Version 58.0

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