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Patient education: What you should know about vaccines (The Basics)

Patient education: What you should know about vaccines (The Basics)

What are vaccines? — Vaccines can prevent certain serious or deadly infections. They are a way of teaching your body how to fight the germs that cause infections. Thanks to vaccines, many fewer people get seriously ill or die from infections than in the past.

Vaccines usually come in shots, but some come in nose sprays or medicines you swallow. When a person gets a vaccine, this is called "vaccination" or "immunization."

How do vaccines work? — To understand how vaccines work, it helps to understand what happens when you get an infection. Infections are caused by germs, such as bacteria or viruses. When a germ gets into your body, it multiplies (makes copies of itself) and attacks your cells. This is what makes you sick. Your "immune system," or infection-fighting system, recognizes that the germ should not be there. In response, it starts to make proteins called "antibodies" to fight the germ.

There are different types of vaccines. They all work by causing your body to make antibodies, like it would if you had an infection. This prepares your immune system to fight off germs if you come into contact with them in the future.

Some vaccines come in just 1 dose. Others require 2 or more doses to fully protect you from infection. After you get a vaccine, it usually takes a couple of weeks before you are fully protected. This is because it takes time for your immune system to make the antibodies.

Why should I get vaccinated? — Getting vaccinated can help keep you from getting certain infections. If you do get an infection, being vaccinated can also keep you from getting severely ill.

In some cases, being vaccinated also helps protect other people around you. For diseases that can spread from person to person, the goal of vaccines is to get to "herd immunity." Herd immunity is when enough people are immune to a disease that it can no longer spread easily. To get to herd immunity, lots of people need to get vaccinated. This helps protect people who cannot get vaccinated for some reason.

Are vaccines safe? — Yes. Before a vaccine is approved for use, it has to go through a specific process to test it for safety. This involves running "clinical trials" with lots of people who volunteer to try the vaccine. During these trials, researchers study how well the vaccine works and how many people had side effects. The results are reviewed by doctors and other experts who do not work for the drug companies that made the vaccine. These experts must agree that the vaccine is safe and effective enough to be given to the public.

There are a lot of myths about vaccines, and it can be hard to tell what is true and what is false. Here are some important things to know:

Vaccines work. The number of people who got childhood diseases, like measles or whooping cough, went way down after vaccines for those diseases became available. When there is an outbreak of one of these diseases, it mostly affects people who did not get the vaccine. Sometimes, a person who was vaccinated does get an infection. But when this happens, their illness is usually milder than it would have been if they didn't get the vaccine.

Vaccines do not make you sick. In some cases, vaccines can cause mild side effects like a fever. But these side effects are temporary, and they do not mean that the vaccine gave you an infection.

It is not better to get immunity "naturally." It's true that actually having an infection can protect you from getting it again in the future. But it's not a good idea to try to get infected on purpose for this reason. Even if you are in good health, it's possible to get very sick or even die from some infections. You could also spread the infection to other people who are at risk of getting seriously ill.

Vaccines do not contain toxic ingredients. Some people worry about certain ingredients found in some vaccines, such as aluminum. But the amount of aluminum in vaccines is so tiny that it cannot harm you.

Vaccines do not cause autism. After doing many careful studies, scientists have not found any link between vaccines and autism. Many years ago, one very small study said there was a link between autism and vaccines. But that study turned out to be false.

Do vaccines cause side effects? — They can. Often vaccines cause no side effects, but sometimes they do. When side effects happen, they can include:

Redness, mild swelling, or soreness where you got the shot

A mild fever

A mild rash

Headache or body aches

These side effects do not mean you are sick, just that your immune system is responding to the vaccine.

Vaccines also sometimes cause more serious side effects, such as severe allergic reactions. But serious side effects are rare.

What vaccines should I get, and when? — Your doctor or nurse can talk to you about what vaccines you should get and when to get them.

In general, people need different vaccines at different times:

Infants and children usually need vaccines against infections that can happen at any time in life. Childhood vaccines include those against measles, mumps, rubella, and polio.

Children older than 6 months and adults need a flu vaccine every year. Some adults also need a vaccine against the most common type of pneumonia (a lung infection).

Adults sometimes need vaccines that they never got as children.

Travelers sometimes need vaccines against infections that exist in the area they are visiting.

When a new infection spreads, people might need to get a new vaccine. For example, vaccines for the virus that causes coronavirus disease 2019 (COVID-19) became available starting in late 2020.

There are some situations where a person should not get a vaccine. For example, certain vaccines should not be given to people whose immune system is weaker than normal, or people who are allergic to specific ingredients.

What if I want to get pregnant? — If you want to get pregnant, ask your doctor or nurse if you need any vaccines. Some vaccines must be given before pregnancy. Others are important to get during pregnancy. Getting the right vaccines before and during pregnancy can protect you and your baby from serious infections.

What if I have other questions? — It's normal to have questions, especially about new or unfamiliar vaccines. Your doctor or nurse can help answer your questions or direct you to sources you can trust.

Be careful with information you find on the internet or social media. In some cases, it can be hard to tell what is true and what is false. This is especially dangerous if people share health information that is not based on science or evidence.

You can find more information about vaccines through the United States Centers for Disease Control and Prevention (CDC): www.cdc.gov/vaccines/index.html.

More on this topic

Patient education: Vaccines for adults (The Basics)
Patient education: Flu vaccine (The Basics)
Patient education: COVID-19 vaccines (The Basics)
Patient education: Vaccines for travel (The Basics)
Patient education: Vaccines for adults with HIV (The Basics)
Patient education: Vaccines for babies and children age 0 to 6 years (The Basics)
Patient education: Vaccines for children age 7 to 18 years (The Basics)
Patient education: Tdap vaccine (The Basics)
Patient education: Human papillomavirus (HPV) vaccine (The Basics)
Patient education: Vaccines and pregnancy (The Basics)

Patient education: Vaccines for adults (Beyond the Basics)
Patient education: Why does my child need vaccines? (Beyond the Basics)
Patient education: Vaccines for infants and children age 0 to 6 years (Beyond the Basics)
Patient education: Vaccines for children age 7 to 18 years (Beyond the Basics)
Patient education: Human papillomavirus (HPV) vaccine (Beyond the Basics)
Patient education: Vaccination during pregnancy (Beyond the Basics)

This topic retrieved from UpToDate on: Jan 02, 2023.
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