| Platform type | Description | COVID-19 vaccine examples* | Other vaccine examples | Comments |
| Whole virus vaccines |
| Inactivated vaccines | - Produced by growing SARS-CoV-2 in cell culture then chemically inactivating the virus.
- Often combined with an adjuvant to stimulate immune response.
| - CoronaVac (Sinovac)
- BBIBP-CorV/HB02 (Covilo, Sinopharm [Beijing])
- Covaxin (Bharat Biotech)
| - Hepatitis A vaccine
- Inactivated poliovirus vaccine
| - Immune response targets multiple viral antigens.
|
| Live attenuated vaccines | - Produced by developing weakened versions of wild-type SARS-CoV-2 through genetic modification or growth in adverse conditions.
| - COVI-VAC (Codagenix/Serum Institute of India) – in early trials
| - Measles, mumps, rubella vaccine
- Varicella vaccine
| - Immune response targets multiple viral antigens.
- Can be administered intranasally and thus might induce mucosal immune response at the site of viral entry.
- Theoretic concern about reversion to or recombination with wild-type virus.
- Not appropriate for immunocompromised individuals.
|
| Viral component vaccines |
| mRNA vaccines | - Consist of mRNA encoding target gene.
- Once administered, mRNA is translated into target protein, which elicits immune response.
| - BNT162b2 (Pfizer-BioNTech vaccine)
- mRNA-1273 (Moderna vaccine)
| | - mRNA remains in cell cytoplasm, does not enter nucleus, and does not interact with or integrate into recipient DNA.
- May require low temperature storage.
|
| Vector virus vaccines (both replication incompetent and competent) | - Uses a different virus (not SARS-CoV-2) as a vector or carrier that expresses the viral protein that is the intended target.
| | | - Pre-existing immunity to the vector can attenuate vaccine immunogenicity (thus, viral vectors that are uncommon in humans, animal virus vectors, or vectors that do not induce self-immunity are preferred).
|
- Replication-incompetent vector vaccines
| - Viral vector has been engineered not to replicate.
| - Ad26.COV2.S (Janssen/Johnson & Johnson)
- ChAdOx1 nCoV-19/AZD1222 (AstraZeneca)
- Gam-COVID-Vac Sputnik V (Gamaleya Institute)
- Ad5-nCoV (CanSino)
| - Ad26.ZEBOV/MVA-BN-Filo (an Ebola virus vaccine)
| - Failure of the vector to reproduce could theoretically reduce potential adverse events that could occur with replicating vectors.
- Example vectors include adenovirus, modified vaccinia Ankara (MVA), human parainfluenza virus, influenza virus, adeno-associated virus (AAV), and Sendai virus.
|
- Replication-competent vector vaccines
| - Viral vector is derived from attenuated or vaccine strains of viruses.
| - DelNS1-2019-nCoV-RBD-OPT1, an intranasal flu-based RBD vaccine (University of Hong Kong) – in trials
| - rVSV-ZEBOV (an Ebola virus vaccine)
| - Often result in more robust immune response compared with replication-incompetent vectors (stimulate innate immune response).
- Can be administered intranasally and thus might induce mucosal immune response at the site of viral entry.
- Example vectors include measles vaccine strains, influenza virus, vesicular stomatitis virus (VSV), and Newcastle disease virus (NDV).
|
| Recombinant protein vaccines | - Composed of purified viral proteins that have been expressed in one of various systems (eg, insect and mammalian cells, yeast cells, plants).
| | - Human papillomavirus vaccines
- Hepatitis B vaccines
| - Stimulates immunity to the purified viral protein.
|
| DNA vaccines | - Consist of plasmid DNA that contain mammalian expression promotors and the target gene, so that the target protein is expressed in the recipient.
| | | - Are often of low immunogenicity.
- Need special delivery devices (eg, electroporators).
|
