Table 2.
Various Types of VVaccines Categorized by the Antigen Used in the Preparation.
| Vaccine | Structure | Comments |
|---|---|---|
| Virus vaccines | ||
| Attenuated | Virus is weakened by passing through animal or human cells, until genome mutates and unable to cause disease | Inexpensive, rapid production Live vaccine, small chance of disease, replicates Needs cold chain Induces strong long-lasting T cell & B cell immune response Good for attaining herd immunity in the community Vaccine in use: BCG, Smallpox, MMR, Chickenpox, Rotavirus, Yellow fever, Polio (OPV) |
| Inactivated | Virus inactivated with formaldehyde or heat | Noninfectious, cannot cause disease. Can be freeze dried, no cold chain needed Needs adjuvant for immune response Can cause TH2 cell skewed response (ADE) Vaccines in use: Polio (IPV), HAV, Rabies. Hepatitis A, rabies, Flu. Candidate COVID-19 vaccine: PiCoVacc (Sinovac Biotech) |
| Nucleic acid vaccines | ||
| DNA vaccine | Gene encoding antigenic components (Spike protein) | Safe, cannot cause disease. Yet unproven in practice. Can cause TH2 cell skewed response (ADE) when used alone. Highly immunogenic, generate high titre neutralizing antibodies when given with inactivated vaccine. Electroporation device needed for delivery Candidate COVID-19 vaccine: INO-4800 (Inovio Pharma, CEPI, Korean Institute of Health, International Vaccine Institute) |
| RNA vaccine | mRNA vaccine for spike protein, with a lipid coat | Safe, cannot cause disease, Can cause TH2 cell skewed response, Yet unproven in practice Candidate COVID-19 vaccine: mRNA-1273 (Moderna/NIAID). BNT162 (a1, b1, b2, c2) (BioNTech/Fosun Pharma/Pfizer) |
| Viral vector vaccines | ||
| Replicating | An unrelated virus like measles or adenovirus is genetically engineered to encode the gene of interest | Safe, Induces strong T cell and B cell response, Vaccines in use: Hepatitis B, pertussis, pneumonia caused by S. pneumoniae, HPV, Hib (Haemophilus influenza) |
| Nonreplicating | An unrelated virus like measles or adenovirus (with inactive gene) is genetically engineered to encode the gene of interest | Safe, Need booster shots to induce long-term immunity, No vaccine licensed yet Candidate COVID vaccine: Ad5-nCoV (CanSino Biological Inc./Beijing Institute of Biotechnology). ChAdOx1-nCoV-19 (University of Oxford) |
| Protein-based vaccines | ||
| Subunit | Antigenic components (spike protein) are generated in vitro and harvested for vaccine | Safe, Need multiple dosing and adjuvants |
| Virus-like particles | Empty virus shells with no genetic material | Safe, Strong immune response, Difficult to manufacture |
ADE, antibody-dependent enhancement.