Attenuated |
Preservation of native antigen; mimicking natural infection, well-established technology, robust B and T cell response |
Potential to cause infection, almost all given via syringe IM, cold chain storage, not suitable for immunocompromised |
Measles, Mumps, Polio (Sabin), Rotavirus, Yellow Fever, Bacillus Calmette–Guérin (BCG), Rubella, Varicella |
Inactivated |
Strong immune response with B cell more than T cell, waning immunity; safer than live attenuated virus—incapable of regaining pathogenicity; stable, relatively easy to scale manufacturing and distribution |
Potential epitope alteration by inactivation process |
Typhoid, Cholera, Hepatitis A virus, Plague, Rabies, Influenza, Polio (Salk) |
Toxoid |
Non-virulent, stable, and long lasting in storage |
Typically not robustly immunogenic, require regular booster doses, local site reactions, given by injection |
Diphtheria, Tetanus |
Subunit |
Readily modifiable, generally safe for immunocompromised, stable in storage and scalable in production. |
Relatively less immunogenic, often require adjuvant or conjugate. Development and manufacture are typically time-consuming |
Pertussis, Influenza, Streptococcus pneumoniae, Haemophilus influenzae type b |
Virus Like Particles (VLPs) |
Safe and well-tolerated; mimicking native virus conformation; unable to replicate; scalable and combinable with adjuvants |
Relatively complicated manufacturing process; lower stability, difficult downstream processing, high production costs, and sensitivity to environmental conditions |
Hepatitis B virus, Human Papillomavirus |
Viral vector |
Strong immune response; preservation of native antigen; mimicking natural infection |
Relatively complicated manufacturing process; risk of genomic integration; response dampened by pre-existing immunity against vector |
Ebola virus |
DNA/RNA |
Safe and well-tolerated; highly adaptable to new pathogen; native antigen expression |
Requirement of low temperature storage for RNA vaccine and transportation; potential risk of RNA-induced interferon response, risk of genomic integration for DNA vaccine. Cells do not easily take up large and polar nucleic acids. |
SARS-CoV-2 |