Table 1.

Advantages and disadvantages of various types of COVID19 vaccines in development

Vaccine type	COVID-19 vaccines furthest in development/approved	Advantages	Disadvantages
Inactivated virus	SinoVac (CoronaVac + aluminum) SinoPharm (Inactivated whole virus SARS-CoV-2 + aluminum)	Entire virus, with all antigens presented Prior experience and technology – e.g., quadrivalent influenza vaccine Easier storage – does not need to be frozen	Need adjuvants to boost Poor inducers of CD8 + T-cell immunity Hard to mass-produce Large batches of live virus pose biosecurity risk
Protein subunits	Novavax (NVX-CoV2373) Vector Institute (EpiVacCorona)	Can focus on antigens that generate neutralizing antibodies Does not introduce intact pathogen	Produced ex vivo, may not retain post-translational modifications or conformation Not efficiently presented Lower humoral and cellular response Require adjuvants to boost
Replication incompetent adenoviral vector	AstraZeneca (ChAdOx1 nCoV-19; AZD1222) Johnson & Johnson (Ad26.COV2.S) CanSino Biologics (Ad5-nCoV) Gamaleya (Sputnik V)	Replication-defective, no new viral particles Avoids intact pathogen Mimics natural infection Elicits humoral and cellular immunity	Anti-vector immunity may interfere Lower efficacy if prior anti-vector immunity exists
DNA	Inovio (INO-4800)	Mimic natural infection Elicits strong humoral and cellular immunity Avoids introducing pathogen Easier to mass-produce	Delivery into cell nucleus
mRNA	Moderna (mRNA-1273) Pfizer-BioNTech (BNT162b2)	Delivery into cytoplasm Unable to integrate into host genome Elicit strong humoral and cellular immunity Avoids anti-vector immunity Avoids introducing pathogen Easier to mass-produce	Fragile – easily degraded Needs lipid nanoparticle for delivery Frozen for storage