Efficacy of the Vaccines, Their Safety, and Immune Responses against SARS-CoV-2 Infections

Abstract

The search for vaccines has been a high priority since the worldwide COVID-19 pandemic was declared. Currently, mRNA-based vaccines, adenovirus-based vaccines, inactivated virus vaccines, and other vaccine platforms are all employed to combat the SARS-CoV-2 virus. BNT162b2 and mRNA-1273 are mRNA-based vaccines. The vaccination appears to be effective against SARS-CoV-2 strains that have emerged since the first study. They have primarily minor side effects, and there are no major safety concerns. Adenovirus-based vaccines are delivered by genetic cargo that is based on non-replicating adenovirus vectors that can increase immune response without the need of adjuvants. This is the case for Ad26.CoV2.S, ChAdOx1 nCoV-19/AZD1222, Gam-COVID-Vac/Sputnik V andAd5-based COVID-19 vaccine. There have been no known incidences of allergy to adenovirus vaccines, unlike mRNA vaccines. Inactivated virus vaccines are a common form of vaccine that has been used for decades. The goal is to render the virus non-infectious while preserving immunogenicity with high-quality antigens in order to trigger an immune response. The researched formaldehyde-inactivated whole-virus SARS-CoV2 vaccine (CoronaVac), as well as WIV04 and HB02, utilize this sort of vaccine formulation. A recombinant protein nanoparticle vaccine named NVX-CoV2373 is made up of trimeric spike glycoproteins with a potent Matrix-M1 adjuvant. Against the variant B.1.1.7 (Alpha), the vaccine appeared to be very effective. Vaccine efficacy against the B.1.351 (Beta) strain, on the other hand, proved to be lower.