Role of available COVID-19 vaccines in reducing deaths and perspective for next generation vaccines and therapies to counter emerging viral variants: an update.

ABSTRACT

The COVID-19 disease wreaked havoc all over the world causing more than 6 million deaths out of over 519 million confirmed cases. It not only disturbed the human race health-wise but also caused huge economic losses and social disturbances. The utmost urgency to counter pandemic was to develop effective vaccines as well as treatments that could reduce the incidences of infection, hospitalization and deaths. The most known vaccines that could help in managing these parameters are Oxford-AstraZeneca (AZD1222), Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273) and Johnson & Johnson (Ad26.COV2.S). The effectiveness of AZD1222 vaccine in reducing deaths is 88% in the age group 40-59 years, touching 100% in the age group 16-44 years & 65-84 years. BNT162b2 vaccine also did well in reducing deaths due to COVID-19 (95% in the age group 40-49 years and 100% in the age group 16-44 years. Similarly, mRNA-1273 vaccine showed potential in reducing COVID-19 deaths with effectiveness ranging from 80.3 to 100% depending upon age group of the vaccinated individuals. Ad26.COV2.S vaccine was also 100% effective in reducing COVID-19 deaths. The SARS-CoV-2 emerging variants have emphasized the need of booster vaccine doses to enhance protective immunity in vaccinated individuals. Additionally, therapeutic effectiveness of Molnupiravir, Paxlovid and Evusheld are also providing resistance against the spread of COVID-19 disease as well as may be effective against emerging variants. This review highlights the progress in developing COVID-19 vaccines, their protective efficacies, advances being made to design more efficacious vaccines, and presents an overview on advancements in developing potent drugs and monoclonal antibodies for countering COVID-19 and emerging variants of SARS-CoV-2 including the most recently emerged and highly mutated Omicron variant.