The impact of Omicron on the COVID-19 vaccines: A review

The moment SARS-CoV-2 seemed to be receding; there was an uncertain emergence of Omicron variant which rapidly spread to all the 6 continents of the globe. The large number of genomic mutations has helped Omicron to evolve and become highly transmissible and escape the natural or vaccine-induced immune response. Until now, the Omicron has evolved into 5 unique lineages namely BA.1, BA.2, BA.3, BA.4, BA.5, and over 1000 sub-lineages. Despite vigorous COVID-19 immunisation programmes, India has been constantly being affected with emergence of new Omicron variants. In contrast to recovered patients following vaccination and breakthrough cases following a second dose against the Omicron variety, our recent research of naive Covishield vaccines showed declining immune response. The finding of this study and other studies with Covaxin depicted less immune response against Omicron post second dose of vaccination. This necessitates the administration of a preventive dose to improve immunity. There was surge in the COVID-19 cases with BA.5, BA.4, BF.7, BQ.1, XBB, and JN.1 infection which has greater transmissibility and vaccine efficacy remarkably dropped. Hence along with administration of booster dose, there is need to tweak the currently available vaccines with these SARS-CoV-2 variants. These types of modified boosters could provide enhances protection against SARS-CoV-2 infection.