Abstract
The B.1.1.529 (Omicron) variant of SARS-CoV-2 has rapidly spread with many variants like BA.1, BA.2, BA3., BA4., and BA5. With sublineages as well. It (Omicron) was first discovered in November 2021 and has become the predominant variant in several nations. Due to the sensitivity of infection and various other limitations like no particular real-time data for different age groups, there is a lack of information on the actual efficacy of vaccines against this variant. Limitations of data and reviews and the incidence of emergence rather than hospitalized people would result in an underestimation of the efficacy of vaccines against severe diseases. This systematic review was conducted by following PRISMA guidelines. Specific inclusion and exclusion parameters were strictly followed. Our studies show that a substantial number of people have received mRNA COVID-19 vaccine doses. The booster dose must be administered and obtained immediately before all efforts to stop the pandemic go to waste. Focusing on the primary vaccination is no longer sufficient.