Abstract
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has thrown a challenge to the scientific community. Several interventions to stop or limit the spread of infection have failed, and every time the virus emerges, it becomes more contagious and more deadly. Vaccinating a significant proportion of the population is one of the established methods to achieve herd immunity. More than 100 COVID-19 vaccines have been designed and tested against the virus. The development of a new vaccine takes years of testing, but due to the pandemic, healthcare authorities have given emergency use authorization for a few vaccines. Among them are BioNTech and Moderna vaccines (mRNA based); ChAdOx1, Gam-COVID-Vac, Janssen vaccines (vector-based); CoronaVac, COVAXIN (virus inactivated); and EpiVacCorona vaccine (viral peptide). Mixtures of vaccines are also being tested to evaluate their efficacy against mutant strains of SARS-CoV-2. All these vaccines in clinical trials have shown robust production of neutralizing antibodies sufficient to prevent infection. Some of the vaccinated people reported serious complications. However, no definitive relationship could be established between vaccination administration and the occurrence of these complications. None of the COVID-19 vaccines approved to date have been found to be effective against all of the SARS-CoV-2 variants.