Development of COVID 19 vaccine: A summarized review on global trials, efficacy, and effectiveness on variants

BACKGROUND AND AIMS: The emergence of SARS CoV2 or COVID 19 pandemic has shocking results on major global public health. This review aims to discuss the nine prominent COVID 19 vaccines with regard to their immunogenicity, efficacy, and effectiveness against the SARS CoV2 variants. METHODS: Electronic databases such as Medline/PubMed, EMBASE, Scopus, science websites, and Google scholar were accessed to retrieve the research published about COVID 19 vaccines. RESULTS: All the adverse impact ranging from mild to moderate in the clinical trials were analysed, however, there were less reports in which COVID 19 patients either developed severe reactions or died due to the different experimental vaccines. Moreover, SARS CoV2 variants like Delta could escape the immune response. CONCLUSION: Overall, the data suggest that the two doses of COVID 19 vaccines are extremely effective against the original SARS CoV2 virus, and also provide well protection against SARS CoV2 variants, especially in severe illnesses. However, a third dose of the COVID 19 vaccine (also said to be the booster dose) will be needed in some immune-compromised people.