Covid-19 Vaccines Available in India

The present review covers the list of approved vaccines available in India, i.e., Covaxin, Covishield, and Sputnik-V. Covaxin's code name is BBV152. Covaxin was prepared by Hyderabad- based Bharat Biotech International Ltd. in collaboration with the National Institute of Virology (NIV) and ICMR. The effectiveness of Covaxin was found to be 78-81%. Covishield, which is available by code name AZD1222, was developed by the SII, Oxford University, and AstraZeneca. Covishield's effectiveness was found to be 90%. The time gap between the two doses of Covaxin and Covishiled is 4-6 weeks and 12-16 weeks, respectively. One more vaccine, i.e., Sputnik V, by the code name rAd26-S and rAd5-S, was developed by Gamaleya Research Institute of Epidemiology and Microbiology, which involves an interval gap of 21 days between the two doses. Covaxin releases Anti-SARS-CoV-2 IgG, which is specific to RBD (receptor-binding domain) protein, whereas a high degree of antibody response dissipates on the 28th day of vaccination. The protective efficacy of Sputnik-V was found to be ±92.2% (95% CI ±82.6-92.3), while that of Covishield was found to be ±90 % (95% CI 68.2-98.0±, p = 0.01) 2-standard dose: (61.2%, 95% CI 42.2-76.1±). In the case of Covaxin, the rate of seroconversion was found to be 93.9% (95% CI 85.2-98.2) in the 3-μg group and 97.2% (95% CI 93.1-105.1) in the 6-μg group. No significant difference was observed in local or systemic adverse reactions of the vaccine in the groups of 3 μg and 6 μg. The protective efficacious dose of Covaxin has not yet been identified. The cellular response median SFCs PBPMC of Covishield at the standard dose in the age group of 18-55 years was found to be±1201; 55-70 years: ±758 and ≥75 years: ±975. No significant increase was observed in the per million peripheral mononuclear cells (PBPMC) after administration of the booster dose of Covishield vaccine (p = 0.45 in paired student's t-test on the 28th day vs. the 42nd day). The cellular response to Sputnik V was found to be 100%. Higher levels of T cells CD8+, CD4+ T cells, and IFN- γ secretion were reported in all volunteers who had undergone vaccination. Cell proliferation was found as follows: CD⁴⁺: +1.5% and CD⁸⁺ : +1.3% in the lyophilized formulation and CD4+ : + 2.6% and CD8+ : +1.5% in the frozen formulation. Antigen-specific IgG geometric mean titer (GMT) levels of Covishield were found to be highest on the 28th day with 160 geometric mean ELISA units (GMEU).