Covaxin, Covishield & Sputnik V & their efficacy rate

June 7: Amid the 2nd wave of coronavirus and the huge death toll, the only way to protect one is to get vaccinated. The India government has approved the emergency use of 3 vaccines as of now. These are Covaxin, Covishield and Sputnik V. There are ofcourse diverse opinions put forward by experts as regards which vaccine is most effective in its fight against Covid-19.

Covaxin: India^‘s indigenous COVID-19 vaccine by Bharat Biotech is developed in collaboration with the Indian Council of Medical Research (ICMR) – National Institute of Virology (NIV). The vaccine is developed using Whole-Virion Inactivated Vero Cell derived platform technology. Inactivated vaccines do not replicate and are therefore unlikely to revert and cause pathological effects. Analysis from the National Institute of Virology indicates that vaccine-induced antibodies can neutralize the UK variant strains and other heterologous strains.

The preliminary data of Phase 3 trials shows that Covaxin has an efficacy rate of 81 percent. The duration between the two doses of Covaxin is 28 days to 42 days.

Covishield: The Oxford Astra Zeneca Vaccine Covishield is produced by the Serum Institute of India (SII). It is a recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 Spike (S) glycoprotein. Following administration, the genetic material of part of corona virus is expressed which stimulates an immune response. Clinical trials have shown that after 2 doses of the vaccine almost all recipients developed antibodies. Data as of now shows that that the vaccine offers protection against the B 1.1.7 (UK), B.1.167.1  and P.1 (Brazil) variant.

Covishield is also a two doses shot which is administered 12 to 16 weeks apart. It has an efficacy of 70 percent.

Sputnik V: It is manufactured by the Gamalaya Institute, Moscow (Russia). Gam-COVID-Vac was initially approved for distribution in Russia and then in 59 other countries including India (as of April 2021) on the preliminary results of Phase I–II studies eventually published. The recombinant adenovirus types 26 and 5 are both used as vectors in the vaccine. They were biotechnology-derived and contain the SARS-CoV-2 S protein cDNA. Both of them are administered into the deltoid muscle: the Ad26-based vaccine is used on the first day and the Ad5 vaccine is used on the 21st day to boost immune response.

Two slightly different versions of the vaccine are administered 21 days apart. It has an efficacy of 92 percent.

Whatever may be the efficacy level, as per the guidelines of the Ministry of Health and Family Welfare (MOHWF), Government of India, individuals were asked to take the jab to get protected from the deadly Covid-19. All of them are approved and meet safety standards. Instead of trying to make a comparative study of the now available vaccines in India, the health ministry has advised to go for the shots, whichever is readily available. But there is a word of caution- never mix the two doses of vaccines.