A retrospective study from Argentina has demonstrated the efficacy of the first dose of Sputnik Light coronavirus vaccine among the elderly. Sputnik Light is the first component (rAd26) of the Gam-COVID-Vac (Sputnik V) vaccine, a recombinant adenovirus (rAd)-based vaccine. Results of the study are published in the journal EClinicalMedicine published by The Lancet.¹

Persons, aged 60-79 years, who had registered themselves in the online vaccination system of the Province of Buenos Aires, Argentina, from December 29, 2020 to March 21, 2021 were included in the study. Those who had earlier tested positive for SARS-CoV-2 (RT PCR or antigen test) or had received the second component also or two doses of any vaccine were excluded from the trial. The study participants were further categorised into two age subgroups of 60-69 years and 70-79 years. 

415,995 of the individuals in the study had taken the first dose of the Sputnik vaccine. Of these, 40387 were aged 60-79 years. Their outcomes in terms of new RT PCR-confirmed SARS-CoV-2 infections, hospitalizations and mortality until 83 days of vaccination were compared to 38978 unvaccinated individuals. The vaccine was found to be 78.6% effective preventing new Covid-19 infections at 21 to 83 days post-vaccination. Hospitalizations reduced by 87·6% and deaths reduced by 84·8%. The efficacy of the vaccine was consistent in all participants with or without comorbidities across all subgroups.

Sputnik V vaccine is a vector-based heterologous (rAd26 and rAd5) two-dose vaccine administered at a gap of 21 days. Earlier this year in February, interim results of a phase III trial conducted in Russia published in The Lancet had shown that two doses of the vaccine could prevent 91.6% of symptomatic infections, while one dose prevented 87.4% at 14 days after the vaccine. From 15 to 21 days after the first dose, efficacy against moderate or severe Covid-19 was 73.6%. Notably, the efficacy of the vaccine in persons above 60 years of age was 91.8%.

To gain maximum benefit from the vaccine, both doses of the vaccine are essential. Since one dose of the vaccine has shown nearly 79% efficacy in preventing new infections and decreasing need for hospitalization and mortality, the second dose can be delayed in the event of vaccine shortage, according to the study authors; “delaying the second dose will allow vaccination of a higher proportion of the population in a panorama of vaccine scarcity”, they further add.

Yesterday, Sputnik Light vaccine was given the go-ahead to conduct trials on the Indian population by the Drug Controller General of India (DCGI) following recommendations of the Subject Expert Committee. Sputnik V vaccine was granted emergency use approval in India in April this year. As reported, till now 8- 9 lakh doses of Sputnik V have been administered in the country.

Reference

1. González S, et al. Effectiveness of the first component of Gam-COVID-Vac (Sputnik V) on reduction of SARS-CoV-2 confirmed infections, hospitalisations and mortality in patients aged 60-79: a retrospective cohort study in Argentina. EClinical Medicine, Published September 12, 2021.