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

Background: A first-dose of various vaccines provides acceptable protection against infections by SARS-CoV-2 and evolution to the most severe forms of COVID-19. The recombinant adenovirus (rAd)-based vaccine, Gam-COVID-Vac (Sputnik V), was proven efficacious but information about effectiveness in the real-world setting is lacking. The aim of our study was to investigate the association between the rollout of the first component (rAd26) of Gam-COVID-Vac and PCR-positive tests, hospitalisations and deaths. Methods: We conducted a retrospective cohort study which analyzed individuals aged 60-79 who self-registered in the online vaccination system of the Province of Buenos Aires, Argentina, from December 29, 2020 to March 21, 2021. Exclusion criteria were having a previous positive RT-PCR or antigen tests for SARS-CoV-2, having received other vaccines, or two doses of any vaccine. Proportions of new laboratory-confirmed SARS-CoV-2 infections, hospitalisations and deaths until 83 days of vaccination were compared between vaccinated and unvaccinated subjects. Vaccine effectiveness for the three outcomes was calculated as (1-OR) x 100. Kaplan-Meier cumulative incidence curves were constructed. Findings: During the study period 415995 registered subjects received the first component of Gam-COVID-Vac; 40387 belonged to the 60-79 age group, and were compared to 38978 unvaccinated. Vaccine effectiveness for preventing laboratory-confirmed infections was 78.6% [CI95% 74.8 - 81.7]; and for reducing hospitalizations and deaths was, respectively, 87.6% [CI95% 80.3 - 92.2] and 84.8% [CI95% 75.0 - 90.7]. Effectiveness was high across all subgroups. Interpretation: Similarly to other vaccines, the administration of one dose of Gam-COVID-Vac was effective for a wide range of COVID-19-related outcomes. (C) 2021 The Author(s). Published by Elsevier Ltd.

Automated summary

The study investigated the effectiveness of the first component of Gam-COVID-Vac in preventing infections, hospitalizations, and deaths in the elderly population, showing high effectiveness in reducing all three outcomes.