Effectiveness of Sputnik V, Qazvac, Hayat-Vax, and Coronavac Vaccines in Preventing COVID-19 in Kazakhstan, February-September 2021

BACKGROUND In February 2021 Kazakhstan began offering COVID-19 vaccines to adults. Breakthrough SARS-CoV-2 infections raised concerns about real-world vaccine effectiveness. We aimed to evaluate effectiveness of four vaccines against SARS-CoV-2 infection.METHODS We conducted a retrospective cohort analysis among adults in Almaty using aggregated vaccination data and individual-level breakthrough COVID-19 cases (≥14 days from second dose) using national surveillance data. We ran time-adjusted Cox-proportional-hazards model with sensitivity analysis accounting for varying entry into vaccinated cohort to assess vaccine effectiveness for each vaccine (measured as 1-adjusted hazard ratios) using the unvaccinated population as reference (N=565,390). We separately calculated daily cumulative hazards for COVID-19 breakthrough among vaccinated persons by age, and vaccine month.RESULTS From February 22 to Sept 1, 2021 in Almaty, 747,558 (57%) adults were fully vaccinated (received two doses), and 108,324 COVID-19 cases (11,472 breakthrough) were registered. Vaccine effectiveness against infection was 78% (sensitivity estimates: 74–82%) for QazVac, 77% (72–81%) for Sputnik V, 71% (69–72%) for Hayat-Vax, and 69% (64–72%) for CoronaVac. Among vaccinated persons, the 90-day follow-up cumulative hazard for breakthrough infection was 2·2%. Cumulative hazard was 2·9% among people aged ≥60 years versus 1·9% among persons aged 18–39 years (p<0·001), and 1·2% for people vaccinated in February–May versus 3·3% in June–August (p<0·001).CONCLUSION Our analysis demonstrates high effectiveness of COVID-19 vaccines against infection in Almaty similar to other observational studies . Higher cumulative hazard of breakthrough among people >60 years of age and during variant surges warrants targeted booster vaccination campaigns.Funding Information: None to declare. Declaration of Interests: None to declare. Ethics Approval Statement: Ethics Approval was waved by the United States CDC for the following reason: Not Research - Public Health Surveillance.