Effectiveness of four vaccines in preventing SARS-CoV-2 infection in Almaty, Kazakhstan in 2021: retrospective population-based cohort study

Abstract

BackgroundIn 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.MethodsWe conducted a retrospective cohort analysis among adults in Almaty using aggregated vaccination data and individual-level breakthrough COVID-19 cases (≥14 days from 2nd 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 vaccination month.ResultsFrom February 22 to September 1, 2021, in Almaty, 747,558 (57%) adults were fully vaccinated (received 2 doses), and 108,324 COVID-19 cases (11,472 breakthrough) were registered. Vaccine effectiveness against infection was 79% [sensitivity estimates (SE): 74%–82%] for QazVac, 77% (SE: 71%–81%) for Sputnik V, 71% (SE: 69%–72%) for Hayat-Vax, and 70% (SE: 65%–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).ConclusionOur 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.

Factors associated with COVID-19 vaccine confidence among primary care providers in Kazakhstan, March–April 2021

“…We found that less than half of providers believed in safety and effectiveness of the most common COVID-19 vaccines available in Kazakhstan at that time. Low trust in COVID-19 vaccine safety and effectiveness could have been influenced by the lack of published data on the predominant COVID-19 vaccines available in Kazakhstan, Sputnik V, and QazVac (43)(44)(45). Most literature on COVID-19 vaccines was predominantly in English, as are most scientific publications, and therefore likely not easily accessible to the majority of healthcare providers in Kazakhstan (46), where 97% of the population speaks Russian and 80% speaks Kazakh (47).…”

Attitude toward vaccination against COVID-19 and acceptance of the national “QazVac” vaccine in the Aktobe city population, West Kazakhstan: A cross-sectional survey

“…Vaccination started in February 2021, and mandatory vaccination was required for health providers, teachers of secondary schools, and police officers; then, as access to vaccines expanded, it became compulsory for students and employees of higher and secondary educational institutions. Several types of vaccines were available to the public: Kazakhstan’s QazVac, Russian Sputnik V and Sputnik Lite, Chinese Hayat-Vax (Sinopharm) and CoronaVac, and later Pfizer’s Comirnaty vaccine (USA) for vaccination of adolescents, pregnant women and patients of maternity wards [ 14 ]. It is commonly accepted that several types of vaccines allow for more rapid collective immunity.…”

The impact of Gam-COVID-Vac, an Adv5/Adv26 COVID-19 vaccine, on the biomarkers of endothelial function, coagulation and platelet activation

“…Starting from late 2020, this vaccine has been used in 71 countries spanning Latin America, Africa, and Asia, including Kazakhstan. Between February and September 2021, Kazakhstan’s COVID-19 vaccination initiative predominantly utilized Gam-COVID-Vac, with over 85% of vaccine recipients having been administered Sputnik-V [ 8 ]. During this extensive vaccination rollout, we embarked on a study to assess the safety, potential side effects, and immune reactions to Gam-COVID-Vac among a group with varied prior exposure to COVID-19 [ 9 ].…”