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.

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 vaccine month.RESULTSFrom February 22 to Sept 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 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).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.What is already known on this topicPlenty of data are published on effectiveness of mRNA vaccines; however, these vaccines were not widely available in many low- and middle-income countries in 2021.There are no real-world effectiveness studies on several vaccines available in the Central Asia region, including QazVac vaccine, an inactivated vaccine developed by Kazakhstan.Understanding how these vaccines are performing outside of clinical trials is critical for the COVID-19 response and lack of published data can contribute to vaccine hesitancy.What this study addsOur study demonstrated that at the population-level the four vaccines against COVID-19 used in Kazakhstan were effective at preventing SARS-CoV-2 infection.Vaccination reduced the risk of infection by 76% and prevented over 100,000 cases of SARS-CoV-2 infection in Almaty, the country’s most populous city.This is also the first study that demonstrated high vaccine effectiveness in real-world conditions of QazVac, developed in Kazakhstan.How this study might affect research, practice or policyPolicy makers in Kazakhstan and the Central Asia region need data on vaccines provided in the region to update evidence-based vaccine guidelines for different populations.

Relevance. In 2018 over 151 000 cases of whooping cough were reported worldwide. In the Republic of Kazakhstan the incidence of whooping cough has always remained relevant. The incidence is recorded mainly among children under 14 years of age, whose share is 96–100% of the total incidence in certain years. It should also be noted that 82,9–96% of sick people are not vaccinated against whooping cough. Aims. Assessment of the duration of protection after vaccination against pertussis infection in Kazakhstan using antibodies against pertussis toxin (PT) and (IgA and IgG) as a specific marker of pertussis infection or vaccination in children and adolescents in the cities of the Republic of Kazakhstan: Aktobe, Karaganda, Taldykorgan, Shymkent for evaluation appropriate age for booster vaccination. Materials and methods. For the study included medical organizations in the cities of Aktobe, Karaganda, Taldykorgan, Shymkent. Participants aged 10–14 years who were hospitalized in children's hospitals and 15–18 years old who visited polyclinics were invited to participate in the study. Each city has 1 children's hospital (4 in total) and 2 polyclinics (8 in total). A total of 520 people of different age groups participated. Study period: February 2021 – October 2021. Inclusion criteria were such aspects as: age from 10 years to 18 years 11 months 29 days, informed consent obtained from parents or guardian(s) and patient consent, enrollment after visiting the clinic, the presence of documented evidence of immune status. An association between two qualitative variables is considered statistically significant if the p-value calculated using     the Chi-squared test is less than 0.05. Results. Among 520 participants aged 10–14 years – 200 (38.5%) and 15–18 years – 320 (61.5%), including boys – 284 (54.6%), girls – 236 (45.4%). The largest number of study participants was aged 15, 16 and 17 years, 10 participants (1.9%) had periods of prolonged coughing in the past 6 months. The first, second and third pertussis vaccines were received by 100% of children. The first and second vaccine for all children was the Adsorbed Diphtheria-Tetanus-Pertussis Vaccine (DPT). The third vaccine for 519 children was also DPT, for one child – AbDPT, due to the transition to a cell-free vaccine from the second half of 2013. The additional vaccine scheduled at 18 months of age was given to 519 participants (99.8%), of which 517 children (99.6%) received DPT and two children (0.4%) DPT. Just over half of the children (276 or 53.1%) also received the whooping cough vaccine at age 6. In biological blood samples of 17 participants (3.3%). antibodies of the IgA class were detected in 245 samples (47.1%) – antibodies of the IgG class. Of the 17 participants with IgA antibodies, 15 also tested positive for IgG. In total antibodies of the IgA and IgG classes were detected in 247 participants which amounted to 47.5%. Conclusions. This study showed the duration of protection after pertussis vaccination in Kazakhstan among different age groups. In total, antibodies of the IgA and IgG classes were detected in 247 participants out of 520 which amounted to 47.5%. IgA antibodies were detected in biological blood samples in 17 participants (3.3%), IgG class antibodies in 245 samples (47.1%). The prevalence of IgA antibodies was statistically significantly higher among older children and among children who had respiratory symptoms in the 6 months prior to the study. The prevalence of IgG antibodies was statistically significantly higher among children vaccinated against whooping cough at the age of 6 years (47.1%) and at the age of 10–14 years (56.2%) than in the age group of 15–18 years (43.8%) and also significantly higher among those, who share a bedroom with other family members compared to children living in separate rooms. Thus an increase in whooping cough and a decrease in protective vaccine immunity among older age groups can be stated which raises concerns about transmission of the infection in the home to vulnerable children and the need to strengthen vaccination strategies.

No abstract

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 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 vaccine month. Results From February 22 to Sept 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 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&lt; 0.001), and 1.2% for people vaccinated in February–May versus 3.3% in June–August (p&lt; 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 &gt;60 years of age and during variant surges warrants targeted booster vaccination campaigns. Disclosures All Authors: No reported disclosures.