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IMPORTANCEAlthough there are reports of COVID-19 vaccine implementation in real-world populations, these come from high-income countries or from experience with messenger RNA technology vaccines. Data on outcomes of vaccine deployment in low-or middle-income countries are lacking. OBJECTIVE To assess whether the pragmatic application of the 3 COVID-19 vaccines available in Argentina, 2 of which have no reports of evaluation in real-world settings to date, were associated with a reduction in morbidity, all-cause mortality, and mortality due to COVID-19. DESIGN, SETTING, AND PARTICIPANTS This cohort study used individual and ecological data to explore outcomes following vaccination with rAd26-rAd5, ChAdOx1, and BBIBP-CorV. To correct for differences in exposure times, results are shown using incidence density per 100 000 person-days from the start of the vaccination campaign (December 29, 2020) to the occurrence of an event or the end of follow-up (May 15, 2021). Participants included 663 602 people aged at least 60 years residing in the city of Buenos Aires, Argentina. Statistical analysis was performed from June 1 to June 15, 2021. MAIN OUTCOMES AND MEASURES Diagnosis of COVID-19 confirmed by reverse transcriptionpolymerase chain reaction, death from all causes, and death within 30 days of a diagnosis of COVID-19. Poisson regression models were fitted to estimate associations with all 3 outcomes. RESULTS Among 663 602 residents of the city of Buenos Aires included in the study, 540 792 (81.4%) were vaccinated with at least 1 dose, with 457 066 receiving 1 dose (mean [SD] age, 74.5 (8.9) years; 61.5% were female [n = 281 284]; 68.0% [n = 310 987] received the rAd26-rAd5 vaccine; 29.5% [n = 135 036] received ChAdOx1; 2.4% [n = 11 043] received BBIBP-CorV) and 83 726 receiving 2 doses (mean [SD] age, 73.4 [6.8] years; 63.5% were female [n = 53 204]). The incidence density of confirmed COVID-19 was 36.25 cases/100 000 person-days (95% CI, 35.80-36.70 cases/ 100 000 person-days) among those who did not receive a vaccine, 19.13 cases/100 000 persondays (95% CI, 18.63-19.62 cases/100 000 person-days) among those who received 1 dose, and 4.33cases/100 000 person-days (95% CI, 3.85-4.81 cases/100 000 person-days) among those who received 2 doses. All-cause mortality was 11.74 cases/100 000 person-days (95% CI, cases/100 000 person-days), 4.01 cases/100 000 person-days (95% CI, 3.78-4.24 cases/100 000 person-days) and 0.40 cases/100 000 person-days (95% CI, 0.26-0.55 cases/100 000 person-days). COVID-19-related-death rate was 2.31 cases/100 000 person-days (95% CI, 2.19-2.42 cases/100 000 person-days), 0.59 cases/100 000 person-days (95% CI, 0.50-0.67 cases/ 100 000 person-days), and 0.04 cases/100 000 person-days (95% CI, 0.0-0.09 cases/100 000 person-days) among the same groups. A 2-dose vaccination schedule was associated with an 88.1% (95% CI, 86.8%-89.2%) reduction in documented infection, 96.6% (95% CI, 95.3%-97.5%) reduction in all-cause death, and 98.3% (95% CI, 95.3%-99.4%) reduction in COVID-19-related (continued...

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Background Shortages of component two of Sputnik V vaccine (rAd5) are delaying the possibility of achieving full immunisation. The immunogenic response associated with the use of alternative schemes to complete the scheme was not explored. Methods We did two non-inferiority randomized clinical trials with outcomes measures blinded to investigators on adults aged 21–65 years, vaccinated with a single dose of rAd26 ≥ 30 days before screening and no history of SARS-CoV-2. Participants were assigned (1:1:1:1:1) to receive either rAd5; ChAdOx1; rAd26; mRNA-1273 or BBIBP-CorV. The primary endpoint was the geometric mean ratio (GMR) of SARS-CoV-2 anti-spike IgG concentration at 28 days after the second dose, when comparing rAd26/rAd5 with rAd26/ChAdOx1, rAd26/rAd26, rAd26/mRNAmRNA-1273 and rAd26/BBIBP-CorV. Serum neutralizing capacity was evaluated using wild type SARS-CoV-2 reference strain 2019 B.1. The safety outcome was 28-day rate of serious adverse. The primary analysis included all participants who received ≥ 1 dose. The studies were registered with NCT04962906 and NCT05027672. Both trials were conducted in Buenos Aires, Argentina. Findings Between July 6 and August 3, 2021, 540 individuals (age 56·7 [SD 7·3]; 243 (45%) women) were randomly assigned to received rAd5 ( n =150); ChAdOx1 ( n =150); rAd26 ( N =87); mRNAmRNA-1273 ( n =87) or BBIBP-CorV ( n =65). 524 participants completed the study. As compared with rAd26/rAd5 (1·00), the GMR (95%CI) at day 28 was 0·65 (0·51–0·84) among those who received ChAdOx1; 0·47 (0·34–0·66) in rAd5; 3·53 (2·68–4·65) in mRNA-1273 and 0·23 (0·16–0·33) in BBIBP-CorV. The geometric mean (IU/ml) from baseline to day 28 within each group increased significantly with ChAdOx1 (4·08 (3·07–5·43)); rAd26 (2·69 (1·76–4·11)); mRNA-1273 (21·98 (15·45–31·08)) but not in BBIBP-CorV (1·22 (0·80–1·87)). Interpretation Except for mRNA-1273 which proved superior, in all other alternatives non-inferiority was rejected. Antibody concentration increased in all non-replicating viral vector and RNA platforms. Funding The trials were supported (including funding, material support in the form of vaccines and testing supplies) by the Buenos Aires City Government.

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BackgroundVaricella (VZV) is one of the most frequent exanthematic diseases in childhood. In Argentina, around 150,000–180,000 total cases per year are registered; however, underreport exists and some 400,000 cases are estimated to occur annually. Varicella vaccine (VV) was included in the national immunization schedule (NIS) in 2015, with a 1-dose schedule administered at 15 months of age. The information provided by epidemiological surveillance is essential to evaluate the impact of public health decisions. Our objective was to describe and to compare the epidemiological situation of VZV infections in Argentina in two periods: pre (2010–2014) and post (2016–2017) vaccine introduction in NIS.MethodsDescriptive study. We compared cases and incidence rates (R) of VZV per 100,000 population (global and disaggregated by age) reported to the National Health Surveillance System; in pre (Pre-VV) and post-vaccination (Post-VV) periods. Data analysis of 2015 was excluded since it was considered a transition year.ResultsVaccination coverage for 2015 was 44.7%; 74.4% in 2016 and 75.5% in 2017. 728,392 cases of VZV were notified (R = 362,1) in Pre-VV period and 176,995 cases in Post-VV (R = 220.6), with a global incidence rate reduction of 39% (IC 95% =38.9–39.6; P < 0.001). Both 12–24 months of age and 2–4 years old groups (Pre-VV R 2,253 and Post-VV R 1,077; Pre-VV R 2,400 and Post-VV R 1,165, respectively) showed the greatest reductions in incidence rates (–52.2% [IC 95% 51.3–53] P <0.001 and –51.4% [IC 95% 51–52] P <0.001). Besides, age groups not affected by vaccination (<1 year, 5–9 years, and 10–14 years) presented minor but significant reductions (–49.1% [95% CI 44.5–53.4] P < 0.001; –23% [IC95% 22.4–23.6] P <0.001, and –17% [IC95% 16.4-19] P <0.001, respectively).ConclusionThree years after the implementation of VZV vaccination strategy, a significant incidence rates reduction is recorded, especially in children <5 years old, despite suboptimal coverage. Improving vaccination coverage will likely reflect a greater impact on the burden of disease.Disclosures All authors: No reported disclosures.

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