Impact of the Covid-19 Vaccination Campaigns in Argentina During 2021: An Observational Quantification of the Death Probability for Confirmed Cases in Buenos Aires Province

Background: A COVID-19 vaccination campaign was launched in Argentina in January 2021. The vaccines then available were administered to the population in several different schemes. This observational study presents a quantification of the impact of the different schemes on the probability of death for confirmed COVID-19 cases in Argentina’s Buenos Aires Province. The results provide a local measure of the schemes’ effectiveness that heretofore has been lacking.Methods: The study’s main source of information is the Integrated Health Information System database, which contains 1,538,113 records of confirmed COVID-19 cases reported in 2021 in the Province. After applying exclusion criteria, 1,445,874 records (94%) remained. To assess the real-world effectiveness of the vaccination campaign, two categorical variables representing vaccination status were defined. Probability of death was formulated as a generalized linear model with a logistic link and includes variables for geography, a socio-economic level index, symptom onset, sex, and vaccination status as well as interactions between certain of them. The effectiveness level was derived from the death probability estimates.Findings: The study’s results showed that the most effective vaccine was rAd26-rAd5 (Sputnik), followed by ChAdOx1-S (AZ/Covishields) and then BBIBP-CorV (Sinopharm), both for one dose and two or more. Effectiveness levels were always below 50% for a single dose and ranged from 50% to 90% for two or more. Particularly interesting findings were revealed by the variables for infected persons’ municipality of residence and time of year of symptom onset. A municipality's socioeconomic level proved to be a moderately good predictor of death probability, which was slightly higher in municipalities with poorer populations. Also, death probability was found to rise in the winter season. Interpretation: The vaccination campaigns conducted in 2021 in Buenos Aires Province had a positive impact on its population in preventing COVID-19 deaths. However, the level of impact depended heavily on each individual’s characteristics.Funding: Partial funding for the study was provided by the project entitled “Development and Implementation of Computational, Statistical and Data Science Tools for the Evaluation of Public Policies relating to the SARS-CoV-2 Pandemic” (PIDAE-UBA, 2022), and by the Industrial Engineering Department, FCFM, University of Chile. The first author was partially funded by the Instituto Sistemas Complejos de Ingeniería (ISCI, Chile, ANID PIA/PUENTE AFB22003) and by subsidies granted under UBACyT 20020170100495BA (Argentina) and PIP-CONICET 11220200100084CO (Argentina).Declaration of Interest: We declare no competing interests.