Bastos, Leonardo S.

Izbicki, Meyer

Izbicki, Rafael

Lopes, Hedibert F.

Santos, Tiago Mendonça dos

English

Cadernos Espinosanos (E-Journal)

How many hospitalizations has the COVID-19 vacci-nation already prevented in São Paulo?Rafael Izbicki0000-0000-0000-0000 ,I,* Leonardo S. Bastos0000-0000-0000-0000 ,II Meyer Izbicki0000-0000-0000-0000 ,III Hedibert F. Lopes0000-0000-0000-0000 ,IV Tiago Mendonçados Santos0000-0000-0000-0000 IV,VIDepartamento de Estatistica, Universidade Federal de Sao Carlos, Sao Carlos, SP, BR. IIPrograma de Computacao Cientifica, Fundacao Oswaldo Cruz, Rio deJaneiro, RJ, BR. IIILaboratorio de Funcao Pulmonar, Divisao Respiratoria, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal deSao Paulo (UNIFESP - EPM), Sao Paulo, SP, BR. IV INSPER Instituto de Ensino e Pesquisa, Sao Paulo, SP, BR. VEstatikos - Assessoria e Consultoria Estatistica, SaoPaulo, SP, BR.Izbicki R, Bastos LS, Izbicki M, Lopes HF, Santos TM. How many hospitalizations has the COVID-19 vaccination already prevented in São Paulo? Clinics(Sao Paulo). 2021;76:e3250*Corresponding author. E-mail: rafaelizbicki@gmail.comThe high hospitalization rate of patients with coronavirusdisease (COVID-19) has led to the collapse of healthcaresystems in many countries. Vaccines for COVID-19 emerged inlate 2020, and they have been shown to be a powerful tool todecrease hospitalization numbers in countries that were able toquickly vaccinate a majority of their populations (1).The goal of this study was to estimate how many COVID-19-related hospitalizations were prevented in the state ofSão Paulo (Brazil) because of vaccines as of May 28, 2021.We used data from the SIVEP-Gripe database, which wascreated by the Brazilian Ministry of Health in 2019 to recorddeaths and hospitalized cases with severe acute respiratoryillness (SARI) (2). The SIVEP-Gripe dataset is open-accessand is updated weekly on the website: https://opendatasus.saude.gov.br/dataset. We used the 14-day rolling average ofthe daily number of patients hospitalized for SARI becauseof COVID-19 (SARI-COVID).Until May 28, 2021, only individuals aged 465 years1were vaccinated. Thus, we only modeled hospitalizationsthat were avoided in this particular group. We created acounterfactual model that used a linear regression to predictthe number of SARI-COVID hospitalizations in people aged465 years that was based on the number of hospitalizationsfor patients between ages 55 and 62 years (the rationale forthis choice is described below). The model was estimatedusing only data before the first vaccination, which occurredon February 8, 2021. The counterfactual curve was thenestimated by applying the fitted model to the period afterFebruary 8, 2021. Figure 1 shows the actual number ofhospitalizations in patients aged 465 years, as well as thecounterfactual curve with 95% prediction intervals (3) andfitted pre-vaccination model. The vertical lines indicate whenthe vaccination was initiated for different age groups.Figure 1 shows that the counterfactual curve is alwayshigher than the observed data, indicating that hospitalizationlevels would have been much higher if these groups hadnot been vaccinated. The difference between these curvesbecame even larger in May of 2021. The reduction in hospi-talizations reached its maximum of 66.1% (95% confidenceinterval: 65.7%, 67.5%) on May 28, 2021. The effect of vacci-nations on the hospitalization rate of individuals aged465 years is likely to improve: the Ministry of Health ofBrazil has adopted a policy of using a 1-to 3-month intervalbetween doses depending on the vaccine; thus, manyindividuals have only received one dose so far.This counterfactual analysis has three main assumptions:1) Without vaccination, the relationship between the numberof hospitalizations in people aged 465 years and theyounger group would have been the same after February8, 2021.2) Vaccination had no substantial effect on the youngergroup before May 28, 2021.3) The linear model is a good approximation.While Assumption 1 cannot be verified, we defined theage range of the younger group such that Assumptions 2and 3 would approximately hold. Vaccination of individualsaged o62 years only started on May 6, 2021; thus, there wasnot enough time to observe its effect by May 28, 2021.Moreover, the blue curve in Figure 1 indicates that the linearmodel is a good approximation, possibly because the youngergroup was close in age to the group aged 465 years.Using the areas between the curves, we observed that app-roximately 24,364 hospitalizations were avoided in São Paulobecause of vaccination before May 28, 2021. Considering thatthe estimated mortality rate of hospitalized patients aged465 years with SARI-COVID-19 is approximately 45%,approximately 10.964 deaths might have been prevented byvaccination during this period. Moreover, using estimates of theaverage COVID-19 hospitalization costs2, US $297 million mayhave been saved, which is enough to purchase almost 30million additional doses of vaccine (at US $10 each).Copyright & 2021 CLINICS – This is an Open Access article distributed under theterms of the Creative Commons License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in anymedium or format, provided the original work is properly cited.No potential conflict of interest was reported.DOI: 10.6061/clinics/2021/e32501The COVID vaccination schedule of the state of São Paulo is locatedat https://vacinaja.sp.gov.br/ 2See https://papers.ssrn.com/sol3/papers.cfm?abstract_id=37380871COMMENTSIn conclusion, we provide evidence that vaccines are aneffective way to reduce mortality because of COVID-19, aswell as to save substantial financial resources during thepandemic.’ REFERENCES1. Haas EJ, Angulo FJ, McLaughlin JM, Anis E, Singer SR, Khan F, et al.Impact and effectiveness of mRNA BNT162b2 vaccine against SARS-CoV-2 infections and COVID-19 cases, hospitalizations, and deaths following anationwide vaccination campaign in Israel: an observational study usingnational surveillance data. Lancet. 2021;397(10287):1819-29. https://doi.org/10.1016/S0140-6736(21)00947-82. Bastos LS, Niquini RP, Lana RM, Villela DAM, Cruz OG, Coelho FC, et al.COVID-19 and hospitalizations for SARI in Brazil: a comparison up tothe 12th epidemiological week of 2020. Cad Saude Publica. 2020;36(4):e00070120. https://doi.org/10.1590/0102-311x000701203. Neter J, Kutner MH, Nachtsheim CJ, Wasserman W. Applied linearstatistical models. Chicago: Irwin; 1996.Figure 1 - Number of hospitalizations due to SARI-COVID in patients aged 465 years (dark green), fitted pre-vaccination model (blue),and estimated counterfactual curve for the setting without vaccines (red).2COVID-19 vaccination effect in São PauloIzbicki R et al.CLINICS 2021;76:e3250

How many hospitalizations has the COVID-19 vaccination already prevented in São Paulo?

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How many hospitalizations has the COVID-19 vaccination already prevented in São Paulo?

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