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After the immunization of more than 20 thousand employees, the number of symptomatic cases of COVID-19 in the largest hospital complex in Latin America did not follow the growth trend observed in the city of SP

A study carried out by the Hospital das Clínicas da Faculdade de Medicina da USP  showed an efficiency of 50.7% after two weeks and 73.8% after five weeks since the complete vaccination with the Butantan immunizer against the new coronavirus. There were more than 20 thousand professionals from the complex vaccinated.

The research took into account the symptomatic cases of employees observed compared to the curve observed in the municipality of São Paulo during the same period.

It was possible to observe that the number of cases registered in the HC after vaccination did not follow the disease’s trend of exponential growth observed in the city of São Paulo. In 2020, before there was a vaccine available, the occurrences of COVID-19 maintained the same pattern both in HC and in the city of São Paulo.

In the third week of January, when vaccination started in HC, the city of São Paulo registered 16,200 new cases of COVID-19, while in the complex there were 51. In the last week of March, 23,900 cases were registered in São Paulo, against 46 in HC FMUSP.

If the growth trend of cases in the municipality were the same in the complex, the expectation in the HC would be greater than 175 occurrences of COVID-19 in the last week of March, but, with vaccination, the observed number was 73.8% lower.

The vaccination efforts in the HC complex, which brings together eight institutes, were carried out on January 18 and 21 for the first dose, and on February 14 and 16, for the second.

“In this study, we talk about vaccine effectiveness because it is an application in real life, different from what is done in clinical trials, which evaluate the effectiveness under specific conditions and considered ideal. This study in the cohort of HC employees, who vaccinated a large number of people, is essential because it corroborates the results obtained in the clinical studies of Butantan”, says the head of the HCFMUSP Infectious and Parasitic Diseases Division, Anna Sara Levin.

The study also assessed the occurrence of those considered to be variants of concern by the World Health Organization (WHO). Among 142 samples analyzed at random, 67 were identified as variants, of which 57 were from Amazonas (P1), 5 from the United Kingdom (B.1.1.7) and another 5 could not be identified by the methods used in the study.


Representation of the number of weekly Covid-19 cases in the city of São Paulo (SP) and among HCFMUSP health professionals. The arrows mark the administration of the 2 doses of CoronaVac in the hospital