Sars-CoV2 infection, before and after vaccination, in health care workers of a medium and high complexity hospital.

Abstract

Introduction: The COVID-19 pandemic highlighted the importance of essential health care workers.

Objective: To estimate the occurrence of Sars_CoV2 virus infection in hospital staff before and after implementation of the institutional vaccination program and the preventive fraction attributable to vaccination.

Material and methods: Historical cohort study, having as starting point the date of the first employee diagnosed with Covid19 in the Hospital. About one thousand workers were examined, during the study period from June 2020 to October 2021. The Kaplan-Meier statistic was used to compare the infection, rate and the preventive fraction attributable to the vaccination program.

Results: There were statistically significant differences in the reduction of cases according to type of work, with the assistential workers experiencing a reduction of 58.1%, from 124 to 52 and the difference in median infection rate, before and after, Log Rank = 127.4 gl = 1 p = 0.000; the administrative 51.7% from 29 to 14, median Log Rank = 34.4 gl = 1 p = 0.000, and the operatives 45.5% from 11 to 6, median Log Rank = 13.5 gl = 1 p = 0.000. The preventive attributable fraction among assistants was 47.5% (37.4-54.9); 85.2% (77.7-88.9) in administrative and a non-significant reduction of 43.6% (-20.7, 63.2) in operatives. Conclusions: Healthcare workers are at high risk of contracting Sars_CoV2 infection. It was a wise decision to vaccinate all hospital workers, the impact is demonstrable.