Reduction in COVID-19 prevalence in healthcare workers in a university hospital in southern Brazil after the start of vaccination.

Background: The quick spread of SARS-CoV-2 led to the development of vaccines that are capable of reducing infection and the number of more severe COVID-19 cases.

Objective: To assess COVID-19 prevalence among healthcare workers (HCWs) after vaccination against SARS-CoV-2.

Methods: This was a cross-sectional study on the prevalence of COVID-19 diagnosis among 7523 HCWs vaccinated against SARS-CoV-2 with CoronaVac and ChAdOx1 nCoV-19 in a university hospital, in southern Brazil, between January 18 and March 18, 2021.The variables evaluated were: sex, age, work area, role, source of infection, previous diagnosis of COVID-19, date of vaccine administration, type of vaccine, and need for hospitalization. The statistical analysis used Poisson regression and Fisher's exact test with SPSS software version 25, and a level of significance set at 5%.

Results: 813 vaccinated HCWs showed symptoms suggestive of COVID-19, of whom 35.4% (288) had a detectable result after undergoing RT-PCR for SARS-CoV-2. There was a reduction of 62% in new cases of COVID-19 among HCWs in the institution 7 weeks after the start of vaccine rollout.

Conclusions: Our data suggest that the vaccines used by the institution reduced the number of COVID-19 cases among healthcare workers, demonstrating the effectiveness of the vaccines.