A retrospective observational study was conducted among healthcare
workers (HCWs) in a tertiary paediatric hospital. The study covered the
period before and after implementation of the vaccination programme and
evaluated the incidence of new SARS-CoV-2 infections in both periods.
Risk factors of the new SARS-CoV-2 infection and COVID-19 vaccine
effectiveness was also assessed in a real-world setting. The overall
incidence of SARS-CoV-2 infections among HCWs in the study period was
19.4% with a high proportion of asymptomatic individuals (45.1%). The
incidence before vaccination was 16.6% and nurses had a higher risk of
infection, while physicians had a reduced risk (OR 1.80, 95% CI
1.29–2.52; and OR 0.45, 95% CI 0.30–0.68). Within two months of
implementation, the programme achieved a high (88.9%) vaccination
coverage in our cohort, although some disparities in vaccination rates
were observed. In particular, older individuals, physicians, those
working in clinical settings, and those previously uninfected were more
likely to be vaccinated. The overall incidence of SARS-CoV-2 infection
after vaccination deployment was 6.3% (40.0% in unvaccinated
individuals and 3.2% in individuals vaccinated with at least one dose).
The estimated vaccine efficacy was high (95.0%) in fully vaccinated
HCWs and similar to those observed previously in clinical trials and
real-world settings.