Effectiveness of BNT162b2 vaccine against the B.1.1.7 variant of SARS-CoV-2 among healthcare workers in Brescia, Italy.

Objectives The aim of the study was to evaluate the effectiveness of BNT162b2 vaccine (Pfizer®) among healthcare workers (HCWs) while a recrudescence of pandemics was hitting the Brescia county, with a high rate of the B.1.1.7 variant. Methods The study was performed in the context of the mandatory health surveillance at the workplaces, in the period between 25th January 2021 and 26th March 2021, when 6904 HCWs (78% of workforce) gained full protection. HCWs were classified by having received the full vaccine schedule or not. The SARS-CoV-2 infection was diagnosed by conventional RT-PCR on rhino-pharyngeal swabs, followed by gene sequencing in positive vaccinated HCWs. Results We observed 84 SARS-CoV-2 infections among HCWs, most among unvaccinated HCWs. Gene sequencing was successful in 5 cases only, 4 B.1.1.7 and 1 B1.525 variants. In the same period, Lombardy registered 192.829 confirmed COVID-19 cases, 40.029 of which in Brescia county. The incidence rate of the B.1.1.7 variant rose from 70% to 97%. Conclusions Results confirm the protective effects of BNT162b2. The vaccine campaign was effective not only in reducing the appearance of symptoms but also in decreasing the incidence of infections among vaccinated HCWs. We observed a reduced infection rate also among the residual unvaccinated HCWs.