key: cord-0775210-byyzw1wg authors: Sansone, E.; Tiraboschi, M.; Sala, E.; Albini, E.; Lombardo, M.; Castelli, F.; De Palma, G. title: Effectiveness of BNT162b2 vaccine against the B.1.1.7 variant of SARS-CoV-2 among healthcare workers in Brescia, Italy date: 2021-05-07 journal: J Infect DOI: 10.1016/j.jinf.2021.04.038 sha: f5abfaf66374299bb51b3946baea53cbdc191fbb doc_id: 775210 cord_uid: byyzw1wg 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.  On 27th December 2020 the vaccine campaign against SARS-CoV-2 started in Europe and healthcare workers were the first target population group.  The vaccine campaign among healthcare workers was effective in decreasing the incidence of infections.  There was a reduced infection rate also among the residual unvaccinated healthcare workers. Such evidence could be explained by a sort of herd immunity gained in this population.  In addition the vaccine had a protective role in reducing the appearance of symptoms. 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. 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. 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. Coronavirus; COVID-19; vaccine; herd immunity. On 27 th December 2020 the vaccine campaign against SARS-CoV-2 started in Europe. Because of the high risk and their crucial role in tackling SARS-CoV-2 pandemic, healthcare workers (HCWs) were the first target population group. At the tertiary hospital "ASST Spedali Civili" of Brescia, Italy, a main European COVID-19 hospital, HCWs were vaccinated with a two-dose (21-day interval) schedule of BNT162b2 vaccine (Pfizer®), which had shown an efficacy of 95% in the prevention of COVID-19 (1). Encouraging data have been recently highlighted by reports dealing with in-mass vaccination campaign on HCWs in Israel and USA (2) (3) (4) . The present study was performed with the main aim of evaluating the effectiveness of BNT162b2 among HCWs while a recrudescence of pandemics was hitting the Brescia county, with a high rate of the B.1.1.7 variant. The study was performed in the context of the mandatory health surveillance at the workplaces. The analysis covers the period between 25 th January 2021 (when the first vaccinated workers theoretically gained the full protection, i.e. after at least 7 days from the second dose) and 13 th April 2021, when 6904 HCWs (78% of workforce) had gained the full protection. We monitored the SARS-CoV-2 infection and COVID-19 symptoms among HCWs 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. The cumulative incidence of infections in the period were normalized by 10.000 people, to allow comparison between HCWs and general population (Brescia county). Figure 1 shows the cumulative daily standardized (x 10 -4 people) incidence of SARS-CoV-2 infections among not vaccinated and vaccinated HCWs and in the general population. At the end of the observation period, vaccinated HCWs were at lower infection risk as compared to unvaccinated HCWs (by 2.6-folds), and even to a greater extent (6.2 folds) if compared to the general population. Interestingly, in the last weeks, the infection trends between HCWs reached a plateau, before among vaccinated then among non-vaccinated, whereas in the general population the infections were still raising. In the observation period, we observed 92 SARS-CoV-2 infections among HCWs, most among unvaccinated HCWs, the vaccine showing a significant protective effect against symptom development (Table 1) Obtained results confirm the protective effects of BNT162b2 (1) (2) (3) (4) . Noteworthy, results were observed while a recrudescent wave of the SARS-CoV-2 pandemic hit Lombardy and particularly the Brescia county, where the B.1.1.7 variant was highly prevalent. Obtained data show that 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. Such evidence could be explained by a sort of herd immunity, possibly resulting by a positive interaction between in-mass vaccination and the complex of protective measures operating in the hospital. The high rate of unsuccessful gene sequencing observed among infected vaccinated workers could be explained by a low viral burden, possibly related to a lower risk of SARS-CoV-2 transmission. Transition to endemicity of SARS-CoV-2 is thought to be the most probable epilogue to this pandemic (6) . We believe that a state of mild disease endemicity will be possible through extensive vaccinations campaign. Vaccination for COVID-19 should be made mandatory in all occupational contexts in which a high infective risk is present. Date -Fully protected workers, N. Non vaccinated Brescia Effectiveness of BNT162b2 vaccine against the B.1.1.7 variant of SARS-CoV-2 among healthcare workers in Unit of Occupational Health, Hygiene, Toxicology and Prevention Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine BNT162b2 mRNA Covid-19 Vaccine Effectiveness among Health Care Workers Early Evidence of the Effect of SARS-CoV-2 Vaccine at One Medical Center SARS-CoV-2 Infection after Vaccination in Health Care Workers in California ACKNOWLEDGEMENTS Not applicable. The authors declare that they have no competing interests. The authors declare no funding was required for the writing and submission of the manuscript. The authors were involved in the writing of the manuscript. All authors read and approved the final manuscript.