Severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection in asymptomatic vaccinated healthcare workers

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has caused >2.7 million deaths worldwide,1 devasting health systems end economies worldwide. Since the first months of the pandemic, a rapid and massive effort has been performed by the scientific community to develop a safe and effective vaccine against SARS-CoV-2.2 In Italy, the first population to receive the vaccine was healthcare workers (HCWs) who are principally exposed to SARS-CoV-2 infection during the management of coronavirus disease 2019 (COVID-19) patients.3 Several doubts remain concerning the neutralizing properties of antibodies produced after vaccination.4 Moreover, little is known about transient infections in vaccinated individuals who therefore could be potential carriers of the disease.5 Finally, it is important to understand the actual efficacy of the approved vaccines against SARS-CoV-2 variants, which have led to enhanced virus transmissibility, morbidity, and mortality.6,7 Here, we report several asymptomatic and vaccinated HCWs who tested positive for SARS-CoV-2 during surveillance testing. [...]all of the cases we observed in this report were due B.1.1.7 lineage infection. [...]although further data and observations of larger cohorts are needed, we strongly believe that continued attention should be devoted to the problem of infection in vaccinated people.