Risk of Infection and Duration of Protection after the Booster Dose of the Anti-SARS-CoV-2 Vaccine BNT162b2 among Healthcare Workers in a Large Teaching Hospital in Italy: Results of an Observational Study.

The efficacy of the first schedule of COVID-19 mRNA vaccines has decreased after the surge of the Delta variant, posing the need to administer a booster dose to enhance the neutralising immune response. This study aims at evaluating the duration of protection given by the booster dose of Pfizer-BioNTech BNT162b2 mRNA vaccine in healthcare workers (HCWs) of a large teaching hospital in Rome and to analyse the factors associated with post-booster vaccination infections. Data about vaccinations of HCWs with the BNT162b2 vaccine and nasal swabs positive for SARS-CoV-2 were extracted from the digital archives of the hospital from 27 September 2021 to 31 May 2022. In total, 5770 HCWs were observed. The cumulative risk of becoming infected by SARS-CoV-2 increased with time (2.5% at 4 weeks, 17% at 12 weeks and 40% at 24 weeks) and was significantly higher for females, younger classes of patients and for those who had developed a hybrid immunity (natural infection plus one dose, namely the primary schedule, added to the booster dose) compared to those who had completed the three doses. This study describes the duration and the determinants of the protection against infections after the booster dose of COVID-19 vaccine, highlighting the need for continuous monitoring of vaccine-induced immunogenicity.

Postmortem CT pulmonary findings in SARS-CoV-2-positive cases: correlation with lung histopathological findings and autopsy results.

INTRODUCTION/PURPOSE: Postmortem computed tomography (PMCT) is a valuable tool for analyzing the death of patients with SARS-CoV-2 infection. The purpose of this study was to investigate the correlation between PMCT lung findings in autopsy cadavers positive for SARS-CoV-2 infection and the severity of COVID-19 lung disease by histopathological analysis. MATERIALS AND METHODS: We reviewed chest PMCT findings, paying particular attention to the lung parenchyma, in 8 autopsy cases positive for SARS-CoV-2. Correlations between chest PMCT and histopathological findings were assessed. Clinical conditions and comorbidities were also recorded and discussed. The primary cause of death was finally considered. RESULTS: In 6/8 cases, pulmonary PMCT findings were massive consolidation (4/8) and bilateral diffuse mixed densities with a crazy-paving pattern (2/8). These cases showed severe pulmonary signs of COVID-19 at histopathological analysis. In the remaining 2/8 cases, pulmonary PMCT findings were scant antideclive ground-glass opacities in prevalent gradient densities attributed to hypostasis. In 4/8 cases with massive consolidations, important comorbidities were noted. In 6/8 cases with severe pulmonary histopathological signs of lung COVID-19, autopsy found that the cause of death was cardiorespiratory failure. In the remaining 2/8 cases, histopathological analysis revealed lung alterations due to edema and some signs of SARS-CoV-2 infection; the cause of death was not attributed to SARS-CoV-2 infection (Table 1). DISCUSSION AND CONCLUSION: Chest PMCT findings correlate with the severity of COVID-19 lung disease at histopathology examination. According to our results, there may also be a relationship between cause of death and PMCT findings in COVID-19, which must be critically analyzed considering clinical antemortem data.