Impact of Bacillus Calmette-Guerin (BCG) vaccination on postoperative mortality in patients with perioperative SARS-CoV-2 infection

During the COVID-19 pandemic, multiple theories were proposed based on the observation that countries with an ongoing national Bacillus Calmette-Guerin (BCG) immunization programme had lower SARS-CoV-2 case rates and COVID-19 mortality than countries that had stopped BCG vaccine administration. There was, however, no evidence supporting or disputing this theory. Owing to the uncertainty on the role of BCG vaccine on the outcomes of patients with perioperative SARS-CoV-2 infection, this international study aimed to determine whether previous BCG vaccination was associated with reduced postoperative pulmonary complications (PPC) and 30-day mortality in patients undergoing surgery who developed SARS-CoV-2 infection. According to these findings, prior BCG vaccination does not appear to protect SARS-CoV-2-infected patients against PPCs and 30-day mortality.