Evaluating the effect of BCG vaccination for non-specific protection from infection in senior citizens during the COVID-19 pandemic: a randomised clinical trial.

The Bacillus Calmette-Guérin (BCG) vaccine may induce non-specific protection against unrelated infections. We tested the effect of BCG on the risk of infections among Danish senior citizens. Single-blinded randomised controlled trial including 1,676 volunteers >65 years. Participants were randomised 1:1 to BCG or placebo and followed for 12 months. The primary outcome was acute infection leading to medical contact. Secondary outcomes were verified SARS-CoV-2 infection, self-reported respiratory symptoms, and all-cause hospitalisation. Data was analysed using Cox regression models, estimating hazard ratios (HR) with 95% confidence intervals (CI). The incidence of acute infection was 52.1 and 58.2 per 100 person-years for BCG and placebo respectively (HR=0.89, 95% CI=0.78-1.02). There was no effect of BCG on SARS-CoV-2 infections (0.97, 0.75-1.26) or all-cause hospitalisations (1.10, 0.80-1.50), but BCG was associated with more respiratory symptoms (1.21, 1.10-1.33). BCG reduced the incidence of acute infections among participants <75 years (0.82, 0.70-0.95) but not among those >75 years (1.14, 0.88-1.47). In participants, who were COVID-19 vaccinated before enrolment, BCG was associated with lower incidence of acute infections (0.65, 0.50-0.85). BCG did not reduce risk of acute infections among Danish seniors overall, but the effect was modified by age group and COVID-19 vaccination. ClinicalTrials.gov (NCT04542330) and EU Clinical Trials Register (EudraCT number 2020-003904-15). In a randomised clinical trial among Danish senior citizens, BCG vaccination did not reduce the overall risk of acute infection, but BCG was associated with reduced risk in participants <75 years and participants who received COVID-19 vaccines prior to enrolment.

Informations de copyright

Copyright © 2024. Published by Elsevier Ltd.

Déclaration de conflit d'intérêts

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.