Bacillus Calmette-Guérin vaccine to reduce healthcare worker absenteeism in COVID-19 pandemic, a randomized controlled trial

Clin Microbiol Infect. 2022 Sep;28(9):1278-1285. doi: 10.1016/j.cmi.2022.04.009. Epub 2022 Apr 28.


Objectives: The COVID-19 pandemic increases healthcare worker (HCW) absenteeism. The bacillus Calmette-Guérin (BCG) vaccine may provide non-specific protection against respiratory infections through enhancement of trained immunity. We investigated the impact of BCG vaccination on HCW absenteeism during the COVID-19 pandemic.

Methods: HCWs exposed to COVID-19 patients in nine Dutch hospitals were randomized to BCG vaccine or placebo in a 1:1 ratio, and followed for one year using a mobile phone application. The primary endpoint was the self-reported number of days of unplanned absenteeism for any reason. Secondary endpoints included documented COVID-19, acute respiratory symptoms or fever. This was an investigator-funded study, registered at (NCT03987919).

Results: In March/April 2020, 1511 HCWs were enrolled. The median duration of follow-up was 357 person-days (interquartile range [IQR], 351 to 361). Unplanned absenteeism for any reason was observed in 2.8% of planned working days in the BCG group and 2.7% in the placebo group (adjusted relative risk 0.94; 95% credible interval, 0.78-1.15). Cumulative incidences of documented COVID-19 were 14.2% in the BCG and 15.2% in the placebo group (adjusted hazard ratio (aHR) 0.94; 95% confidence interval (CI), 0.72-1.24). First episodes of self-reported acute respiratory symptoms or fever occurred in 490 (66.2%) and 443 (60.2%) participants, respectively (aHR: 1.13; 95% CI, 0.99-1.28). Thirty-one serious adverse events were reported (13 after BCG, 18 after placebo), none considered related to study medication.

Conclusions: During the COVID-19 pandemic, BCG-vaccination of HCW exposed to COVID-19 patients did not reduce unplanned absenteeism nor documented COVID-19.

Keywords: BCG; COVID-19; Health care workers; Randomized controlled trial; Trained immunity.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Absenteeism
  • BCG Vaccine
  • COVID-19* / epidemiology
  • COVID-19* / prevention & control
  • Health Personnel
  • Humans
  • Mycobacterium bovis*
  • Pandemics / prevention & control
  • SARS-CoV-2


  • BCG Vaccine

Associated data