BCG Vaccine for Covid-19 in Health Care Workers

Evaluation of BCG-Denmark vaccine's effect on Covid-19 risk among healthcare workers

Study design

International, double-blind, placebo-controlled trial


  • Number of patients studied: 3988 (modified intention-to-treat population: 1703 in BCG group, 1683 in placebo group)
  • Inclusion criteria: Health care workers
  • Exclusion criteria: Participants with a positive test for SARS-CoV-2 at baseline


  • Experimental group: BCG-Denmark vaccine
  • Control group: Saline placebo

Primary outcome: Symptomatic Covid-19 and severe Covid-19 by 6 months

Secondary outcomes

Hazard ratio for any Covid-19 episode: 1.23 (95% CI, 0.96 to 1.59)

Safety outcomes

Adverse EventsBCG GroupPlacebo Group

Potential issues and biases

1. Inability to recruit the planned sample size
2. Reduced participant observation time
3. Trial definition of severe Covid-19 differed from widely used definitions
4. Definition of symptomatic Covid-19 limited to the original case definition
5. Blinding challenges in BCG trials


Vaccination with BCG-Denmark did not result in a lower risk of Covid-19 among health care workers than placebo.

Pittet, L. F., Messina, N. L., Orsini, F., Moore, C. L., Abruzzo, V., Barry, S., ... Curtis, N. (2023). Randomized Trial of BCG Vaccine to Protect against Covid-19 in Health Care Workers. New England Journal of Medicine, 388(17), 1582-1596.