ArticleBMC medicine2023
Previous BCG vaccination is associated with less severe clinical progression of COVID-19.
Article in BMC medicine, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
5 citing papers in PubMed.
- Bacillus Calmette-Guérin Vaccination and SARS-CoV-2 Infection among Healthcare Workers: A Case-Control Study in Cape Verde.Portuguese journal of public health · 2026Article
- Trained immunity modulators: A new frontier in immunoregulation and disease intervention.Journal of advanced research · 2026Review
- Association between COVID-19 and the incidence of type 1 diabetes in Portugal - a registry study.BMC endocrine disorders · 2024Article
- BCG-mediated viral protection goes biphasic.Nature immunology · 2024Article
- Overdosage of PPD immunotherapy causing tuberculosis-like skin lesionsAnais brasileiros de dermatologiaArticle
Corrections and comments
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Authors and funding
24 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundBCG vaccination, originally used to prevent tuberculosis, is known to "train" the immune system to improve defence against viral respiratory infections. We investigated whether a previous BCG vaccination is associated with less severe clinical progression of COVID-19
methodsA case-control study comparing the proportion with a BCG vaccine scar (indicating previous vaccination) in cases and controls presenting with COVID-19 to health units in Brazil. Cases were subjects with severe COVID-19 (O2 saturation < 90%, severe respiratory effort, severe pneumonia, severe acute respiratory syndrome, sepsis, and septic shock). Controls had COVID-19 not meeting the definition of "severe" above. Unconditional regression was used to estimate vaccine protection against clinical progression to severe disease, with strict control for age, comorbidity, sex, educational level, race/colour, and municipality. Internal matching and conditional regression were used for sensitivity analysis.
resultsBCG was associated with high protection against COVID-19 clinical progression, over 87% (95% CI 74-93%) in subjects aged 60 or less and 35% (95% CI - 44-71%) in older subjects.
conclusionsThis protection may be relevant for public health in settings where COVID-19 vaccine coverage is still low and may have implications for research to identify vaccine candidates for COVID-19 that are broadly protective against mortality from future variants. Further research into the immunomodulatory effects of BCG may inform COVID-19 therapeutic research.
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