ArticleVaccine2021
Does BCG provide long-term protection against SARS-CoV-2 infection? A case-control study in Quebec, Canada.
Article in Vaccine, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 14 papers.
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Who cites it
14 citing papers in PubMed, 16 citations in OpenAlex.
- Multiple BCG vaccinations for the prevention of COVID-19 and other infectious diseases in type 1 diabetes.Cell reports. Medicine · 2022Trial
- 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
- BCG immunization mitigates SARS-CoV-2 replication in macaques via monocyte efferocytosis and neutrophil recruitment in lungs.JCI insight · 2025Article
- Previous BCG vaccination is associated with less severe clinical progression of COVID-19.BMC medicine · 2023Article
- Review
- Efficacy of BCG Vaccination against COVID-19: Systematic Review and Meta-Analysis of Randomized Controlled Trials.Journal of clinical medicine · 2023Review
- BCG Vaccination: A potential tool against COVID-19 and COVID-19-like Black Swan incidents.International immunopharmacology · 2022Review
- Childhood Bacille Calmette-Guérin vaccination seems to selectively protect adult males from COVID-19 infection.Allergy · 2022Article
- BCG vaccination provides protection against IAV but not SARS-CoV-2.Cell reports · 2022Article
- Intravenous administration of BCG protects mice against lethal SARS-CoV-2 challenge.The Journal of experimental medicine · 2022Article
- Why Does the Severity of COVID-19 Differ With Age?: Understanding the Mechanisms Underlying the Age Gradient in Outcome Following SARS-CoV-2 Infection.The Pediatric infectious disease journal · 2022Review
- Article
- Off-target effects of bacillus Calmette-Guérin vaccination on immune responses to SARS-CoV-2: implications for protection against severe COVID-19.Clinical & translational immunology · 2022Article
- 100 years of the Bacillus Calmette-Guérin vaccine.Vaccine · 2021Article
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Authors and funding
10 authors at 4 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundEarly in the coronavirus disease 2019 (COVID-19) pandemic, before severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines became available, it was hypothesized that BCG (Bacillus Calmette-Guérin), which stimulates innate immunity, could provide protection against SARS-CoV-2. Numerous ecological studies, plagued by methodological deficiencies, revealed a country-level association between BCG use and lower COVID-19 incidence and mortality. We aimed to determine whether BCG administered in early life decreased the risk of SARS-CoV-2 infection in adulthood and the severity of COVID-19.
methodsThis case-control study was conducted in Quebec, Canada. Cases were patients with a positive SARS-CoV-2 nucleic acid amplification test performed at two hospitals between March-October 2020. Controls were identified among patients with non-COVID-19 samples processed by the same microbiology laboratories during the same period. Enrolment was limited to individuals born in Quebec between 1956 and 1976, whose vaccine status was accessible in a computerized registry of 4.2 million BCG vaccinations.
resultsWe recruited 920 cases and 2123 controls. Fifty-four percent of cases (n = 424) and 53% of controls (n = 1127) had received BCG during childhood (OR: 1.03; 95% CI: 0.89-1.21), while 12% of cases (n = 114) and 11% of controls (n = 235) had received two or more BCG doses (OR: 1.14; 95% CI: 0.88-1.46). After adjusting for age, sex, material deprivation, recruiting hospital and occupation there was no evidence of protection conferred by BCG against SARS-CoV-2 (AOR: 1.01; 95% CI: 0.84-1.21). Among cases, 77 (8.4%) needed hospitalization and 18 (2.0%) died. The vaccinated were as likely as the unvaccinated to require hospitalization (AOR: 1.01, 95% CI: 0.62-1.67) or to die (AOR: 0.85, 95% CI: 0.32-2.39).
conclusionsBCG does not provide long-term protection against symptomatic COVID-19 or severe forms of the disease.
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