DOM COVID-19 Journal Club: SARS-CoV-2 rates in BCG-vaccinated and unvaccinated young adults confirmed cases of coronavirus disease

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Study objectives: Research letter to determine if the Bacillus Calmette–Guérin (BCG) vaccine administered in childhood for tuberculosis reduces the rate of COVID-19 infections.

Methods and Results: The BCG vaccine was routinely administered to all newborns in Israel between 1955 and 1982 with high acceptability and coverage amongst citizens. Since 1982, the vaccine has only been administered to immigrants from countries with high TB rates (less than 5% of the population of Israel). The authors compared rates of SARS-CoV-2 infection (symptoms and positive RT-PCR test) between those born during the vaccination period (1979-81) and following the cessation of country-wide vaccination (1983-85). Cases were included in the analysis if they occurred between 3/1/2020 and 4/5/2020. χ2 tests were used to assess statistical significance between groups.

72,060 test results were reviewed. 3,064 of these were from patients born between 1979 and 1981 (cohort 1) with 2,869 born between 1983 and ’85 (cohort 2). Cohort 1 was 49.2% male with an average age of 40 years while cohort 2 was 50.8% male and had an average age of 35 years. There were no statistical differences in the proportion of tests positive for SARS-CoV-2 between cohort 1 (vaccinated) and cohort 2 (unvaccinated), p=0.09. There were also very few cases of severe illness in either cohort (1 case requiring mechanical ventilation or ICU admission in each group).

Limitations: The authors included those born outside Israel who may have been vaccinated despite being included in the unvaccinated group, though the authors estimate this is less than 5% of the population.

Main conclusions: The BCG vaccine does not have a protective effect against COVID-19 infection in early adulthood.

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The Department of Medicine COVID-19 Journal Club is dedicated to understanding and applying data on COVID-19 to inform prevention and management efforts for healthcare workers and patients

This article by Ashley Kates, PhD, postdoctoral trainee, Infectious Disease. Reviewed by Nasia Safdar, MD, PhD, professor, Infectious Disease, vice chair for research, Department of Medicine.

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