BCG vaccine safety in COVID-19 convalescent adults: BATTLE a randomized controlled trial

INTRODUCTION: The safety of BCG revaccination is uncertain and there is no data on its use in patients with COVID-19. METHODS: COVID-19 convalescent adults confirmed by SARS-CoV-2 RT-PCR in South-America were 1:1 randomized in the first 14 days of symptoms to BCG intradermal vaccine or placebo and evaluated for adverse events on days 7, 14, 21, and beyond 40 days. Clinical Trial Registration: NCT04369794. RESULTS: 151 placebo and 148 BCG patients were included in the final analysis, with an average age of 40.7 years. No severe adverse event to BCG was reported. On day 7, 130 (87.8%) of the BCG recipients had local reaction, average size of 10.6 ± 6.4 mm, compared to only 2 (1.3%) placebos. Lesions gradually shrunk in size (mean 10.5 mm, 9.7 mm, and 6.8 mm at 14, 21, and beyond 40 days, respectively. The number of symptoms in any of the visits was not different between groups, and anosmia resolved earlier (25.7% vs. 37.1% at 7 days, OR = 1.70, 1.01–2.89, p = 0.035) in the BCG recipients. CONCLUSION: The BCG revaccination is safe in convalescent COVID-19 adults of a tuberculosis endemic region, regardless of tuberculin or IGRA test results. Local adverse events were similar though occurred earlier to that previously reported in children.