We tested whether providing BCG vaccine to healthcare workers (HCWs) could reduce non-planned absenteeism and thereby reduce the potential impact of the COVID-19 pandemic on healthcare systems in Africa. We conducted a multicenter, single-blinded, placebo-controlled randomized trial in Guinea-Bissau and Mozambique between December 2020 and June 2022. Participants were randomized 1:1 to BCG vaccine or placebo (saline) and followed by biweekly telephone calls for 6mo. The incidence of unplanned absenteeism due to illness was analyzed using Bayesian negative binomial regression yielding relative RRs. Secondary outcomes included infectious disease episodes, COVID-19 infection and all-cause hospitalizations. We enrolled 668 HCWs (Guinea-Bissau, n=503; Mozambique, n=165). The RR for absenteeism of BCG vs placebo was 1.29 (0.81 to 1.94) with comparable effects by country. No protection against infectious disease episodes (HR=1.18 [0.97 to 1.45]) or COVID-19 infection (HR=1.19 [0.80 to 1.75]) was observed. Two trial deaths (1 BCG, 1 control) were registered and nine admissions (3 BCG, 6 control), the all-cause admission HR being 0.51 (0.13 to 2.03). With 64% of the planned sample size and unplanned absenteeism rates lower than expected, BCG did not reduce self-reported absenteeism due to illness. Rather, BCG tended to increase the risk of self-reported absenteeism, infectious disease episodes and COVID-19 infections. This was a randomized control trial assessing non-specific effects of BCG vaccination in healthcare workers. There was no beneficial effect on self-reported absenteeism due to illness within 6mo of follow-up during the COVID-19 pandemic, but a trend towards fewer all-cause hospital admissions.
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