BCG Vaccination to Prevent COVID-19

The current COVID-19 epidemic threatens to overwhelm the capacity of many countries to meet their populations' health care needs. Although several vaccines specific for SARS-CoV-2 have been or are being developed, these require testing in animal and human safety studies and they are unlikely to be available during the expected peak periods of the growing epidemic. Two groups at especially high risk of infection and disease are front line health care workers working directly with COVID-19 patients and elderly residents of group homes or facilities that provide skilled nursing care to this frail population. Interim measures to protect these groups while we await a high efficacy vaccine are desperately needed. Based on the capacity of BCG to (1) reduce the incidence of respiratory tract infections in children and adults; (2) exert antiviral effects in experimental models; and (3) reduce viremia in an experimental human model of viral infection, we hypothesize that BCG vaccination may induce (partial) protection against susceptibility to and/or severity of SARS-CoV-2 infection. This study will evaluate the efficacy of BCG to reduce risk of infection by SARS-CoV-2 and mitigate COVID-19 disease severity in at risk health care providers. A phase III randomized controlled trial provides the highest validity to answer this research question. Given the immediate threat of the SARS-CoV-2 epidemic the trial has been designed as a pragmatic study with a highly feasible primary endpoint, which can be continuously measured. This allows for the most rapid identification of a beneficial outcome that would allow other at-risk individuals, including the control population, to also benefit from the intervention if and as soon as it has demonstrated efficacy and safety.