In a randomized, double-blinded, placebo-controlled phase 2/3 trial, Faustman et al.
investigate the safety and efficacy of multiple doses of the more than 100-year-old
Bacillus Calmette-Guérin (BCG) vaccine against COVID-19. They also determine vaccine
efficacy against other infectious diseases, which, if present, would suggest platform
protection against new SARS-CoV-2 variants.