OPV as Potential Protection Against COVID-19

Since the 1960s, studies have shown that oral polio vaccine (OPV) may have beneficialnon-specific effects, reducing morbidity and mortality from other infections than polio.Such beneficial non-specific effect have been observed for other live vaccines, includingmeasles, smallpox and BCG vaccine. For BCG, the vaccine for which the mechanism has beenstudied the most, the effects appear to be mediated through the innate immune system. TheCOVID-19 pandemic caused by the novel coronavirus SARS-CoV-2 has now caused over 7.1million cases and >400,000 deaths worldwide. As everywhere else, it is anticipated thatin Africa the older part of the population will be at risk of severe COVID-19. OPV iswidely used in Africa, but for children. Both polio and coronavirus are positive-strandRNA viruses, therefore it is likely that they may induce and be affected by common innateimmune mechanisms.In a randomised trial at the Bandim Health Project in Guinea-Bissau, the investigatorswill assess the effect of providing OPV vs no vaccine to 3400 persons above 50 years ofage. The trial will have the power to test the hypothesis that OPV reduces the combinedrisk of morbidity admission or death (composite outcome) by at least 28% over thesubsequent 6 months.