The Science magazine published an article by Chumakov et al. (2020) titled “Can existing live vaccines prevent COVID-19?” (science.sciencemag.org). The vaccine the article referred to is OPV (oral polio vaccine). OPV immunization induces long-lasting antibody response toward poliovirus. With time, several experiments revealed that OPV has some positive side effects, protecting children from diseases caused by other viruses and bacteria. The study showed that repeated OPV immunization, in the absence of circulating poliovirus, reduced all-cause child mortality at the range of 16-19%. This means OPV can prevent diseases from unrelated pathogens (pathogens other than polio). Another study showed that OPV reduced influenza-related morbidity by 3.8-fold on average. Based on the mounting evidence, experts then concluded that OPV induces not only adaptive immune response (antibody and T cell) which is specific and long-lasting for polio but also “trains” the earlier level of the immune response, called ‘innate immunity’. The innate immunity, which confers broad protection from the unrelated pathogen, however, is short term. OPV given during childhood will not confer protection to unrelated pathogens during adulthood unless a booster is provided. This ‘temporary nature’ of the innate immune response is not unique to OPV, but common to all live attenuated vaccines such as BCG, measles and small-pox. The article in Jakarta Post argues that Indonesia, as a country where OPV is still used for mass immunization, should conduct a clinical trial to test the efficacy of OPV to prevent COVID- 19. If proven to be effective, OPV can be administered as an innovative stop-gap measure, until a vaccine specific for SARS-CoV-2 is available.
