Commentary: Trained immunity and beyond: the not-yet lost chance to win with COVID-19

COVID-19 pandemic has frightened people and governments all around the world. The common opinion is that there are no efficient preventive measures but masks, isolation, and social distancing. The deliverance is hoped from the SARS-CoV-2-specific vaccine, which must be efficient and cheap. But, so far nobody knows when, and if such a vaccine will be developed and mass-produced. Trained immunity with oral polio vaccine (OPV) was recently proposed as a temporal solution against the heavy course of COVID-19. However, politics do not seem to follow, and the scientific world should react because humanity has no time to lose. Below, we support this with our thoughts.