Flu Vaccine Decreases COVID-19 Symptoms in Children by Colleen Fleiss on February 6, 2021 at 6:32 AM Children who received a seasonal flu shot are less likely to suffer symptoms from a COVID-19 infection, said University of Missouri School of Medicine researchers. The finding comes from a review of more than 900 children diagnosed with COVID-19 in 2020. "It is known that the growth of one virus can be inhibited by a previous viral infection," said Anjali Patwardhan, MD, professor of pediatric rheumatology and child health. "This phenomenon is called virus interference, and it can occur even when the first virus invader is an inactivated virus, such as the case with the flu vaccine."