Researchers from the University of Missouri School of Medicine have discovered that children who had received a seasonal flu shot were less likely to suffer symptoms from a COVID-19 infection. The study reviewed records of 905 pediatric patients diagnosed with COVID-19. It was discovered that children who received the influenza vaccine in the current flu season had lower odds of experiencing symptoms, respiratory problems, or severe disease.
The researchers also found that children with COVID-19 who received the pneumococcal vaccine also had lower odds of experiencing an asymptomatic disease. It is known that e growth of one virus can be inhibited by a previous viral infection. 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.
Ref link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7789051/