We are witnessing a unique situation of ‘Tridemic’ with increased hospitalizations for seasonal flu and Respiratory Syncytial Virus (RSV) infections along with ongoing COVID-19. This has provided scientists with an opportunity for an in-depth study of a long-known but not well-studied phenomenon called ‘Viral Interference,’ where one infection can interfere with another. Scientists are trying to get answers on what happens if more than one virus infects an individual simultaneously.
As of now, most of the knowledge about infections, their pathogenesis, and epidemiology are mostly based on one pathogen – one disease model, which is, in fact, way far from reality. The results are accumulating to suggest that host coinfections could lead to positive and negative interactions between viruses. There is evidence of positive interactions between parainfluenza viruses, which cause respiratory infections in infants and young children, and between metapneumovirus and RSV—which are quite common in young children. In contrast, negative interactions have been reported between influenza B and adenoviruses and between rhinoviruses and the influenza A virus. Infections with rhinoviruses, the most common culprit behind the common cold, have also been found to block flu infections.