One thing that influenza and RSV infections have in common is the epidemic waves that occur each year during the cold season. In both cases, the pathogens are respiratory-transmissible RNA viruses. Although there are some similarities in pathogenesis and course of the disease, there are some fundamental differences between the two infectious diseases.
A large genetic variation is common to RNA viruses. This also applies to influenza viruses and respiratory syncytial virus (RSV). Eight RNA molecules in influenza viruses and one strand of RNA in RSV contain genetic information. There are 3 human-pathogenic species of influenza viruses: influenza A, the H1N1 and H3N2 subtypes most important in humans, and influenza B, the Victoria strain and the Yamagata strain. Six genetic lineages are known from the influenza C virus, which causes only mild disease. The two RSV subtypes RSV A (14 genotypes) and RSV B (24 genotypes) are similarly diverse. For all subtypes, genotypes, and lines, there are different strains that are subject to antigenic drift and are therefore constantly changing.
What influenza and RS viruses have in common is the immunogenicity of surface proteins through which the viruses attach to host cells. That is, these proteins are the attack points of our immune system. The fact that the two respiratory viruses are transmitted through droplet infection during coughing and sneezing is only part of the truth: “Almost 50% of influenza and RSV transmissions occur through smear infections,” asserts Priv.-Doz. Dr. Monika Redlberger-Fritz, Center for Virology, Medical University of Vienna.