Severity of RSV Infections in Twins

Respiratory syncytial virus (RSV) infection is the most common cause of severe lower respiratory tract infection (LRTI) in the pediatric population worldwide. Age at the time of infection, prematurity, multiparity, exposure to smoke and the level of passive immunity transmitted at birth are the main risk factors for lower respiratory infection associated with RSV. Other factors, including the innate immune response, respiratory microbiota, and intra-host viral heterogeneity, may also affect outcomes but are not fully considered in RSV infection. Exploring the impact of these factors is difficult due to the heterogeneity of the population which makes statistical adjustment difficult. Thus, twin models are useful in understanding the impact of the host on the environment, as twins often share similar exposure to infection and many risk factors, but not all are ie different prenatal and postnatal conditions, differential transfer of maternal antibodies and the genetic makeup of heterozygotes.