Transmission of Respiratory Syncytial Virus Infection Within Families Terho Heikkinen,1,3 Heikki Valkonen,1,3,a Matti Waris,2 and Olli Ruuskanen1,3 Departments of 1Pediatrics, 2Virology, University of Turku, and 3Turku University Hospital, Finland
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Background. Because the production of an effective respiratory syncytial virus (RSV) vaccine for infants is challenging, vaccination of other family members is one viable alternative to prevent severe RSV illnesses in infants. Methods. In a prospective study, we enrolled all family members of children who were hospitalized with RSV infection. Nasal swabs for RSV detection were obtained from all participating family members. Data on respiratory symptoms in the family members prior to and after the child’s admission were collected using standardized questionnaires. Results. At the time of or within 1 week after the index child’s hospitalization, RSV was detected in 40 (77%) of the 52 families and in 60 (47%) of 129 family members. Forty-nine (82%) of RSV detections in the family members were associated with respiratory symptoms. A sibling or a parent was the probable primary case of RSV in 30 (58%) families. Respiratory syncytial virus loads in the nasal swabs were signiﬁcantly higher (107.7) in index children than in their parents (105.1, P < .0001). Conclusions. In most cases, the likely source of an infant’s RSV infection is an older sibling or a parent. These ﬁndings support the strategy of reducing the burden of RSV in infants by vaccination of their family members. Keywords. bronchiolitis; family transmission; respiratory syncytial virus; respiratory tract infection; vaccination.
Since its discovery in the 1950s, respiratory syncytial virus (RSV) has been known as a major cause of acute lower respiratory tract infection in children [1, 2]. According to a recent estimate, the global annual death toll from RSV infection is 66 000–199 000 children