Over half of US kids infected with RSV in infancy, new data show

According to a US population-based birth cohort study in Emerging Infectious Diseases, 53.4% of babies were infected with respiratory syncytial virus (RSV) during infancy, and 2.8% were hospitalized.

The researchers also found that, among symptomatic infants, 44.1% had lower respiratory tract infections. The authors said these findings can act as a benchmark to monitor the effects of maternal vaccines and monoclonal antibodies administered to infants. 

The study included 1,680 children up to 1 year old identified during two RSV seasons, 2012 to 2013 and 2013 to 2014. RSV infection was found via active surveillance using PCR testing of nasal samples based on symptoms, and by passive surveillance by serum RSV antibody testing of all children at 1 year of age.

Of the eligible infants, 897 (53.4%) were infected with RSV in the first year of life and 783 (46.6%) were not. Active surveillance detected 36.1% of RSV infections in symptomatic infants, and 63.9% were found by serology alone.

Findings provide benchmark 

Among the 2.8% of infants hospitalized for RSV, 15.9% (95% confidence interval, 13.6% to 18.4%; n = 143) had RSV lower respiratory tract infections. There were no infant deaths from RSV infection. 

Being born during RSV season, attending daycare, and having siblings were all associated with RSV infection.

Our data are important estimates of the burden of RSV disease and risk factors for infection in healthy term infants.

“Our data are important estimates of the burden of RSV disease and risk factors for infection in healthy term infants. Our findings provide a benchmark to monitor the effects in the United States of recently available maternal vaccines and extended half-life monoclonal antibodies for severe RSV illness prevention in early life,” the authors concluded.