Abstract
Background There is uncertainty about the burden of severe outcomes associated with RSV and influenza in different subgroups of children defined by age, as well as age and presence of underlying health conditions.
Methods We have applied previously developed methodology to estimate the rates of influenza and RSV-associated hospitalizations with different diagnoses in different age subgroups of US children between the 2003-04 through the 2009-10 seasons.
Results The average annual rates (per 100,000) of influenza and RSV-associated hospitalizations for any cause excluding asthma (ICD-9 code 493) in the principal diagnosis with a respiratory cause (ICD-9 codes 460-519) in the diagnosis (either principal or secondary) were 173.1(95%CI (134.3,212.6)) (influenza) vs. 2336(2209,2463) (RSV) (age <1y); 77.9(51.1,105.2) vs. 625.7(540,711.5) (age 1y); 56.3(40.9,72.2) vs. 324.2(275.1,375) (age 2y); 44.6(32.9,56.6) vs. 172.2(134.2,211) (age 3y); 36.4(27.7,45.3) vs. 89.7(60.6,117.8) (age 4y); 36.6(29.3,43.9) vs. 62.3(38.8,86.4) (ages 5-6y); 20.5(16.3,24.6) vs. 30.2(16.1,43.9) (ages 7-11y); and 16.1(10.6,21.7) vs. 36.9(17.8,55.9) (ages 12-17y). The rates of RSV-associated hospitalizations with asthma as a secondary (non-principal) diagnosis were 162.6(143.6,181.6) (age <1y), 144.7(120.8,168.2) (age 1y), 99.5(82.3,116.8) (age 2y), 60.9(46.4,75.3) (age 3y), 23.5(10.7,36.4) (age 4y), 16.1(5.1,27) (ages 5-6y), 11.4(4.7,18.3) (ages 7-11y), and 15.8(4.9,26.7) (ages 12-17y).
Conclusions The estimated rates of RSV-associated hospitalizations in young children are high, with those rates declining rapidly with age. We hope that such estimates could provide one of the ingredients for evaluating the potential impact of RSV vaccine administration in young children. Additionally, the estimated rates of RSV-associated hospitalizations with asthma as a secondary diagnosis in young children, combined with data on the prevalence of asthma in those age groups suggest very high rates of RSV-associated hospitalizations in young children with asthma. Those children may be considered as potential target groups for RSV-related mitigation efforts.