RSV Hospitalizations in Comparison With Regional RSV Activity and Inpatient Palivizumab Administration, 2010-2013.

OBJECTIVES: To compare pediatric respiratory syncytial virus (RSV) hospitalizations in the United States to regional RSV activity and inpatient palivizumab administration.

METHODS: We characterized inpatients, excluding newborns, with RSV from the Pediatric Health Information System (July 2010-June 2013). RSV regional activity timing was defined by the National Respiratory and Enteric Virus Surveillance System. RSV hospitalization season (defined by at least 3 SDs more than the mean regional baseline number of RSV hospitalizations for 3 consecutive weeks) was compared with RSV regional activity season (2 consecutive weeks with ≥10% RSV-positive testing). Logistic regression was used to determine predictors of hospitalization timing (ie, during or outside of regional activity season). We also assessed the timing of inpatient palivizumab administration.

RESULTS: There were 50 157 RSV hospitalizations. Mean RSV hospitalization season onset (early November) was 3.3 (SD 2.1) weeks before regional activity season onset (early December). Hospitalization season offset (early May) was 4.4 (SD 2.4) weeks after activity season offset (mid-April). RSV hospitalization and activity seasons lasted 18 to 32 and 13 to 23 weeks, respectively. Nearly 10% of hospitalizations occurred outside of regional activity season (regional ranges: 5.6%-22.4%). Children with chronic conditions were more likely to be hospitalized after regional activity season, whereas African American children were more likely to be hospitalized before. Inpatient palivizumab dosing was typically initiated before the start of RSV hospitalizations.

CONCLUSIONS: There is regional variation in RSV hospitalization and activity patterns. Many RSV hospitalizations occur before regional activity season; high-risk infants may require RSV immunoprophylaxis sooner.