Distribution of Respiratory Syncytial Virus Subtypes A and B Among Infants Presenting to the Emergency Department With Lower Respiratory Tract Infection or Apnea

This is the largest epidemiologic study in EDs reporting trends in RSV subtypes. RSV subtypes A and B were documented in both seasons across all US regions studied and detected in September to May. The results of this study support suggestions from smaller studies that RSV A may be more virulent than RSV B; however, more quantitative assessments of disease severity are needed.