Respiratory syncytial virus immunoprophylaxis: impact on epidemiology

To better understand the spectrum of disease among hospitalised children infected with respiratory syncytial virus (RSV) and to assess the potential impact of passive immunoprophylaxis on RSV hospitalisation rates, we analysed all patients infected with RSV who were admitted to a paediatric teaching hospital over a 3-year period.

We performed a retrospective chart review of all paediatric patients from whom RSV was isolated between October 1, 1994 and April 30, 1997.

A total of 255 children infected with RSV were hospitalised during this 3-year period. 246 (96%) patients had community acquired infections and 9 (4%) had nosocomial infections. Excluding patients with nosocomial infections, the mean length of hospital stay was 4.7 days. 70 (28%) children were admitted to the intensive care unit, 32 (13%) were intubated and there was a total of 4 deaths (1.6%). 48% of hospitalised patients were in 1 of 4 previously recognised high risk groups. Of the 52% of patients not in a defined high risk category, 42% were otherwise healthy infants (>6 weeks of age) and 10% had chronic underlying illnesses generally not associated with an increased risk of severe RSV disease. Patients not in a defined high risk category accounted for 46% of total hospital days.

In order to reduce overall RSV hospitalisation rates and the economic burden to society, programmes for disease prevention must be directed at healthy infants as well as children in recognised high risk categories. Even if all currently eligible candidates were to have received passive immunoprophylaxis, which yields about a 50% reduction in hospitalisation rates, the number of RSV hospitalisations in our 3-year study would have been reduced by no more than 9%. Without development and widespread use of an effective RSV vaccine, a major impact on RSV-induced hospitalisation is unlikely.