To identify clinical characteristics of severe respiratory syncytial virus (RSV) in neonatal period and early infancy and provide information in clinical practice.

Twelve neonates and young infants (<6 months) who were infected by respiratory syncytial virus and required mechanical ventilation between March 2005 and July 2007 were enrolled. Diagnosis of RSV infection was made based on the positive results by rapid antigen immunoassay or polymerase chain reaction.

There were four premature infants, of whom three were near-term. Birth weight of subject patients was 2.8±0.6 kg, gestational age was 37±2 weeks and the age at the time of admission was 35±15 days. Nine of them showed apnea and in five patients, apnea itself was an indication for mechanical ventilation. In seven of the apneic patients, apnea was the first manifestation of RSV infection. In three of these seven apneic patients, apnea preceded definite respiratory distress signs or typical stethoscopic findings by 1-3 days. Mean duration of mechanical ventilation was 3±2 days, and mean duration of stay in intensive care unit was 6±2 days.

RSV is a major cause of severe respiratory tract infection in term or near-term infant younger than 2 months. For apnea could be the first manifestation of the RSV infection, high level of suspicion is required in practice of neonates or young infants who show any upper respiratory infection symptoms during RSV season.