Clinical features, oseltamivir treatment and outcome in infants aged <12 months with laboratory-confirmed influenza A in 2009.

BACKGROUND Data on the use of oseltamivir in infants is limited. We documented the clinical presentations of infants aged <12 months hospitalized with laboratory-confirmed influenza A in the southern hemisphere winter of 2009 and compared outcomes in relation to oseltamivir therapy. METHODS Data were extracted from prospectively collected and collated influenza case reports (June-September 2009) ascertained through Paediatric Active Enhanced Disease Surveillance, an in-patient surveillance system operating at the Children's Hospital at Westmead (CHW), Sydney, NSW, Australia. Nosocomial cases were excluded. RESULTS Of 56 infants with definite influenza (35 pandemic H1N1 2009) admitted to the CHW, 20 were treated with oseltamivir. Overall, 12 (60%) of those treated with oseltamivir were aged <6 months. Cough, fever and coryza were the most common clinical features (≥70%). Vomiting was present on admission in 31.4%. All 7 cases presenting with vomiting then given antiviral treatment had reduction of vomiting and the other 13 did not develop vomiting on treatment. There were three infants with hypoxaemia (oxygen saturation ≤93%) on presentation in the treatment group compared with none in the control group (P=0.04). The median duration of hospital stay was the same in both groups (2.5 days). CONCLUSIONS The use of oseltamivir was well tolerated in hospitalized infants. Vomiting, one of the widely reported side effects of oseltamivir, was found to be more a presenting symptom of influenza than a side effect of oseltamivir. Based on pulse oximetry, oseltamivir-treated cases may have been more severe on presentation, but there was no significant difference in length of hospital stay.