Oseltamivir for Treatment of Influenza in Infants Less Than One Year A Retrospective Analysis

Background: Influenza causes proportionately more hospitalizations and deaths in infants in their first year of life than in older children. Oseltamivir is an effective treatment for childhood influenza, but few data are available in infants <1 year. Methods: Medical records of infants <1 year admitted to hospital during the influenza seasons 2003-2007 were retrospectively analyzed to evaluate clinical presentation, and safety and outcome with oseltamivir therapy. Eligible infants were those with fever (>38 degrees C), influenza-like symptoms of sudden onset, positive rapid influenza test and parental consent, who received oseltamivir within 48 hours of the start of symptoms. Infants vaccinated against influenza or receiving immunosuppressants were excluded. Results: In 157 evaluable infants (mean age 6.3 [SD 3.2] months; 86 boys), the most common presenting symptoms other than fever were rhinitis, pharyngitis, cough, feeding difficulties, and otitis media. During treatment, additional symptoms were observed in 78 (50%) infants; most of these were gastrointestinal (vomiting and diarrhea) and of mild intensity. Fever resolved in 128 (82%) infants within 36 hours of starting oseltamivir (136 [87%] within 48 hours). Complications were recorded in 84 patients (54%), the most serious of which were meningitis in 1 infant (1%), pneumonia in 9 (6%), and otitis media in 2 (1%). Twenty infants received antibiotics for secondary infections (10 [6%] before admission). Conclusions: The clinical presentation of influenza and outcome of oseltamivir treatment in infants <1 year was similar to that previously reported in older children, but mild gastrointestinal symptoms were common.