Influenza virus in pediatrics. A reason for hospitalization

Influenza infection in infants and children has been classically underestimated due to its non-specific symptoms, which sometimes overlap those of other respiratory viruses. Infants under 24 months are a risk group and school-aged children are a major source of influenza infection. The aim of this study was to describe the clinical and epidemiological characteristics of children hospitalized for flu, including co-infections and the differences as compared to other respiratory viruses. The effectiveness of a test for rapid diagnosis of this condition was assessed. Prospective, descriptive study in children < 5 years of age hospitalized from 1 December 2003 to 28 February 2004 with respiratory processes or fever of unknown origin. Polymerase chain reaction (PCR) testing for influenza A (IA) and B, respiratory syncytial virus A (RSV-A) and B, and parainfluenza 1, 2 and 3 was performed in nasopharyngeal aspirate, as well as a test for rapid diagnosis of influenza. A total of 203 samples were included. PCR was positive for influenza in 11.3% (23/203); IA in 21 cases (20 H3N2, 1 H1N1). Co-infections were frequent (10/23), mainly IA with RSV-A. The rapid diagnostic test had a sensitivity of 45.5%. Median age of patients with flu was 4.87 months (5 days-3.5 years); 69.5% were < 24 months. Gastrointestinal symptoms were associated with fever and respiratory symptoms more often than in other viral infections (P < 0.05). Only 2.9% of patients with a recommendation for flu vaccination had received the vaccination. Flu is a major cause of hospitalization in infants and children, particularly those aged < 24 months. Early diagnosis of this condition may avoid unnecessary use of additional tests and antibiotics. Vaccination coverage is low; vaccination between 6 and 24 months seems advisable.