Comparative Characteristics of the 2009 Pandemic Influenza A (H1N1) Virus and 2010-2011 Seasonal Influenza in Pediatric Patients.

BACKGROUND

In March 2009 the pandemic influenza A (H1N1) strain was identified. The disease initially appeared to be accompanied by complications and high mortality rates. It became an endemic virus during the influenza season in our region, along with the classical seasonal H3N2.

OBJECTIVES

To identify the burden of pandemic influenza, its effect in pediatric patients, and complicated hospitalizations, compared to seasonal influenza years after the pandemic.

METHODS

A retrospective observational study was conducted at a tertiary hospital. Data were collected from the medical records of all children who were hospitalized from April 2009 to 2011 with laboratory-confirmed influenza.

RESULTS

Of 191 patients with influenza, 100 had the 2009 pandemic influenza, 62 had seasonal influenza, and 29 had H1N1 in 2010-2011. Patients with the 2009 H1N1 were characterized by older age, more co-morbidity conditions and more symptoms including fever, cough and rhinitis on admission. No significant differences in outcomes between the groups were recorded. Of patients hospitalized with pandemic influenza in 2009, 28% had complicated hospitalizations, compared with 17.7% of patients hospitalized with seasonal influenza in 2010-11. Children with pandemic influenza received more oseltamivir (Tamiflu®) (94% vs. 19.4%, P < 0.001) and more antibiotics than the other groups.

CONCLUSIONS

The type of influenza had no effect on outcome. There were no significant differences between groups in the percentages of in-hospital mortality, admission to intensive care units, prolonged hospitalization (> 9 days), or the development of complications during hospitalization.