To determine the contribution of influenza and respiratory syncytial
virus (RSV) as the cause of lower respiratory tract infection (LRTI) associated hospitalizations
during the first year of the influenza A(H1N1) 2009 pandemic and to assess the severity of illness
during the second pandemic wave.
Methods: Patients admitted with LRTI from April 2009 through March 2010 were assessed for
the presence of influenza and RSV. Pandemic influenza virus was detected by means of a nested
RT-PCR assay and/or the CDC’s real time-PCR protocol. RSV was detected using a one-step RTPCR
assay. The characteristics of patients admitted during the first and second pandemic outbreaks
were compared.
Results: 657 patients with LRTI were admitted during the study period. Pandemic influenza
virus was detected in 180 and RSV in 133. Influenza was the most common cause of infection
in adults, while RSV was more common in children. There were no differences in disease severity
between the first and second pandemic outbreaks.
Conclusions: Pandemic influenza virus was associated to increased numbers of hospitalizations
and deaths; particularly in adults. The severity of the first and second pandemic outbreaks was
similar. RSV continues to be the main pathogen responsible for hospitalizations in young children.
ª 2010 The British Infection Society. Published by Elsevier Ltd. All rights reserved.