Impact of the 2009 Influenza Pandemic on Pneumococcal Pneumonia Hospitalizations in the United States

Daniel M. Weinberger*, Lone Simonsen, Richard Jordan, Claudia Steiner, Mark Miller, Cecile Viboud

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

BACKGROUND:
Infection with influenza virus increases the risk for developing pneumococcal disease. The A/H1N1 influenza pandemic in autumn 2009 provided a unique opportunity to evaluate this relationship.

METHODS:
Using weekly age-, state-, and cause-specific hospitalizations from the US State Inpatient Databases of the Healthcare Cost and Utilization Project 2003-2009, we quantified the increase in pneumococcal pneumonia hospitalization rates above a seasonal baseline during the pandemic period.

RESULTS:
We found a significant increase in pneumococcal hospitalizations from late August to mid-December 2009, which corresponded to the timing of highest pandemic influenza activity. Individuals aged 5-19 years, who have a low baseline level of pneumococcal disease, experienced the largest relative increase in pneumococcal hospitalizations (ratio, 1.6 [95% confidence interval {CI}, 1.4-1.7]), whereas the largest absolute increase was observed among individuals aged 40-64 years. In contrast, there was no excess disease in the elderly. Geographical variation in the timing of excess pneumococcal hospitalizations matched geographical patterns for the fall pandemic influenza wave.

CONCLUSIONS:
The 2009 influenza pandemic had a significant impact on the rate of pneumococcal pneumonia hospitalizations, with the magnitude of this effect varying between age groups and states, mirroring observed variations in influenza activity.
Original languageEnglish
JournalJournal of Infectious Diseases
Volume205
Issue number3
Pages (from-to)458-465
ISSN0022-1899
DOIs
Publication statusPublished - Feb 2012
Externally publishedYes

Bibliographical note

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