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Syndromic Surveillance Confirmation of Extended Influenza Season


The 2003-2004 influenza season was notable for the early, intense and widespread circulation of a Type A drift variant and a resulting rush on vaccine followed by an abrupt decrease in activity by mid-January. By contrast, the 2004-2005 influenza season began with a national vaccine shortage preceding any influenza activity with the resulting need for close monitoring of influenza activity.

The Connecticut Department of Public Health developed its first syndromic surveillance system in September 2001 to monitor for possible bioterrorism events and emerging infections. This system, known as the Hospital Admissions Surveillance System, receives daily reports from all 32 Connecticut acute care hospitals on their total unscheduled admissions in various diagnostic/syndromic categories. Information from one category, pneumonia admissions, has been tracked throughout the last four years as an indicator of influenza activity. The information has been utilized to supplement data from laboratory-confirmed influenza testing. The contrasts between the 2003-04 and 2004-05 influenza seasons provided an opportunity to further examine the specificity of changes in pneumonia admissions as an index of severe influenza activity.



This paper examines the continued usefulness through the 2004-05 influenza season of a hospital admissions-based syndromic surveillance system as a supplement to laboratory surveillance to monitor severe influenza.

Submitted by elamb on