Improving ILI Surveillance using Hospital Staff Influenza-like Absence (ILA)

Lydia Drumright, Simon Frost, Mike Catchpole, John Harrison, Mark Atkins, Penny Parker, Alex J. Elliot, Douglas M. Fleming, Alison H. Holmes


Estimates of influenza based on influenza like illness (ILI) may not capture the full spectrum of illness or result in early warning. We tested a syndromic surveillance method using hospital staff influenza like absence (ILA) to potentially enhance ILI. Rates of ILA were compared to regional surveillance data on ILI and confirmed positive influenza A test results (PITR) in hospitalised patients. ILA demonstrated accurate seasonal trends in influenza as defined by ILI, but provided more realistic estimates of the relative burden of pH1N1, and potentially earlier warning than ILI and PITR, which is likely to improve accuracy of influenza monitoring.

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Online Journal of Public Health Informatics * ISSN 1947-2579 *