Influenza sentinel surveillance: Correlates of timely reporting and viral specimen yield

Introduction

Influenza sentinel surveillance is one of the surveillance systems used to track Influenza activity in the United States. No published study has examined correlates of reporting by ILI sentinel providers and specimen submission patterns.

Background

Pennsylvania had 56 active sentinel providers during the 2008/2009 season. Each sentinel provider was informed, by phone and mail, on how to report ILI and submit specimens to the state lab. In this study we present data on why some sentinel providers regularly report and why others do not, and compare specimen submission rates and viral yield of sentinel specimens compared to specimens provided by hospitals.

Methods

We surveyed all 56 sentinel providers to asses timeliness of reporting, reporting rate and specimen submission practices over a four months period - December to March of the 2008/09 Influenza season. We abstracted state lab data to asses the specimens submission and viral yield.

Results

We applied multivariate logistic models to the data and to show major differences in:

- Viral yield between sentinel provider and non sentinel sites

- Predictors of increased sentinel reporting included, small practice, years of experience with sentinel surveillance, increased communication and feedback from the lab and receipt of surveillance data.

Conclusion

Our data show that sentinel providers are reliable sources of Influenza specimens for virological testing and antigenic characterization. There is need to improve the communication of virology results by state labs and CDC to sentinel providers and the public. Non monetary incentives can keep sentinel providers engaged in Influenza surveillance.