As flu season continues to ramp up, public health surveillance is an essential tool to identifying outbreaks early and having necessary, community-level data to be able to respond to health emergencies appropriately. Surveillance is the ongoing and systematic collection and interpretation of health related data, and is typically based on information gathered from medical records, pharmacies, laboratories, or even school absentee reports. Traditional surveillance systems often require an interaction with the medical system such as through an outpatient clinic or pharmacy to obtain a case report or other data. A complement to traditional surveillance systems is participatory surveillance, which engages the general public in reporting. Its strengths lie in the speed at which data can be made available, the ability to scale the technology to cover large populations at a low cost, and the ability to cover populations that might not otherwise be tracked, which could be a valuable complement to track individuals not seeking care.
Flu Near You is one weapon in the arsenal of a health department when tracking and combatting illness in the community. Flu Near You is a participatory surveillance system, engaging the general public directly in reporting on their health. A weekly email asks participants to answer a brief survey through the website or the mobile application. The survey consists of a set of ten symptoms and if users report any symptoms, a few follow up questions appear, including the date of onset. Answers that meet the definition of influenza-like-illness (ILI) are displayed on a digital map showing ILI rates in a given area.
NACCHO has been engaging with several local health departments to explore how Flu Near You can supplement traditional surveillance systems, and through ongoing conversation it became clear that to make this tool most successful, it is necessary to build up a local user base. To help local health departments and other partners who are looking to use and promote Flu Near You in their communities, NACCHO created Flu Near You: A Guide to Engaging in Participatory Disease Surveillance. It contains general resources about participatory disease surveillance systems, information about Flu Near You, resources for integrating Flu Near You into existing programmatic efforts, and materials to use for promoting the tool.
While it is necessary to increase local participation to make Flu Near You a useful surveillance tool, the number of active users needed to gain useful information from Flu Near You is not as high as you might think. Eric Bakota, an epidemiologist at the Houston Department of Health and Human Services, has been analyzing a subset of Flu Near You data and will present his findings in December at the International Society for Disease Surveillance Conference. He summarized his experience with Flu Near You and some of his findings for NACCHO:
“Flu Near You is a tool I initially approached with a lot of skepticism,” said Eric, “but the data have so far indicated that the platform is a reliable indicator of influenza activity in the United States.” Eric determined this by correlating Flu Near You data with CDC’s ILINet data and lab confirmed influenza data. He found that generally the correlation is very high, above .90. The logical next question for him was to determine how reliable the data is at a local level. By bootstrapping the data at smaller and smaller sample sizes he found the correlation to stay fairly strong until there are fewer than 200 weekly participants. Eric noted that, “After 200 there is a pretty sharp drop off in the signal of ILI activity. I am very hopeful that Flu Near You can be a sound tool for smaller local health departments to be able to have and use local data if they can reach the goal of roughly 200 weekly participants.”
If you are interested in learning more about Flu Near You, promoting it in your community, or participatory disease surveillance, view Flu Near You Guide to Engaging in Participatory Disease Surveillance.