A Proof Of Concept For A Syndromic Surveillance System Based On Routine Ambulance Records In The South-west Of England, For The Influenza Season 2016/17

Thilo Reich; Marcin Budka

To establish the effect of different choices of d, the ascending area of pyrexia cases peak in 2016/17 was used to calculate a sliding CR d with varying d for the ascending slope where pyrexia cases increased ( Figure 2 CR 21 was chosen here as its values for the ascending slope were greater than 1, thus fitting the assumption that the slope represents an increase in case numbers. Although it included more outliers than CR 14 , it caused less delay than CR 28 , so is effectively a trade-off. To make the approach comparable between daily and weekly counts the same window is used for both sampling rates meaning a window of 21 days or 3 weeks for the daily and weekly counts respectively. The data was tested for auto correlation (not shown) and was found to be auto correlated over the time frame of a year, which would be expected for a seasonal infection. The auto correlation was minor for the 21 day window size and was therefore not further addressed.