Trainees and experts discuss influenza data and statistical methods included in the PISA tool (Photo: WHO).

26 November 2018 – From 1 to 4 October, in a premiere event for the Region, over 25 influenza experts converged in Tunis for a training workshop on influenza baseline setting and threshold value determination for so-called Pandemic Influenza Severity Assessments (PISAs). By organizing and facilitating the course, WHO’s Regional Office for the Eastern Mediterranean aimed to support countries in their understanding of the PISA tool, and how surveillance data can be used to better assess the severity of influenza.

Every year, influenza epidemics cause about 3 to 5 million cases of severe illness, and about 250 000 to 500 000 deaths. No countries or demographic groups are exempt from this threat. Using historical baseline data, and by closely monitoring expected as well as unusual fluctuations in influenza incidence prevalence over time, countries will now be better able to detect influenza epidemics, determine seasonality and adequately plan and respond to seasonal and pandemic influenza and prevent unnecessary illness or death. 

Currently, 19 of 22 countries in the Region conduct influenza surveillance as part of their improving pandemic influenza preparedness efforts, 15 of which participated in this workshop. By collecting and analysing influenza surveillance data, countries can now identify the start and end of their influenza season and the level of influenza activity that is to be expected. The same data can also be used to detect unusual events related to influenza, by establishing alert and epidemic thresholds.

Over the course of the four day event, surveillance officers deepened their expertise using standard statistical methods and techniques to determine these baseline and threshold values for their countries. With the values in hand and with ongoing support from WHO’s Eastern Mediterranean Regional Office, the officers can analyse their countries’ flu seasonality as well as identify the relevant “cut-off” points to identify unusual influenza activity.