Title : Syndromic surveillance of influenza based on sentinel pharmacies
Abstract:
Influenza is responsible for seasonal epidemics every winter, with great impact on the health system. Community pharmacies are involved in the prevention and control of influenza and other diseases. In Catalonia, Spain, a new influenza surveillance system based on 60 community sentinel pharmacies was implemented from 2017 to 2023. The results obtained with this surveillance system were assessed by analysis the number of influenza-like-illness (ILI) cases, ILI symptoms, medications dispensed by pharmacies to ILI cases, medications prescribed by physicians to ILI cases, and influenza vaccine effectiveness among persons aged ≥65 years. Influenza/ILI activity was detected during each influenza season using the moving epidemic method. Influenza epidemics were detected in the 2017-2018, 2018-2019 and 2019-2020 influenza seasons, while they were absent in the 2020-2021 and 20212022 influenza seasons. The most frequent medications dispensed to ILI cases included paracetamol, cough medications, ibuprofen and antihistamines. Oseltamivir had been prescribed to <1% of ILI cases attended by pharmacies. 31−38% of ILI cases attended by pharmacies had received a prior medical visit during the influenza seasons studied. Dispensation percentages of 94−98% were registered during the influenza seasons studied. Physicians had prescribed medications to 31−38% of ILI cases during the influenza seasons studied. The effectiveness of influenza vaccination in persons aged ≥65 years during the last two seasons assessed (2021-2023) was 76% (95% IC: 37.5−90.8%) among persons with a negative test and 75.4% (95% IC: 49.9−87.9%) among all ILI cases. The analysis of the information collected by the surveillance system based on pharmacies showed that this new surveillance system was able to detect the influenza epidemic and provide complementary information complementary of that obtained using traditional influenza surveillance systems.
