Influenza syndromic surveillance based on sentinel pharmacies in Catalonia (Spain) in 2017-2020

Abstract

Objective: To analyse influenza surveillance data obtained from sentinel pharmacies of Catalonia, Spain, in 2017−18, 2018−19 and 2019-20 influenza seasons. Methods: Influenza surveillance information was collected from a representative sample of community pharmacies of Catalonia. Influenza-like cases were identified based on the ECDC criteria.The Chi-square test and Odds ratios were used to compare percentages between different population groups, with a p <0.05 considered as statistically significant. The screening method was used to assess influenza vaccination effectiveness. The moving epidemic method (MEM) was used to assess influenza epidemics in the three influenza seasons. Results: A total of 836, 1,000 and 587 influenza-like cases were reported in 2017−18, 2018−19 and 2019−20. Sentinel pharmacies dispended medications to 94-98% of patients. Paracetamol, cough medication, ibuprofen and antihistamines were dispended to more than 25% of patients. Dispensation of antibiotics decreased by 57% from 2017-18 to 2019-20 (OR = 0.45, 95% CI: 0.28-0.74, p < 0.001). Physicians prescribed medications to 30-38% of influenza-like patients. The influenza vaccination effectiveness in individuals aged 65 or more years was 51.4% (95% CI: 41.9−60.7) in 2018-19 and 67% (95% CI: 53.4−79.8) in 2019-20 influenza seasons. Influenza epidemics occurred from week 50 of 2017 to week 7 of 2018; from week 51 of 2017 to week 8 of 2019; and from week 2 to week 7 of 2020. Conclusion: The influenza surveillance system based on sentinel pharmacies provided consistent information on the influenza epidemic, influenza morbidity not assisted in health centres and medications used to treat influenza-like cases during 2017−2019.