Table 1. Country-specific influenza vaccination programmes and influenza surveillance systems, the Netherlands, Portugal and Spain, influenza seasons 2015/16–2017/18.

Characteristics	Netherlands	Portugal	Spain
Vaccination programme
Vaccine used	Inactivated trivalent vaccine
Target population	Population ≥ 60 years and medical risk groups (≥ 6 months-old)	Population ≥ 65 years and medical risk groups (≥ 6 months-old)	Population ≥ 65 years and medical risk groups (≥ 6 months-old)
Payment	Free of charge for the target groups	Free of charge for those ≥  65 years in public primary care units	Free of charge for target groups
Place of vaccination	Uptake via GPs	Uptake at pharmacy or healthcare units	Uptake mainly in public primary care units, but also in hospitals if needed, and in occupational risk units of public and private organisations
ILI surveillance system
Surveillance network	Nivel Primary Care Database – Sentinel Practices	Rede Médicos-Sentinela	Spanish Influenza Sentinel Surveillance System
ILI case ascertainment and swabbing for confirmation	Weekly notification by sentinel GPs of cases meeting the ‘Pel-criteria’ [42]: sudden onset of symptoms AND fever (at least 38 °C) AND at least one of the following symptoms: cough, rhinorrhoea, sore throat, frontal headache, retrosternal pain or myalgia. GPs are recommended to swab at least the first two ILI patients attending each week.a	Weekly notification by sentinel GPs of cases meeting the EU ILI case definition	Weekly notification by sentinel GPs of cases meeting the EU ILI case definition [43]. GPs are recommended to swab the first two patients attending each week.
Laboratory confirmation of influenza	RT-PCR testing of nasopharyngeal/nose and throat swabs for influenza confirmation. If the test is positive for influenza, further tests are performed to determine virus type/subtype/lineage.
Method of estimating positivity rate	Number of positive influenza detections among the swabbed respiratory samples × (1/sensitivity of RT-PCR); Sensitivity of RT-PCR = 0.95	Number of positive influenza detections among the swabbed respiratory samples

EU: European Union; GP: general practitioner; ILI: influenza-like illness.

^a Patients < 65 years of age consulting on Monday through Wednesday and all ILI patients 65 years and older during the whole week.