Flu season in Spain
Current flu activity in Spain — based on ECDC ERVISS weekly data, set against the parallel COVID-19 and RSV trajectories.
Current situation: Influenza
In week 15 of 2026, activity of influenza (seasonal flu) in Spain is low. The trend — derived from clinical surveillance — is stable. Over a four-week comparison, a clear decline is visible.
The classification is based on the ECDC ERVISS weekly reports, drawing on data from the Spanish SiVIRA acute respiratory infection surveillance system operated by the Instituto de Salud Carlos III (ISCIII). Seasonally, infection waves in Spain typically peak between December and February; activity is usually markedly lower during the summer months. How severe a given season becomes depends on the circulating virus variant and the population's immune status, among other factors.
Data sources and methodology
The current picture for Spain is built on the European Respiratory Virus Surveillance Summary (ERVISS), published weekly by the European Centre for Disease Prevention and Control (ECDC). SiVIRA (Instituto de Salud Carlos III, ISCIII) is the national public-health authority that feeds ERVISS with sentinel primary care and virology data.
ECDC ERVISS
ERVISS is ECDC's weekly pan-European surveillance summary for influenza, SARS-CoV-2 and RSV. National authorities — in Spain's case SiVIRA (Instituto de Salud Carlos III, ISCIII) — submit harmonised indicators every week, which ECDC publishes in a standardised dataset on Thursdays. Using ERVISS rather than each country's native portal ensures cross-country comparability.
ILI / ARI consultation rates and positivity
SiVIRA (Instituto de Salud Carlos III, ISCIII) operates a sentinel network of general practices that report weekly rates of patients consulting for influenza-like illness (ILI) or acute respiratory infection (ARI). A subset of patients is swabbed and tested by reference laboratories, producing pathogen-specific positivity rates for flu, SARS-CoV-2 and RSV.
Why this source
Combining consultation incidence with virological positivity yields a pathogen-specific weekly incidence signal (ILI × positivity / 100). This is the standard European methodology and provides a more robust view than either indicator alone — consultation rates capture illness burden, positivity confirms which pathogen is driving it.
Qualitative classification
The “low”, “moderate” and “high” categories follow seasonal reference values and epidemiological thresholds calibrated to match our classifications for other countries. The ILI × positivity / 100 product is scaled to comparable thresholds using a divisor of 3, which aligns European sentinel peaks with the consultation-equivalent scale used elsewhere. Data refreshes weekly when ECDC publishes the latest ERVISS update, typically on Thursdays.
Frequently asked questions
When is flu season in Spain?
Flu in Spain typically begins rising in December, peaks between January and February, and eases through March. The Instituto de Salud Carlos III (ISCIII) runs the SiVIRA integrated surveillance system for respiratory viruses and publishes weekly bulletins. Timing and intensity vary season to season depending on the dominant influenza subtypes and residual immunity in the population.
How does ISCIII classify flu severity?
Through SiVIRA, ISCIII publishes weekly reports covering primary-care incidence, hospital admissions for severe acute respiratory infection, ICU admissions, and virological positivity from sentinel networks. Activity is described in qualitative bands against historical thresholds. Spain also contributes to the ECDC European Respiratory Virus Surveillance Summary (ERVISS), so the Spanish curve can be compared directly with other EU countries.
How is flu surveillance organised in Spain?
SiVIRA integrates primary-care and hospital streams. Sentinel GPs and paediatricians record ILI consultations and submit swabs for virological testing at reference laboratories. Hospital surveillance captures severe acute respiratory infection admissions and ICU cases, coordinated between ISCIII and the autonomous communities. Results are published weekly and feed into both national bulletins and the ECDC ERVISS platform.
Is the flu vaccine free in Spain?
Spain offers free seasonal flu vaccination through the Sistema Nacional de Salud to groups at higher risk, including adults aged 60 or 65 and over depending on the autonomous community, pregnant women, people with certain long-term conditions, children in defined age ranges, healthcare workers, and carers. ISCIII and the Ministerio de Sanidad publish coverage data alongside weekly surveillance in SiVIRA.
How does this year's Spanish flu season compare to previous ones?
Each season is shaped by the dominant influenza subtype and accumulated immunity. SiVIRA reports plot current indicators against recent seasons, and ECDC ERVISS places Spain in its European context. Some seasons in Spain peak sharply in January, others are drawn out into March. The weekly bulletins make clear whether current activity sits above or below the recent historical average.
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