What's going around in Spain?
Influenza: Low, COVID-19: Low, RSV: Low
Not many. Influenza, COVID-19 and RSV are all at low activity in Spain (as of 4 Oct 2026).
Data window: Week 40 · Sep 28 – Oct 4 · Source: ECDC (weekly) · Next update Fri, Oct 16
Current activity
Source: ECDC ERVISS, ECDC Data. Published weekly, about one week behind.
Frequently asked questions
How is overall respiratory-illness activity tracked in Spain?
ISCIII's SiVIRA system integrates flu, COVID-19, RSV, and other respiratory viruses into a single weekly bulletin. It combines sentinel primary-care data, hospital and ICU admissions for severe acute respiratory infection, and virological positivity. Spanish data also feeds the ECDC ERVISS platform. On infectrisk.com we summarise this into a qualitative low/moderate/high classification.
Did Spain experience a “tripledemic”?
“Tripledemic” is a media label for the simultaneous winter circulation of flu, COVID-19, and RSV. Spain saw clear co-circulation of all three pathogens in the 2022–2023 season, with strong pressure on paediatric care driven by RSV and on adult critical care. Co-circulation has continued in subsequent winters, with the relative intensity of each pathogen varying season to season.
Why do respiratory illnesses peak in a Spanish winter?
Even in Spain's milder climate, winter drives a clear peak. Many respiratory viruses remain stable longer in cold, dry indoor air, heated buildings lower humidity in ways that weaken airway defence, and people mix indoors more during winter. Schools and holiday gatherings accelerate transmission just as seasonal immunity is at its lowest.
What is “immune debt”?
“Immune debt” describes how, after prolonged low circulation of a pathogen, such as during the strict COVID-19 restrictions, population-level immunity gradually declines and subsequent seasons can be unusually severe. Spain's post-pandemic RSV and flu seasons showed features consistent with this effect. It is a temporary catch-up phenomenon rather than a permanent immune change.
How does ISCIII decide that activity is “high”?
ISCIII uses thresholds derived from historical SiVIRA data. Current sentinel incidence, hospitalisations, ICU admissions, and positivity rates are compared against baselines from past non-epidemic weeks and against severe-season reference points. When several indicators cross into elevated bands at once, the weekly bulletin classifies activity as high, using the same framework that structures Spain's ECDC ERVISS contribution.