Spain's flu activity is still low, but early changes are appearing among younger people. Álvaro Torres explains why international surveillance helps track variants and plan prevention before the next season takes shape.
From 7 to 13 September 2026, influenza activity in Spanish primary care reached 8.2%, according to the ISCIII/SiVIRA surveillance system. The figure remains below the epidemic threshold, but it is higher than a year ago. Surveillance teams have also seen a small rise among younger people. An early signal.
Álvaro Torres says international monitoring matters because a change in circulating viruses can show up in one region before it reaches another. The data cannot provide a complete forecast. It can give public health authorities more time to assess the risks of the next season.
The southern hemisphere may offer some of the clearest clues. Torres calls the study of circulating variants there one of the strongest predictive indicators. The pattern does not always move neatly from south to north. Tropical regions follow a different rhythm because influenza can circulate throughout the year. Those areas may act as both sources and destinations for transmission.
For the 2027 southern hemisphere influenza season, WHO recommended egg-based vaccine components similar to A/Missouri/11/2025 (H1N1)pdm09, A/Darwin/1454/2025 (H3N2) and B/Tokyo/EIS13-175/2025 (B/Victoria).
The uncertainty makes year-round surveillance necessary. Spanish weekly reports describe the current increase as limited and non-epidemic. The clearest early changes are among younger age groups.
Most detected viruses are influenza A. Hospitalised patients are mainly aged 65 or over. The early rise among younger people is limited, but it needs close monitoring. The start and strength of a flu season can change from one year to the next, according to the expert cited by Europa Press.
Severe cases still follow the usual seasonal pattern. Older adults carry much of the hospital burden.
On 25 September 2026, the World Health Organization updated its recommended vaccine composition for the 2027 southern hemisphere influenza season. For egg-based vaccines, it recommended strains similar to A/Missouri/11/2025 (H1N1)pdm09, A/Darwin/1454/2025 (H3N2) and B/Tokyo/EIS13-175/2025 (B/Victoria). For cell-based and recombinant platforms, the recommendations were A/Missouri/11/2025, A/Darwin/1415/2025 and B/Pennsylvania/14/2025.
Those choices matter for Spain because vaccine composition is set well before the season begins. Laboratories in different countries supply the data. The WHO says its recommendations come from global consultation and analysis of circulating viruses, not from conditions in one country alone.
It is still too early to know how closely the vaccine will match the viruses that eventually spread in Spain. If the prediction is inaccurate, vaccine effectiveness falls, Torres says.
ECDC’s ERVISS surveillance follows influenza alongside RSV and SARS-CoV-2 across the EU/EEA and the WHO European Region. This integrated approach helps compare respiratory-virus trends instead of treating influenza as an isolated seasonal signal.
The European picture is wider than influenza alone. ECDC's ERVISS reports track influenza, RSV and SARS-CoV-2 across the EU/EEA and the WHO European Region. Recent updates place the viruses against the return of schools and workplaces, although activity remains below epidemic levels.
Vaccination is not expected to prevent every infection. Its main purpose is to reduce severe illness, hospital admissions and deaths linked to influenza. Improving coverage among vulnerable groups remains difficult.
Spain's surveillance network brings the autonomous communities together. It tracks more than positive tests. Hospitalisations, bed occupancy, intensive care admissions and deaths help show how severe a season is. Pharmacy sales of flu medicines and school absences can offer indirect signals.
The practical side of prevention also connects with access to care discussed in an earlier health report. The present issue is influenza tracking, not treatment.
People and animals move. Climate shifts and bird migration can change how viruses circulate. Surveillance systems can spot small changes earlier, but the data only help when they lead to prevention and response decisions.
Torres says every public health intervention needs an assessment before it starts and an evaluation afterwards. That keeps surveillance tied to action.
The indicators are working tools, not background figures. They show where the virus is circulating, which groups are affected and how much pressure reaches hospitals.
Health authorities can then adjust their response instead of following a fixed seasonal script. Spain's current activity is still below epidemic levels.
The evidence points to a practical conclusion. Influenza preparedness does not depend on a perfect prediction. It depends on an international network that can detect imperfect signals early.
Spain's low activity is no reason to stop watching. Variant tracking, hospital data and vaccine planning still have time to shape a measured response before the season's real burden becomes clear.
