Why has Spain entered flu season with infection rates already at epidemic level before winter has even begun? That’s the question troubling health officials this week, as a sharp rise in respiratory illnesses pushes the country into its earliest widespread outbreak in years.

New data from the Carlos III Health Institute show a rapid jump in flu diagnoses between 17 and 23 November, reaching an average of 112.2 cases per 100,000 people. Twelve months ago, that figure barely reached 13. Such an early spike is unusual, and doctors warn it may signal a difficult season ahead.

Spain’s pattern this year mirrors a wider European trend: respiratory infections are circulating earlier, faster, and among younger age groups. Primary care centres recorded 519.3 cases of respiratory illness per 100,000 inhabitants, reflecting a steady rise not just in flu but also in other seasonal viruses.

RSV – long a major contributor to winter hospital admissions among infants – is also climbing. Yet the increase is far milder than in pre-vaccination years.

Young children driving the flu wave

The flu’s impact is falling heaviest on the very young. Children aged 1 to 4 have the highest recorded rates, with 428.5 cases per 100,000. School-aged children and infants under one follow closely.

Paediatricians say this pattern is predictable. Classrooms, nurseries and close-contact environments allow flu to move quickly through groups who have limited prior immunity. Children then transmit the virus into households, accelerating wider community spread.

Recognising symptoms in a crowded winter virus season

The early start to the season is making diagnosis trickier for both families and clinicians. Most cases involve:

• Cough

• Fever

• Fatigue and general discomfort

• Nasal congestion

These overlap with RSV and Covid-19, meaning no single symptom reliably identifies the flu. Doctors continue to advise staying home when unwell, particularly around vulnerable people.

Hospitals steady despite rising infections

So far, Spain’s hospitals are not under strain. Since October, more than 33,000 people have required admission for flu-related complications, but the current hospitalisation rate remains stable at 2.6 per 100,000 inhabitants.

RSV admissions have risen slightly – from 0.5 to 0.8 per 100,000 – though bronchiolitis cases have dropped compared with previous years. Health experts attribute this improvement to newborn vaccination programmes introduced nationwide.

Covid-19 continues its decline

Amid the surge in flu, one respiratory virus is moving in the opposite direction. Covid-19 cases in primary care have fallen from 10.6 to 4.2 per 100,000, while hospital figures remain unchanged.

Clinicians note that Covid symptoms this season typically involve sore throat, cough and fatigue rather than high fever, helping distinguish it from other infections.

What lies ahead this winter?

With flu circulating earlier than expected, health authorities anticipate a further rise in infections through December. Vaccination rates remain lower than ideal in older adults and people with chronic illnesses – two groups most at risk of complications.

Officials are urging anyone eligible for the seasonal jab to come forward, warning that early circulation may coincide with peak December gatherings, increasing the risk of transmission.

Spain faces a long flu season unless vaccination picks up

This year’s unusually early wave suggests the flu season may stretch well into the new year. With hospitals currently stable but infections climbing fast among children, public health experts argue that strengthening vaccination coverage is the most effective tool to prevent pressure on the healthcare system as winter progresses.

Source: El Confidencial