Spain Grapples with Unprecedented Flu Surge as Cases Double in a Week

Early and Aggressive Flu Season Grips Spain

Spain is currently facing an unusually early and intense influenza season, with national flu rates doubling in just one week and exceeding the peaks of the last three winters. Data released by the Carlos III Health Institute (ISCIII) indicates that the national incidence rate in primary care soared from 78.3 to 164.6 cases per 100,000 people in early December. This rapid acceleration has raised concerns among health authorities as the country heads into the Christmas holiday period, traditionally a time of increased transmission.

The current figures represent a significant departure from previous years, where the flu season typically peaked in late January or early February. Experts had warned earlier this month that the peak could coincide with the Christmas holidays, a prediction that now appears increasingly accurate.

Demographic and Regional Impact

The surge is disproportionately affecting younger populations, with children aged one to four years old experiencing the sharpest rise in incidence, climbing from 214 to 503 cases per 100,000. Children aged five to 19 are also heavily impacted. In Alicante province, children under 14, especially those under four, have seen rates as high as 4,031 cases per 100,000 inhabitants.

Several regions across Spain are reporting dramatic increases in flu activity:

• Madrid: Cases jumped by 145%, reaching over 275 cases per 100,000 residents.
• Catalonia: Incidence more than doubled to 418 cases per 100,000 people.
• Murcia: Experienced a 248% surge, with 180 cases per 100,000.
• Andalucia: Cases tripled in a week, reaching 33.5 per 100,000.
• Valencia: Rates more than doubled to 234 cases per 100,000.
• Alicante: Reached 1,192 cases per 100,000 in early December, surpassing last year's peak.

Strain on Healthcare System and Public Health Response

The rapid increase in flu cases is already putting pressure on Spain's healthcare system. Hospital admissions for influenza have almost doubled in a week, rising from 4 to 7.5 hospitalizations per 100,000 residents. Alarmingly, nearly one in five hospitalized flu patients has developed pneumonia, with ICU admissions at 4.4% and mortality at 4.6%. The positivity rate for flu tests in primary care centers has climbed to 41.6%, up from 26.8% a week prior.

The primary driver of this early surge is believed to be the circulation of the influenza A virus subclade K (H3N2), a variant characterized by higher transmission capacity. In response to the escalating situation, some regional governments have taken action. Catalonia and Murcia have reinstated mandatory mask-wearing in all health centers and care homes. Madrid is recommending masks in care homes, public transport, and crowded indoor spaces. Health authorities are urging the public to get vaccinated, use masks in high-risk settings, ensure proper ventilation, and practice good hand hygiene. Pharmacies have reported a 385% surge in mask purchases and a 150% rise in antigen test sales.

Broader Respiratory Infection Context

The flu surge is not occurring in isolation. Spain is also contending with other respiratory infections, including bronchiolitis in young children and ongoing, albeit low, levels of COVID-19. This combination has led to what some doctors are calling a 'three-virus winter,' similar to patterns observed in previous years across Europe. The country has already recorded an estimated 8,435 deaths from respiratory infections this season.