According to the risk assessment published on the ECDC website, compared to previous years, cases are appearing three to four weeks earlier and circulation is being driven by a new strain of influenza A (H3N2), subtype K.

Although there is still uncertainty about the impact of the next flu season on public health, the ECDC says that authorities should prepare for the scenario of "a more severe flu season" in Europe, especially if there is low vaccination uptake.

An above-normal number of infections would also increase pressure on health systems, warns the ECDC.

“We are seeing a surge in flu cases much earlier than normal this year, and that means time is crucial,” says the head of the ECDC’s Respiratory Virus Section, Edoardo Colzani, appealing: “If you are eligible for vaccination, please don’t wait. Getting vaccinated now is one of the most effective ways to protect yourself and those around you from serious illness this winter.”

The ECDC insists that people at higher risk of developing serious illness should get vaccinated without delay.

These groups include people over 65, pregnant women, people with pre-existing and chronic illnesses or who are immunocompromised, and people living in enclosed settings such as long-term care facilities and nursing homes.

It also recommends vaccination for healthcare professionals or workers in long-term care facilities.

It advises healthcare services and long-term care facilities to strengthen their preparedness plans and infection prevention and control measures, and to encourage staff and visitors to wear masks during periods of increased respiratory virus circulation. The ECDC also argues that healthcare professionals should consider the immediate administration of antivirals to patients at higher risk of developing severe illness to reduce complications.

Healthcare professionals should also consider the use of antiviral prophylaxis during outbreaks in closed settings, such as long-term care facilities or residences.

It also calls on countries to promote “clear and personalized communication” about vaccination, hand hygiene, and respiratory etiquette to help reduce community transmission.

According to the ECDC, in a typical season, influenza causes substantial morbidity in the European population, with up to 50 million symptomatic cases and 15,000 to 70,000 deaths per year.

Portugal recorded 1,609 excess deaths during the influenza epidemic from December 2024 to January 2025, a period coinciding with the influenza epidemic and extreme temperatures, mainly affecting women and people over 85 years of age.

The Centers for Disease Control warns that all age groups are affected, although children have higher rates of illness and are often the first to become ill and spread the disease in their homes, which can drive community transmission.

It is estimated that up to 20% of the population contracts influenza annually, resulting in school and work absences and a “significant impact” on health systems, warns the Centers for Disease Control, noting that the impact is greater in closed settings such as long-term care facilities.