Respiratory viruses start circulating surprisingly early this year

While uncertainty remains regarding the public health impact of the upcoming influenza season, ECDC is preparing for the scenario that Europe could face a more severe influenza season than previously, especially if there is low vaccine uptake. A higher than usual number of infections would also add additional pressure on healthcare systems.

We are seeing influenza detections increasing much earlier than usual this year, and that means time is critical. 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,

says Edoardo Colzani, Head of Section Respiratory Viruses at ECDC.

We always stress the importance of vaccination and reported on Hungarians' lack of urgency in this matter a number of times:

As of week 46, 2025, the number of patients presenting to primary care with symptoms of respiratory illness, including influenza-like illness, were at baseline or low levels in all reporting countries. However, virological data shows an earlier than expected increasing trend, with a timing three to four weeks earlier than the two most recent seasons, and at the earliest range of five pre-COVID-19 pandemic seasons.

Test positivity in primary care surveillance, an indicator of transmission, is currently highest in children aged 5–14 years, which is typical at the start of seasonal activity.

The newly-emerged A(H3N2) subclade K (former J.2.4.1) has been now detected on all continents and accounts for a third of all A(H3N2) sequences deposited in the Global Initiative on Sharing All Influenza Data (GISAID) between May and November 2025 globally, and almost half in the EU/EEA.

A(H3N2) has not been the dominant virus in recent seasons which may lead to lowered immunity in populations without recent exposure, although serological data are not yet available to assess this further.

Even if a less well-matched A(H3N2) virus dominates this winter, the vaccine is still expected to provide protection against severe disease, so it remains a vital public health tool. It remains uncertain whether influenza A(H3N2) will dominate throughout the 2025/26 season or whether cocirculation with A(H1N1)pdm09 and/or B/Victoria will occur.

Read Portfolio's latest report on the 46th week in the current season of respiratory infections at the link below:

ECDC recommendations

• People at higher risk of severe disease should get vaccinated without delay.

  These groups include people over 65 years of age, pregnant people, people with underlying and chronic diseases or who are immunocompromised, and people living in closed settings such as long-term care facilities.
• Get vaccinated if you are a healthcare worker or work in a long-term care facility.
• Healthcare settings and long-term care facilities should strengthen their preparedness plans and infection, prevention and control measures as well as encourage staff and visitors to use face masks during periods of increased respiratory virus circulation.
• Healthcare providers should consider promptly administrating antivirals to patients at higher risk of severe disease to reduce complications.
• Healthcare providers should consider using antiviral prophylaxis during outbreaks in closed settings, e.g. long-term care facilities.
• Countries should promote clear, tailored communication on vaccination, hand hygiene and respiratory etiquette to help reduce transmission in the community.

Meanwhile, general practitioners in Hungary have also drawn attention to the spread of the 'Frankenstein variant' of the coronavirus. XFG is a recombination – a mixture of the two earlier virus sub-lines LF.7 and LP.8.1.2. Similar to Frankenstein's monster, which was assembled from different body parts, XFG combines parts of different virus lines. Experience shows that, although the symptoms of this latest version of the virus are not usually severe, they can sometimes cause serious complications.

The World Health Organization (WHO) and the European Centre for Disease Prevention and Control (ECDC) consider XFG a "variant under monitoring" (VUM), meaning health officials are watching it closely but do not yet consider it a cause for concern.

The WHO and the Robert Koch Institute (RKI) currently classify the risk from XFG as low.

Incidentally, there is no clear evidence as to whether the "razor blade sensation" in the throat actually occurs more frequently with XFG.

Symptoms such as severe sore throat and hoarseness are not specific to COVID-19 variants. They can also occur with other respiratory infections.

It is almost impossible to reliably distinguish between COVID-19 and, for example, the flu based on symptoms alone.

Public health risk of influenza for the EU/EEA population

In a typical season, influenza causes substantial morbidity in the European population,

with up to 50 million symptomatic cases and 15 000–70 000 deaths annually,

the ECDC said in its latest assessment.

All age groups are affected, although children have higher rates of illness and are usually the first to become sick and transmit the disease in their households, which can drive transmission in the community.

It is estimated that up to 20% of the population are contract influenza annually. This results in absence from school and work and a significant impact on healthcare systems, from primary to tertiary care, where patients with severe influenza or other complications can remain hospitalised for many days. Higher impact can be expected in closed settings such as LTCFs, where outbreaks of seasonal influenza can have high a morbidity and mortality.

Transmission rates fluctuate during the season, so the highest rates of hospitalisations and pressure to the healthcare system are expected for a limited number of weeks when circulation is high. Countries can implement effective pharmaceutical, public health and social measures during high virus circulation to mitigate this impact.

As in past influenza seasons,

the probability of infection for individuals in the general public is considered high.

However, for most individuals, influenza is usually a self-limiting illness, even asymptomatic for a significant percent (up to 60%), so the impact of influenza infection for individuals in the general population is estimated as low. Therefore, the risk posed to individuals in the general population in the current season is estimated as moderate based on currently available information.

The probability of infection is considered high for individuals at higher risk of severe disease.

The impact of severe influenza disease from A(H3N2) subclade K for individuals with chronic conditions is currently estimated as moderate. Persons older than 65 years of age, persons with underlying metabolic, pulmonary, cardiovascular, neuromuscular and other chronic diseases as well as immunocompromised and persons living in closed settings such as LTCFs are at higher risk for severe influenza and complications of their chronic conditions.

In addition, pregnant people are at increased risk of severe influenza disease, which can lead to severe complications for themselves and their babies.

Severe influenza leads to hospitalisation due to complications such as bronchitis, pneumonia and respiratory distress, or worsening of a chronic disease, and more rarely encephalitis and myocarditis. Hospitalisations in intensive care units (ICU) for severe influenza disease is associated with an estimated mortality, in one in four patients.

Cover image (for illustration purposes only): Getty Images