ECDC Confirms 2025/26 Flu Vaccination Effective Amidst Virus Drift Concerns

Vaccine Effectiveness Confirmed Despite Virus Drift

The European Centre for Disease Prevention and Control (ECDC) has affirmed the effectiveness of the 2025/26 seasonal influenza vaccination, providing reassurance amidst concerns over a drifted influenza A(H3N2) subclade K virus. This season has seen an earlier onset of influenza activity across the EU/EEA, largely driven by the rapid circulation of this new subclade.

The A(H3N2) subclade K virus exhibits genetic changes, specifically mutations in its hemagglutinin gene, leading to its characterization as 'antigenically drifted' compared to the vaccine strain. Despite this drift, preliminary data from the Vaccine Effectiveness, Burden and Impact Studies (VEBIS) primary care multicentre study in the EU/EEA suggest that the seasonal vaccines are providing protection against influenza A(H3N2) infection.

Preliminary Effectiveness Data and Public Health Recommendations

Early estimates of vaccine effectiveness against influenza A(H3N2) infection range from 52% for individuals aged 0-17 years and 57% for those aged 18-64 years in the EU/EEA. Furthermore, initial data from England indicate effectiveness against hospital attendance of 70-75% for children aged 2-17 years and 30-40% for adults. Experts emphasize that the primary goal of vaccination is to prevent severe disease, and effectiveness against severe outcomes is expected to be maintained.

The ECDC continues to recommend seasonal influenza vaccination, particularly for vulnerable groups. The 2025/26 seasonal flu vaccines are trivalent, designed to protect against three main seasonal influenza viruses: an A(H1N1) virus, an A(H3N2) virus, and a B/Victoria lineage virus. The B/Yamagata lineage is no longer included in vaccine formulations.

Germany's Vaccination Efforts and Challenges

In Germany, the Paul-Ehrlich-Institut (PEI) reported the release of over 18 million doses of influenza vaccine for the 2025/2026 season by mid-October 2025, ensuring adequate supply for doctors' offices and pharmacies. The Standing Commission on Vaccination (STIKO) in Germany advises annual flu vaccination, especially for high-risk groups such as the elderly, pregnant women, and individuals with chronic diseases. For those aged 60 and over, STIKO specifically recommends high-dose vaccines and those with an adjuvant.

However, vaccination rates in Germany remain a public health concern. Recent interim data from the Robert Koch Institute (RKI) for the 2024-25 season showed that flu vaccination coverage among German adults aged 60 and older declined to 34.5%, marking its lowest level in over 17 years. This falls significantly short of the 75% target for at-risk populations set by the World Health Organization (WHO) and the European Union.

Evolving Symptoms and Season Characteristics

The 2025 flu season is characterized by a high severity classification and unusual patterns of influenza spread. While typical flu symptoms persist, additional or atypical symptoms are being reported more frequently, particularly in early infection or milder cases. These include:

• Extreme fatigue or exhaustion beyond typical muscle aches
• Gastrointestinal symptoms such as nausea, vomiting, and diarrhea
• A strong feeling of 'foggy' brain or cognitive slowness
• Higher incidence of rapid worsening after initially mild symptoms

Public health authorities continue to monitor the situation closely and urge individuals, especially those in high-risk categories, to get vaccinated to mitigate the impact of the ongoing influenza season.