In 2025, the flu season started several weeks earlier, and the new variant of the virus raises concerns among doctors. We explain why experts advise getting vaccinated quickly and what measures can significantly enhance your protection.
This year, a new variant of the H3N2 virus, subclade K, is causing particularly significant headaches for doctors and the public.
Initial studies of current illness rates show that the new subtype spreads significantly more easily than previously known strains of the flu. Therefore, experts expect that the number of cases will be approximately 20 percent higher than during a typical flu epidemic.
Additionally, the timing is noteworthy: the 2025 flu season is starting unusually early. According to the publication Ärzte-Zeitung, it will begin about three to four weeks earlier than in the last two years.
This trend is also evident beyond Germany. Experts from several countries are warning of an early and potentially intense flu epidemic, which is currently causing concern across Europe.
According to Jim Mackey, head of the National Health Service in the UK: "There is no doubt that this winter will be one of the toughest our staff have ever faced."
Symptoms Similar to COVID
Typical symptoms of the new H3N2 variant include a sudden rise in temperature, which can range from moderate to high and is often accompanied by severe malaise.
Many patients also report pronounced aches and pains in the body, which is particularly characteristic of this variant. Since some symptoms resemble those of COVID-19, doctors recommend timely testing for an accurate diagnosis.
Chills with H3N2 often intensify in combination with other symptoms. Additionally, there is sometimes an intense, prolonged cough, which is also known from other strains of the flu.
What Lies Behind This?
The heightened attention to the current flu season is also linked to international events.
For example, in Australia, the new subclade has led to an exceptionally severe flu epidemic, with over 400,000 laboratory-confirmed cases reported. This is the highest figure on record. Many experts view this experience as a possible indication that the virus could affect the Northern Hemisphere as well.
The high transmissibility of this variant is explained by significant changes within subclade K. According to virologist Ulrike Protzer from the Technical University of Munich, these deviations complicate the immune system's recognition of the virus.
"Our immune response simply does not recognize the virus as well and therefore does not fight it as effectively," she explains.
Despite the large number of cases, there is an important clarification: to date, there is no evidence that subclade K is more dangerous or causes a more severe course of illness than other flu strains.
Virologist Florian Krammer from the Medical University of Vienna emphasizes in Deutsches Ärzteblatt: "Yes, early activity may indicate the start of the flu season. But, as I said, in most European countries it is just beginning, and it is difficult to predict how it will develop."
Who Is Particularly at Risk?
As with any other flu, infection with the new variant can lead to a severe course of the disease.
Particular risk groups include the elderly and individuals with pre-existing conditions. For these groups, the upcoming flu epidemic poses an increased risk.
Experts are especially closely monitoring the possibility of co-infection - seasonal flu and the H5N1 avian flu virus.
There is a risk that the viruses could exchange genetic segments, potentially leading to the emergence of new variants that could be transmitted from person to person.
This risk is higher in winter, as both types of viruses circulate more frequently during this time.
Vaccination Provides Protection
Vaccination remains the best form of protection - even if the existing vaccines are not entirely suitable for the currently circulating viruses. Experts believe that the emergence of a new type of virus does not mean that vaccination will become less effective.
Initial data from the UK has already confirmed good protection. Moreover, vaccines can significantly mitigate the severe course of the disease, even if they do not precisely match the dominant strain. Vaccination protects not only against H3N2 but also against H1N1 and influenza B.
Therefore, the European Centre for Disease Prevention and Control urged at-risk individuals last week to get vaccinated as soon as possible.
According to the recommendations of the Standing Committee on Vaccination, this advice remains particularly relevant for individuals over 60, those with chronic illnesses, pregnant women, residents of nursing homes, and healthcare personnel.
