Berlin. A spade against the flu every autumn - the flu vaccination is recommended for some of the population, but others can protect themselves with it if they want. The effect lasts for several months and protects for the season. Then the situation may look different again.
In contrast to other viruses, flu viruses change continuously. The vaccines are composed of the antigens of variants circulating worldwide. That's why manufacturers adapt their vaccines every year to the virus strains and variants that are likely to circulate in the coming flu season, as the Paul Ehrlich Institute (PEI), the Federal Institute for Vaccines, explains upon request.
The basis is therefore recommendations from the World Health Organization (WHO) and the Committee for Medicinal Products for Human Use at the European Medicines Agency. They look at variants of influenza viruses circulating worldwide. A forecast for the virus variants that will prevail in the following winter is usually made in February.
All three strains contained in the vaccines have been adapted for the 2026/2027 flu season. This is based on the changed antigenicity of the circulating viruses - i.e. the ability to detect the viruses through the antibodies formed after vaccination, explains the PEI. Significant antigenic differences were observed for the circulating viruses compared to the previous vaccine reference viruses.
The vaccine was adapted because all three strains have changed significantly in recent years, explains Leif-Erik Sander, director of the Clinic for Infectious Diseases and Intensive Care Medicine at the Charité - "with the aim of better adapting the vaccine to the circulating viruses."
“I wouldn’t primarily conclude from this that we’ll have a much stronger flu season,” said Sander. Many people came into contact with the still relatively new influenza variant, A(H3N2) of subclade K, last year. In addition, the flu vaccine has now been adapted to this. Last year there was a pronounced flu season with many sick people and full hospitals, but overall the season was not exceptionally difficult. “Even in the southern hemisphere, where winter is now coming to an end, there wasn’t such a severe flu season.”
The exact course of a flu season cannot be predicted in advance, says the PEI. The actual vaccination protection depends on how well the strain adaptation matches the virus strains actually circulating at the time. But the age of the vaccinated person and previous influenza infections or vaccinations also play a role. Vaccination protection wears off over time, so it also depends on the time of the flu infection. But less effective vaccines also prevent many cases of illness, and influenza illnesses are typically milder in vaccinated people.
Not necessarily. The following still applies: "The flu wave always comes, so you can basically set the clock accordingly. Many people die from it every year and it always leads to a high burden of disease," explains expert Sander. “But we don’t expect a particularly dramatic flu wave to hit us this year.”
The Standing Vaccination Commission (Stiko) recommends vaccinations against influenza for people aged 60 and over as well as people with previous illnesses, pregnant women and residents of care facilities. It is also recommended for children and adolescents with certain underlying illnesses. These include chronic respiratory diseases, cardiovascular, liver and kidney diseases, obesity and others. According to Stiko, the influenza vaccination rates among children and adolescents with underlying illnesses have been significantly too low for years.
According to the Robert Koch Institute (RKI), only 34.5 percent of people aged 60 and over were vaccinated against flu in the 2024/25 season, meaning more than half of this group had no vaccination protection. Sander emphasizes that the EU has a goal of a vaccination rate of 75 percent, but Germany is regularly well below that. “Adapting the vaccines is important, but above all we need a better vaccination rate.”
According to the RKI, the number of acute respiratory infections is currently at a moderate level and is primarily caused by cold viruses such as rhinoviruses and parainfluenza viruses as well as enteroviruses. The load of coronaviruses (SARS-CoV-2) measured in wastewater remains low, but there has been a slight increase in the last few weeks, according to the RKI weekly report on acute respiratory diseases. There is also a slight increase in influenza viruses.
