A new Norovirus variant, GII.17, is causing an unusually early and strong rise in infection numbers in Germany. By mid-November 2025, the Robert Koch Institute reports 5396 confirmed cases, compared to 4107 the previous year. Experts warn of a big season and emphasize the importance of hygiene measures.
The Norovirus season 2025 has started unusually early in Germany and is progressing more intensely than in previous years. Typically, it peaks in the winter months, but increased activity is already evident, especially in communal facilities like daycares, schools, nursing homes, and hospitals. The Robert Koch Institute (RKI) records 5396 infections by mid-November, a clear increase from the 4107 cases the previous year. Similar trends are reported in other European countries and the USA.
A key factor is the GII.17 variant, which has been prominent worldwide since 2024. "When new strains appear, more people are susceptible, and the number of illnesses rises," explains virologist Lee-Ann Jaykus from North Carolina State University. New strains emerge roughly every seven to ten years, with low immunity in the population against them. Epidemiologist Ben Lopman from Emory University tells "Newsweek" of signs for a "big Norovirus season," as activity is unusually high for the time of year.
Noroviruses are extremely contagious: Just 10 to 100 particles can cause an infection. They spread via hands, surfaces, or food and withstand temperatures from minus 20 to plus 60 degrees. Symptoms include sudden vomiting, diarrhea, abdominal cramps, nausea, headaches, and mild fever; they last 12 to 48 hours. Children under five and those over 65 are particularly at risk, as dehydration can occur.
There is no vaccine or specific therapy. The RKI recommends thorough handwashing, surface disinfection, washing fruits and vegetables, and avoiding raw shellfish. Infected individuals remain contagious for at least 48 hours after symptoms subside, with the virus shed longer.
