Twice the flu wave in Germany remained largely absent - now influenza is back, and relatively early. Quite high case numbers have been reported for several weeks. According to the definition of the Robert Koch Institute (RKI), the flu wave started in the last week of October. This is according to the weekly report on acute respiratory diseases on Wednesday evening.

Decisive for the assessment are results from a surveillance system in which samples of people with acute respiratory diseases are examined. Routinely, this looks for various pathogens, such as rhinoviruses, Sars-CoV-2 and influenza. The RKI explains the definition for the beginning of the wave as follows: "In a highly simplified way, one can say: if influenza viruses are actually detected in every fifth patient sample, the flu wave has begun."

"During the last few months, significantly more influenza reports were submitted to the RKI than in the pre-pandemic seasons around this time," the report continues. This is likely due in part to the recommendation since the Corona pandemic that respiratory symptoms should include testing for influenza viruses, it said. More than 2,100 cases of influenza have been reported so far this week - and a total of around 8,330 since the start of the season in October. A particularly large number of reports came from Bavaria and North Rhine-Westphalia, according to the report. There are also reports of 13 outbreaks with at least five cases, for example at schools and kindergartens.

In the years before Corona, the annual flu wave usually began in January and lasted three to four months, according to the RKI. In the past two seasons, however, the pandemic and the measures taken against it greatly changed the usual course: in 2020/21, the flu wave failed worldwide. And in 2021/22, there was no wave on the usual scale in Germany either, with the reporting figures only picking up somewhat after the Easter vacations and thus very late.

Even if there have been recent warnings of a now threatening severe wave: The RKI and other experts emphasize that the course cannot be predicted. However, according to the RKI, it is "conceivable" that the population is susceptible to the pathogens to an increased extent and/or an increased proportion of the population, as stated on the institute's website. Other experts had spoken of expected catch-up effects. That is, those who have not had a real flu for a while could now be due again.

Adults usually only get the disease every few years anyway, the Secretary General of the German Society for Immunology, Carsten Watzl, had recently said: "What is colloquially referred to as the flu is usually just a cold. With influenza, you can lie flat for a week." He said it's likely that more younger children than usual are without immune protection after the past two winters of low flu - they missed their first flu infections. In that group, however, the illness is usually not severe either, he said.

According to the RKI, the number of infections during a flu epidemic is estimated at five to 20 percent of the population, which corresponds to about four to 16 million people in Germany. Not every infected person falls ill. "The number of deaths can vary greatly in individual flu waves, from several hundred to more than 25,000 in the 2017/18 season," the RKI notes.

Flu vaccination is recommended in Germany for people over 60, pregnant women, the chronically ill, residents of retirement and nursing homes, and people at increased occupational risk, among others.

Image by Renate Köppel