This year in Berlin, mpox infections have doubled compared to the previous two years. So far, 186 cases have been reported, according to the State Office for Health and Social Affairs (Lageso). Almost all cases affected men (185). The median age was 35. About seven in ten people affected (71 percent) believe they contracted mpox through sexual contact with men.
Mpox is a rare disease and is transmitted through close physical contact, especially during sex. The risk of infection is greatest when in contact with the characteristic skin changes (blisters or crusts) seen in mpox patients. Droplet transmission is also possible, i.e., via saliva. The virus primarily causes a skin rash, but also fever and muscle pains. Germany first recorded cases in May 2022. There have been no deaths to date according to the RKI (Robert Koch Institute).
For men who have sex with men (MSM) and who frequently change sexual partners, the World Health Organization (WHO) estimates the risk of mpox infection as moderate. For other parts of the population, the risk is considered low.
First Case of Clade Ib in Berlin
The largest mpox outbreak in Berlin occurred in 2022. Back then, more than 1,600 lab-confirmed mpox cases were recorded. Since then, numbers have fallen significantly, with 68 cases in 2024 and 87 cases in 2023.
On Thursday, the Lageso announced that Berlin had, for the first time, a mpox case of the Clade Ib variant. Until now, Berlin had only cases of Clade II. The man was between 35 and 40 years old and developed fever, the characteristic skin rash, and swollen lymph nodes on December 8. The patient was not vaccinated against mpox, according to authorities. The relevant health department ordered home isolation. The man likely contracted the infection abroad in Europe and reported sexual contact with men as the probable route of infection.
No Indication of a More Severe Disease Course
In Germany, since October 2024, 16 cases of Clade Ib have been reported to the Robert Koch Institute (RKI), including 9 this year, Berlin’s case among them. Some experts suggest that Clade I may, on average, lead to more severe disease than Clade II. The Lageso explains: “Currently there are no indications that mpox infections with Clade 1b, which has appeared in Europe, are associated with increased transmission potential or greater disease severity.” The RKI also does not expect Germany to be at higher risk.
Transmission Mainly Through Sex
Vaccination against mpox is recommended for certain groups in Germany. These include men who have sex with men (MSM) and frequently change partners, as well as sex workers. For a basic immunization, two doses are required. The vaccination has been available since summer 2022.
The share of infected individuals without protection was markedly higher in Berlin this year than in previous years, explains infection epidemiologist Claudia Ruscher. She is the acting head of the Surveillance and Epidemiology of Infectious Diseases division at Lageso. 44 percent of infections were not vaccinated this year. In 2024, 32 percent had no vaccination, and 2023 was 29 percent.
There are several explanations for this development, says Ruscher. On the one hand, there may be groups that vaccination campaigns do not reach well. On the other hand, Berlin has a large and international MSM community—men who have sex with men. Every year, new people move to the capital, bringing new potential at-risk individuals who were previously not reached.
Berlin Has the Most Cases Nationwide
“Berlin has a very permissive and sex-positive scene. That creates a lot of transmission potential,” says the infection epidemiologist. There are many large events and many places where people can have sex anonymously. All of this are reasons why Berlin has the most mpox cases in the nationwide comparison. “It would be good if, before major international events, especially during Pride Month, there was proactive education about vaccination.”
Expert: The Disease Must Be Kept in View
Compared with other infectious diseases, mpox cases are rare. Why is it still important to keep an eye on the pathogen? Mpox remains a relatively new disease, about which there is little data on the severity or the course of illness, explains Ruscher. Even if there are only a few cases, it is essential to monitor the pathogen. If the virus changes, if other population groups become infected, or if transmissibility changes, it is important to detect it.
