Monkeypox infections are steadily increasing in Great Britain. “We are discovering more cases every day,” UKHSA senior medical adviser Susan Hopkins told the BBC on Sunday. According to her, the rare viral disease is now spreading in Great Britain without being connected to West or Central Africa, where it is native.

According to Education Minister Nadhim Zahawi, the British government has already started buying up stocks of smallpox vaccine. “We take it very, very seriously,” he told the BBC.

Great Britain had reported 20 cases by Friday, and Hopkins has now announced a new balance sheet for Monday with the numbers from the weekend. There are “new” cases every day, she said. Most infected adults have “relatively mild” symptoms. She initially did not want to confirm reports that an affected person had to be treated in the intensive care unit.

Monkeypox cases have been detected in several European and North American countries since early May. Symptoms include fever, headache, muscle aches, and a rash that often starts on the face and then spreads to other parts of the body. Most people recover within several weeks.