Public health officials are to announce more UK monkeypox cases on Monday, as efforts ramp up to contain the first multinational outbreak of the virus that has led to cases in at least 14 countries.

The unusual outbreak of the rare disease has sparked a wave of contact tracing and testing, with the closest contacts of confirmed cases – such as partners and people in the same household – offered a vaccine and told to isolate at home for up to 21 days.

Under UK Health Security Agency (UKHSA) guidance, the same high-risk contacts are advised to avoid immunosuppressed people, pregnant women and children under 12, as they are more vulnerable to serious infections. Reports have said that one of the UK cases is a child who is in intensive care in London with the disease. The NHS and UKHSA said they would not discuss individual cases.

While some monkeypox patients have been admitted to hospital, many confirmed cases that do not need specialist care are told to isolate at home until local health protection teams are confident they are no longer infectious. “The vast majority of identified cases are isolating at home and do not require hospital admission,” said Dr Claire Dewsnap, president of the British Association for Sexual Health and HIV.

Monkeypox does not spread easily, and most people who become infected develop only mild symptoms, including fever, rash and blisters, which can clear up without treatment. But the virus can cause more serious illness in those with weakened immune systems, pregnant women and young children.Monkeypox does not spread easily, and most people who become infected develop only mild symptoms, including fever, rash and blisters, which can clear up without treatment. But the virus can cause more serious illness in those with weakened immune systems, pregnant women and young children.