But none of the cases had a connection to countries with known clade 1b transmission, suggesting the rash-causing virus may be spreading undetected around the world.

Most of the cases identified have also been in gay and bisexual men, UKHSA officials said — which transmission of the strain hadn’t previously been observed in.

They have now urged all those eligible in the UK to get the mpox vaccine to thwart any potential spread of the virus across the country.

A different, less severe, form of mpox, called clade II, sparked alarm among health officials globally in 2022 when it began spreading rapidly across multiple countries mainly through sexual contact among gay and bisexual men.

However, new infections gradually tapered off amid boosted awareness of the disease and a hurried vaccination program.

At the time the UK reported almost