Tens of thousands of men are to be offered a vaccine in a bid to stem the monkeypox outbreak in the UK, health officials have said.
Some 793 cases have been confirmed in the UK.
The current outbreak has largely occurred among gay and bisexual men, according to the UKHSA.
Just five cases have been confirmed in women.
The UK Health Security Agency (UKHSA) said that the jab had been shown to be effective against monkeypox.
Who will be offered vaccine in wider rollout?
The UKHSA said that in a bid to control the outbreak, some gay and bisexual men at higher risk of exposure to monkeypox should be offered the smallpox vaccine Imvanex.
Its new strategy, endorsed by the Joint Committee on Vaccination and Immunisation (JCVI), suggests that eligibility would depend on a number of factors but a clinician may advise vaccination for someone who has a “recent history of multiple partners, participating in group sex, attending sex on premises venues or a proxy marker such as recent bacterial STI in the past year”.
The guidance does not recommend vaccination to the general population.
A number of health workers are already offered the jab, including those who care for people with the virus and lab workers where pox viruses are handled.
The vaccine has also been offered to close contacts of those who have a confirmed case of monkeypox to reduce their risk of symptoms and severe illness.
How can people get the vaccine?
The NHS in England is to set out details on how eligible people can get vaccinated “shortly”.
People are advised not to come forward for the vaccine until contacted.
What have health officials said?
Dr Mary Ramsay, head of immunisation at UKHSA, said: “Our extensive contact tracing work has helped to limit the spread of the monkeypox virus, but we are continuing to see a notable proportion of cases in gay, bisexual and other men who have sex with men.
“By expanding the vaccine offer to those at higher risk, we hope to break chains of transmission and help contain the outbreak.
“Although most cases are mild, severe illness can occur in some people, so it is important we use the available vaccine to target groups where spread is ongoing.
“In the meantime, everyone should continue to be alert to any new spots, ulcers or blisters on any part of their body, particularly if they’ve had close contact with a new partner.
“If you think you have these symptoms, avoid close contact with others and call NHS 111 or your local sexual health centre, though please phone ahead before attending.”
Alex Sparrowhawk, health promotion specialist at the Terrence Higgins Trust, added: “This targeted vaccination programme is a positive move forward while the data still shows monkeypox is disproportionately affecting gay and bisexual men in the UK.
“We encourage everyone, regardless of your sexuality, to be vigilant about new spots, ulcers and blisters, and are continuing to closely monitor the latest data in order to play our part in providing the latest guidance and health information on monkeypox to empower the communities most affected to best protect their health.”
Robbie de Santos, director of communications and external affairs at Stonewall, said: “While we know anyone can catch monkeypox, we welcome the vaccine being offered to those gay and bi men who are eligible, who are currently at a higher risk of getting the virus.
“It is important that gay and bi men get the vaccine when offered to protect themselves and others. Let’s help get the outbreak under control so we can all have a safe and happy pride season.”