Tens of thousands of gay and bisexual men at higher risk of being exposed to monkeypox should be offered vaccines to help control the recent outbreak of the virus, health officials have said.

Here are your questions answered about who will get the jab, which vaccine it will be and when they are expected to get it.

– Who will be offered the jab?

Some gay and bisexual men at higher risk of exposure to monkeypox should be offered the smallpox vaccine Imvanex, the UK Health Security Agency (UKHSA) has said.

– But why are they being offered a smallpox jab?

Smallpox is in the same virus “family” as monkeypox. There is currently no vaccine licensed in the UK or Europe for immunisation against monkeypox.

As monkeypox is related to the virus which causes smallpox, vaccines developed for smallpox are considered to provide “cross-protection” against monkeypox.

The UKHSA said the smallpox vaccine “is shown to be effective against monkeypox”.

– So will everyone get the vaccine?

No. Officials have said the vaccine should not be offered to everyone.

It will only be offered to certain gay and bisexual men.

Eligibility criteria is likely to depend on a person’s sexual activity.

The UKHSA guidance states that a medic may advise vaccination for someone who “has multiple partners, participates in group sex or attends ‘sex on premises’ venues”.

– I thought it was already being offered to some people?

It is, some healthcare workers caring for people with the virus have been offered the jab. As have close contacts of confirmed cases, to reduce their risk of symptoms and severe illness.

– What’s the latest in the UK?

Between May 6 and June 20, 793 cases of monkeypox have been confirmed in the UK.

Of these, 18 were in Scotland, three were in Northern Ireland, six were in Wales and 766 were in England. Just five cases have been confirmed among women.

The majority of cases are among people in London but cases have been found in other regions too.

– How do I know if I have it?

Symptoms include new and unusual spots, ulcers or blisters anywhere on the body; fever; headaches; muscle aches; chills; fatigue and swollen glands.

Most people have a mild illness, with recovery within three weeks. But in some cases, severe illness can occur and sometimes results in death.

– When will people be able to get the vaccine?

Details are still forthcoming but the UKHSA said that NHS England will set out details “shortly”.

– Is monkeypox a sexually transmitted infection?

The virus is not currently defined as a sexually transmitted infection, but it can be passed on by close and intimate contact that occurs during sex.

Spread of monkeypox can occur when a person comes into close contact with an infected animal or an infected human.

The stages of monkeypoxThe stages of monkeypox (UK Health Security Agency/PA)

It may also occur when a person comes into close contact with material contaminated with the virus such as bedding.

Anyone can get monkeypox but the latest cases have been mainly linked to “sexual networks of gay, bisexual and other men who have sex with men”, the UKHSA said.

– Why is this outbreak happening?

One theory behind the latest outbreak could be that there is waning immunity to smallpox among people under the age of 50.

Vaccines for smallpox have not been routinely administered from around the time of the eradication of the disease in 1980, which could mean that younger people who did not get the vaccine do not carry the protection afforded by the smallpox jab.