Contacts of monkeypox cases at high risk of having caught the infection should self-isolate for 21 days, latest government guidance says.

The UK Health Security Agency (UKHSA) guidance now recommends that people who have had “unprotected direct contact or high-risk environmental contact” should isolate for three weeks.

This includes no travel, providing details for contact tracing and avoiding direct contact with immunosuppressed people, pregnant women and children under 12.

Those who are considered at high risk of having caught monkeypox may have had household contact, sexual contact, or have changed an infected person’s bedding without wearing appropriate PPE.

UKHSA also advises that they are offered a smallpox vaccine.

The guidance comes after Dr Susan Hopkins, chief medical adviser for UKHSA, warned that monkeypox is spreading through community transmission.

So far the agency has confirmed 20 cases in the UK.

Dr Hopkins said updated figures for the weekend will be given on Monday as she warned of more cases “on a daily basis”.

The disease, first found in monkeys, can be transmitted from person to person through close physical contact, including sexual intercourse, and is caused by the monkeypox virus.

Dr Hopkins warned that doctors are seeing community transmission, with cases predominantly being identified in individuals who self-identify as gay or bisexual or men who have sex with other men.

Speaking to BBC One’s Sunday Morning, Dr Hopkins said: “We will be releasing updated numbers tomorrow – over-the-weekend figures.

“We are detecting more cases on a daily basis and I’d like to thank all of those people who are coming forward for testing to sexual health clinics, to the GPs and emergency department.”

Asked if there is community transmission in the UK, she said: “Absolutely, we are finding cases that have no identified contact with an individual from west Africa, which is what we’ve seen previously in this country.

“The community transmission is largely centred in urban areas and we are predominantly seeing it in individuals who self-identify as gay or bisexual, or other men who have sex with men.”

Asked why it is being found in that demographic, she said: “That’s because of the frequent close contacts they may have.

“We would recommend to anyone who is having changes in sex partners regularly, or having close contact with individuals that they don’t know, to come forward if they develop a rash.”

Asked if people will need to to be vaccinated, she said: “There is no direct vaccine for monkeypox but we are using a form of smallpox vaccine – a third-generation, smallpox vaccine that is safe in individuals who are contacts of cases.

“So we’re not using it in the general population.

“We’re using it in individuals who we believe are at high risk of developing symptoms, and using it early, particularly within four or five days of the case developing symptoms.

“For contacts, (this) reduces your risk of developing disease, so that’s how we’re focusing our vaccination efforts at this point.”

It comes as US president Joe Biden said that recent cases of monkeypox which have been identified in Europe and the United States are something “to be concerned about”.

In his first public comments on the disease, Mr Biden added: “It is a concern in that if it were to spread it would be consequential.”