Mpox vaccine in the UK: who is offered it and what to expect

Mpox is a viral infection that causes a rash and flu-like illness. The NHS says there have been a small number of UK cases since 2022, mostly Clade 2 mpox with a very small number of Clade 1 cases, and that the risk of catching it in the UK is low for most people. The vaccine is therefore targeted, not universal.

The virus spreads through close physical contact with the rash, blisters or scabs (including during sex, kissing or cuddling), through contaminated clothing, bedding or towels, and through the coughs and sneezes of someone close by. In parts of central and east Africa it can also pass from infected animals, usually rodents.

The recommendation is built around exposure, not identity. The NHS names men who have sex with men and who have multiple partners, take part in group sex or attend sex-on-premises venues. It also lists people who work at such venues, such as cleaning staff, and anyone who has had or will have close contact with a person who has mpox or who is at high risk of exposure.

If you are a close contact of a confirmed case, the local health protection team should get in touch and tell you where to be vaccinated. People who think they qualify are asked to ring a sexual health clinic first and not to turn up unannounced, so staff can check eligibility.

There is one mpox vaccine in use in the UK, and the patient leaflet is on the electronic Medicines Compendium. It is given by injection, usually into the upper arm. Most people are offered two doses at least 28 days apart.

The NHS says an extra dose may be offered to people with a severely weakened immune system once two years have passed since vaccination, and to healthcare workers after ten years. It can be given on the same day as other vaccines commonly offered in sexual health clinics, including those for hepatitis A, hepatitis B, HPV and the MenB vaccine used against gonorrhoea.

After two doses the vaccine provides around 80 per cent protection according to the NHS, so some risk remains. If infection occurs after vaccination, symptoms are usually milder. Most people need only the two doses for long-term protection.

It follows that vaccination does not replace common-sense precautions. The NHS advice includes watching for symptoms for three weeks after returning from an area with mpox, talking to sexual partners about symptoms, and pausing sex and intimate contact if you have symptoms until a doctor says you can no longer pass it on.

The vaccine is not given to anyone who has had anaphylaxis after a previous dose or who is allergic to an ingredient, which the NHS lists as including chicken protein, benzonase, gentamicin and ciprofloxacin. Otherwise most people can have it, including during pregnancy or breastfeeding.

Common reactions are itching, pain, hardness, swelling or warmth at the injection site, headache, fever or chills, tiredness, aches and reduced appetite, and they normally clear within a few days. Some people develop a small mark or firm lump where the needle went in that can last for months. Severe allergic reactions are very rare and happen within minutes, which is why vaccinators are trained to treat them straight away.

Symptoms usually start between 5 and 21 days after infection, with fever, headache, muscle and back ache, swollen glands and exhaustion, followed one to five days later by a rash that can affect the hands, feet, mouth, genitals and anus. Anal pain or bleeding can occur.

The NHS asks people with a blistering rash who have had new sexual partners, or contact with a possible case, to call a sexual health clinic before visiting and to stay at home meanwhile. Those with a rash after travel to an area with mpox should call NHS 111. Mpox is usually mild and resolves within a few weeks, but hospital care may be needed, with older people, young children and people with weakened immunity at higher risk.