Mpox is a serious infectious disease that can present itself in the form of painful skin lesions, these can appear on any part of the body.

Mpox is a rare infection most commonly found in central and east Africa. The infection can be caught from:

• any close physical contact with mpox blisters or scabs (including during sexual contact, kissing, cuddling or holding hands)
• touching clothing, bedding or towels used by someone with mpox
• contact with bodily fluids such as saliva, snot or mucous

Mpox is usually mild and can get better within a few weeks without treatment. But, if your symptoms are more severe and you become unwell, you will need treatment in hospital.

The risk of needing treatment in hospital is higher for:

• pregnant women
• young children
• people with a condition or who are taking a medicine that affects their immune system

The mpox (MVA) vaccination

You are being offered a vaccination to help protect you against mpox. The MVA vaccine helps prevent or reduce the severity of mpox (and smallpox) infection.

The vaccine is manufactured in Europe by Bavarian Nordic. When you are given the vaccine, your immune system (the body’s natural defence system) produces antibodies against the mpox virus.

Note: The vaccine you are being given is called Imvanex in the UK and Europe, Jynneos in the US and Imvamune in Canada. These all contain the same MVA vaccine and are made by the same company.

The MVA vaccine does not contain smallpox or mpox virus and cannot spread or cause smallpox or mpox.

Imvanex vaccine has been authorised by the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) to protect against smallpox and mpox.

The UK Health Security Agency (UKHSA) and the Joint Committee on Vaccination and Immunisation (JCVI) recommends the use of MVA vaccine as part of the response to cases of mpox.

Who should have the MVA vaccine

UKHSA currently recommends that MVA is offered to:

• healthcare workers who are caring for and who are due to start caring for a patient with confirmed mpox
• gay, bisexual and other men who have sex with men (your clinician will advise vaccination for you if you have multiple partners, participate in group sex or attend ‘sex on premises’ venues)
• people who have already had close contact with a patient with confirmed mpox -vaccination with a single dose of vaccine should be offered as soon as possible (ideally within 4 days but sometimes up to 14 days)
• people who are members of a group or attend a setting where there is a case or cluster, or where some of the members have had close contact with a case

Does the vaccine work?

Two doses of vaccine have been shown to give a high level of protection against mpox. Protection is also very good after the first dose, but a second dose is sometimes advised for long term protection.

The vaccine may not completely prevent infection but even if you catch mpox, the symptoms should not be as bad.

The vaccine also takes time to work. It might start to work after a few days and should reach the highest protection by about 4 weeks after the first dose.

The second dose can be given after 28 days but can be given much later, even after a few months. A longer time between the first and second doses should improve your long term protection.

Even after 2 doses you should continue to be aware of the risks and symptoms of mpox. If you develop symptoms, stay at home and call 111 or a sexual health clinic.

How MVA is given

There are two methods used to give the MVA injection. One method injects below the skin or into the muscle (similar to most other vaccines), the other one injects into the skin, like the BCG vaccine against TB. This second method is only used when several people are being vaccinated in the same session. Both methods are highly effective.

Side effects of MVA vaccine

The vaccine has a very good safety profile. Like all medicines and vaccines it can cause side effects, but most of these are mild and short-lived and not everyone gets them. Unlike the old smallpox vaccine, vaccination does not leave a scar.

Side effects may be more common in people who have previously received a dose of live smallpox vaccine. These people only need a single dose of MVA to boost their existing protection.

You should tell the doctor or nurse if you have received smallpox vaccination in the past or if you have atopic dermatitis, as the risk of side effects from the MVA vaccine may be higher.

If you are HIV positive or have any other condition or treatment leading to a weakened immune system, the vaccine may not protect you as well. Let your doctor or nurse know. If you have a history of keloid scars you should tell the doctor or nurse, as this affects the way the vaccine should be injected.

Common side effects

Common side effects include pain and itching at the injection site and headache, muscle ache, sickness and tiredness. About 1 in 10 people will have chills and fever, but these should not last more than a few days.

If you experience any of the side effects listed above, you should rest and you can take the correct dose of paracetamol to help relieve the symptoms.

If you already have atopic dermatitis (a form of eczema), you may experience more intense local skin reactions (such as redness, swelling and itching) and other general symptoms (such as headache, muscle pain, feeling sick or tired), as well as a flare-up or worsening of your skin condition.

Serious side effects

Some other conditions have been more rarely reported in people who received the vaccine. In the spirit of openness, the vaccine product insert mentions all these conditions – even those reported from single cases – but this does not mean that the vaccine was responsible. If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet.

By reporting side effects you can help provide more information on the safety of this vaccine.

If you have the following symptoms shortly after vaccination, ring 999 (or ask someone to do this for you):

• difficult or noisy breathing or wheezing
• swollen tongue
• prolonged fainting or unconsciousness
• confusion

These symptoms may be a sign of a rare but serious allergic reaction and typically happen within 15 minutes of vaccination. Simple faints are much more common after vaccination. If you do faint, stay flat on your back with your legs raised. If this doesn’t make you feel better, then call for help.

For other symptoms, contact 111 or your health professional.

Reporting side effects

Please report any suspected side effects:

• online at Yellow Card Scheme
• downloading and using the Yellow Card app:
  • Apple
  • Android
• calling the Yellow Card scheme on 0800 731 6789 (9am to 5pm)

By reporting side effects you can help provide more information on the safety of this vaccine.

Vaccinating children with MVA

Mpox is known to be more serious in young children than in older children and adults. Therefore the vaccine is still recommended in children, even in babies.

Vaccines using the MVA virus seem to work very well and have an acceptable safety record in small children, with side effects similar to other baby vaccines. The MVA-BN vaccine has also been given safely to a number of children in the UK after contact with a person with mpox.

Having the MVA vaccine while pregnant

If you are pregnant, or think you may be pregnant or are planning to have a baby, talk to your doctor. The virus in the vaccine does not grow and multiply in the human body and so cannot spread to an unborn child.

Mpox may be more severe in pregnancy and you also need to consider the risk of passing infection to your baby. The doctor should help you to understand the benefits and how this balances against any theoretical risk from the vaccine.

Having the MVA vaccine while breastfeeding

If you are breast feeding, you will still be offered the vaccine. The virus in the vaccine does not grow well in the human body and so cannot spread to the breastfed child. If you catch mpox, however, you could pass infection to your baby, and mpox may be more severe in small babies. The doctor can help to explain the benefits.

Those who should not receive the MVA vaccine

The only people who cannot receive the vaccine are those who suffered a sudden life-threatening allergic reaction to a previous dose of the vaccine, or any ingredient of vaccine before. The vaccine contains trace amounts of chicken protein, benzonase and gentamicin and ciprofloxacin (antibiotics).

Further information

You will get more information on this medicine from the package insert that the doctor or nurse should give you. The insert is also available on the European Medicines Agency website.