Mpox vaccine - Safety and effectiveness
The MVA vaccine is safe. It meets all safety standards. Once a vaccine is in use, its safety continues to be monitored.
Does the vaccine work?
The first dose of the vaccine should give you the highest level of protection about four weeks after you get it.
The vaccine may not prevent mpox completely, but if you do get it, your symptoms are likely to be milder.
Two doses provide longer-lasting protection, which is why it is important to have both doses of the vaccine.
After two doses of the vaccine, most people develop a good level of protection against mpox. The second dose can be given at least 28 days after your first dose.
Even after two doses, you should continue to be aware of the risks and symptoms of mpox as no vaccine is 100% effective. You should also continue to get tested for STIs (sexually transmitted infections) regularly.
Should I have the vaccine if I have had mpox already?
You can still be vaccinated if you have already had and recovered from an mpox infection. A previous infection with mpox does not mean you cannot get mpox again. If you meet the criteria, you should be offered the MVA vaccine.
Is there anyone who should not have the vaccine?
Very few people cannot have the mpox vaccination. You should not have the vaccine if you have had a serious (life-threatening) reaction to:
- a previous dose of the vaccine, or
- any ingredient in the vaccine.
The vaccine contains very small amounts of chicken protein and benzonase, as well as the antibiotics gentamicin and ciprofloxacin.
Speak to the person giving you the vaccine if you have had a serious allergic reaction to the vaccine or ingredients in the past.
If I am unwell, should I have the vaccine?
If you are unwell, it is better to wait until you have recovered to have a vaccine. A cold or other minor illness is not a reason to delay your vaccine.
If you have a high temperature and have been in close contact with someone who has confirmed mpox, you may need to be checked for early signs of mpox infection.
If in doubt, discuss this with the person giving you your vaccination.
What if I am taking other medicines?
Tell your doctor or nurse about any medicines you are currently taking or have recently taken. You should also tell them about any other vaccines you have recently had. In most cases, you should be fine to have the vaccine.
The vaccine is safe for people living with HIV and those taking PreP. You can also have the vaccine at the same time as other important vaccines, including those which protect against human papilloma virus (HPV), hepatitis A, hepatitis B and gonorrhoea.
What are the side effects of the MVA vaccine?
Like all medicines, vaccines can cause side effects. Most of these are mild and short-term, and not everyone gets them. Common side effects from the vaccine should only last a few days.
Common side effects include:
- pain, redness, swelling, hardness or itching where the injection was given
- a headache
- muscle aches or joint pain
- feeling sick
- tiredness
- chills and fever, and
- loss of appetite.
If you feel faint after the vaccination, you should wait for 15 minutes before you drive.
If you get any of the side effects listed above, you can rest and take the normal dose of paracetamol (follow the advice in the packaging) to help you feel better. Do not drive or use machines if you are feeling unwell.
If the side effects last for more than a few days, you should speak to a healthcare professional.
If you have atopic dermatitis (a form of eczema), you may get a stronger skin reaction from the vaccine. This can include redness, swelling and itching. You might also get other general symptoms, such as a headache, muscle pain, and feeling sick or tired. Your skin condition may also flare up or worsen.
Side effects may be more common in people who have previously had a dose of the old (live) smallpox vaccine.
To find out more about vaccine side effects:
- Imvanex MVA vaccine
Visit the MHRA Products website (external site). Type ‘Imvanex’ into the search box to find information and read the patient information leaflet.
- Jynneos MVA vaccine
Visit the FDA website (external site) to find information and read the patient information leaflet online.
If you have any questions or concerns about side effects, you can ask the person giving you the vaccine, visit the NHS 111 Wales website (external site) or contact NHS 111 Wales by calling 111.
Rarely, people can have a severe reaction soon after vaccination, which causes breathing difficulties and may cause them to collapse. This is called an anaphylactic reaction, and it can also happen with other medicines and food. These reactions are extremely rare, affecting less than one in a million people. Staff who give vaccinations are trained to manage these reactions.
People who have an anaphylactic reaction can be successfully treated and usually recover within a few hours.
Can I still get mpox if I am vaccinated?
Vaccination is one of the most effective ways to prevent severe illness from mpox. No vaccine is 100% effective, so it is still important to know the signs and symptoms of mpox, even if you are vaccinated.
For more information about mpox, visit:
I have atopic dermatitis – can I still have the vaccine?
You should tell the doctor or nurse if you have atopic dermatitis, as the risk of side effects from the MVA vaccine may be higher.
If you have atopic dermatitis, you may get stronger skin reactions to the vaccine, such as redness, swelling, and itching. You might also have other side effects, like headache, muscle pain, or fatigue. Your skin condition may also flare up or worsen.
I am HIV-positive – can I still have the vaccine?
Yes, you can have the vaccine if you are HIV-positive. However, if you have a very weakened immune system, the vaccine may not protect you as well. Let your doctor or nurse know that you are HIV-positive.
It’s recommended to avoid high risk sexual activity until after your second dose.
What if I am pregnant?
If you are pregnant, think you may be pregnant or are planning to have a baby, talk to your doctor or nurse before having the vaccination. The MVA vaccine does not cause smallpox or mpox, so it cannot spread to an unborn child.
Mpox may be more severe during pregnancy, and there is also a risk of passing mpox to your baby. Your doctor or nurse will help you understand the benefits of the vaccine and any possible risks.
Can I have the vaccine if I am breastfeeding?
If you are breast feeding, you can have the vaccine. It is unlikely that the vaccine will pass into your breast milk.
If you do get mpox, there is a risk of passing the infection to your baby, and mpox may be more severe in small babies. Your doctor or nurse can help to explain the benefits of vaccination.
Can the MVA vaccine be given to children?
Mpox can be more serious in children, particularly those under the age of five, so the vaccine is recommended for children and babies if they need it. Vaccines using the MVA virus appear to work very well. They also have an acceptable safety record in small children, with side effects similar to other baby vaccines.
The MVA vaccine has also been given safely to a number of children in the UK who have had contact with a person with mpox.
The vaccine can be offered to children after an assessment by a healthcare professional.
I am travelling to an area affected by mpox – do I need the vaccine?
The risk of mpox is low for most travellers. An mpox vaccine is not currently recommended for most people travelling to a country affected by mpox. Groups who are eligible for vaccination will be updated as more information becomes available.
If you are travelling to a country or area affected by an ongoing mpox outbreak, you should take special care to protect yourself by avoiding touch or sexual contact with anyone who is unwell or has a rash. For more information, visit the NaTHNaC website about Mpox (external site) .
To see the list of countries affected by mpox, visit the Travel Health Pro website (external site). You can also check the GOV UK foreign travel advice web page (external site) to see if the country you are visiting is affected by mpox.
If you have recently visited a country affected by mpox, be aware of mpox symptoms. If you develop any spots, blisters or sores within 21 days of coming home, stay at home and call NHS 111 Wales or your GP for advice. Make sure you tell them your recent travel history.
Can I have the mpox vaccine at the same time as other vaccines?
Yes. You can have the mpox vaccine at the same time as other important vaccines, including those which provide protection against HPV, hepatitis A, hepatitis B and gonorrhoea.
Page last reviewed: 25th July 2025