Mpox vaccines – frequently asked questions (FAQs)

Icon of vaccine vial with clipboard
Icon of vaccine vial with clipboard

NCIRS fact sheets, FAQs and other resources

Key points

  • Mpox is a disease caused by the monkeypox virus, which is in the same family as the virus that causes smallpox.
     
  • Mpox (previously known as monkeypox) is usually self-limiting, meaning it will resolve without any treatment; but it can cause severe illness, particularly in people who are immunocompromised, children and pregnant women.
     
  • Mpox vaccination is recommended for at-risk groups – specifically, gay, bisexual or other men who have sex with men (GBMSM); people living with human immunodeficiency virus (HIV); sex workers; and other individuals whose sexual networks might include GBMSM. It is also recommended for people at risk of occupational exposure to mpox (e.g. laboratory and healthcare workers). 
     
  • Close contacts (e.g. household members) of individuals who have been diagnosed with mpox should get vaccinated as soon as possible after exposure.
     
  • The main mpox vaccine in use in Australia, JYNNEOS, is effective and safe. People who are recommended to receive mpox vaccine should complete a 2-dose schedule of JYNNEOS vaccine (28 days apart) to maximise protection.
     
  • In Australia, the states and territories provide free JYNNEOS vaccine for at-risk groups.
     
  • There is an ongoing mpox outbreak in Australia and around the world. The Australian Technical Advisory Group on Immunisation (ATAGI) is continuing to monitor the evolving epidemiology of mpox disease and issue new recommendations as required.
     
  • ATAGI does not currently recommend booster doses of mpox vaccine for people who have already been fully vaccinated (2 doses) or who have previously been infected with mpox, including those who are severely immunocompromised. 
     
  • ATAGI now recommends pre-travel vaccination for anyone (regardless of sexual orientation or gender identify) who may undertake sexual risk activities during travel to countries with transmission of clade I mpox. 

FAQs

What is mpox?

Mpox is a disease caused by the monkeypox virus, which is in the same family of viruses that causes smallpox. 

In most people, mpox begins with general flu-like symptoms, followed by a blistering rash that can be painful. In some people, the rash is limited to one area of the body only. 

Some people can develop more severe mpox disease that needs to be managed in hospital. People with conditions that affect their immune system may be at greater risk of severe mpox. 

What are the signs and symptoms of mpox?

The signs and symptoms of mpox include: 

  • a distinctive rash that first appears as a flat sore, then changes into blisters before scabbing over; this rash may occur on any part of the body
  • swollen lymph nodes
  • fever
  • headache
  • muscle aches
  • joint and back pain
  • chills and fatigue. 

Symptoms typically begin to appear 5–21 days after exposure to the virus. 

How is mpox transmitted?

Mpox is spread from person to person through contact with the mpox rash, and especially through contact with fluid from mpox blisters. 

This contact can include sharing items like towels and linen, because virus that has been shed from the skin of an infected person can remain on these objects for some time.

Mpox can also spread through prolonged contact with the respiratory secretions (such as saliva) of a person with mpox. This may occur through intimate physical contact, such as kissing or oral sex.

Pregnant women can spread the virus to their unborn babies through the placenta. 

There are no known cases of mpox being spread through breastfeeding.

Which mpox vaccines are available in Australia?

The main mpox vaccine in use in Australia is called JYNNEOS (or MVA-BN). Overseas, the identical product may be known by its other brand names, Imvanex and Imvamune.

Another mpox vaccine, ACAM2000, is also available in Australia but is used infrequently, because it is more complicated to administer and has a less favourable safety profile than JYNNEOS.

Why are smallpox vaccines used against mpox?

JYNNEOS vaccine is indicated for use against both smallpox and mpox. Vaccines used against smallpox contain another virus – the vaccinia virus – that is closely related to both the smallpox and the mpox viruses. 

Evidence suggests vaccines that contain vaccinia virus can protect people against mpox in the same way they protect against smallpox. It has also been observed that people who were vaccinated against smallpox in their childhood have some protection against mpox many years later.

Who is recommended to receive mpox vaccine?

Mpox vaccination is recommended for the following groups who are at risk of exposure to mpox:

  • gay, bisexual or other men who have sex with men (GBMSM) 
  • transgender and gender-diverse people
  • sex workers, particularly those whose clients are at risk of mpox exposure
  • people living with HIV, if they are at risk of mpox exposure 
  • other individuals whose sexual networks might include GBMSM
  • laboratory personnel who work with orthopoxviruses (e.g. smallpox or monkeypox viruses)
  • healthcare workers who are at risk of exposure to patients with mpox.

People who have been in close contact with someone with mpox are also recommended to receive mpox vaccine as soon as possible – ideally, within four days of exposure.

Where can mpox vaccine be accessed?

In Australia, the states and territories coordinate the administration of mpox vaccines in their respective jurisdictions. 

Individuals can contact their relevant state and territory immunisation health service for the latest information on eligibility to receive mpox vaccine and how to access the vaccine.

How is mpox vaccine administered?

The preferred, standard route of administration for mpox vaccine is via subcutaneous injection. 

Due to limited vaccine supply at the start of the vaccination campaign in 2022, mpox vaccine was previously given mainly via intradermal injection, which allows for the administration of lower doses of vaccine (only one-fifth of a subcutaneous dose). 

While intradermal injection is as effective as subcutaneous injection in protecting against mpox, it requires the vaccinator to undergo specialised training. It also may cause more local reactions and is unsuitable for people with certain conditions (e.g. skin conditions, weakened immunities). 

Given the current sufficient supply of mpox vaccine, subcutaneous injection is now recommended. 

Are booster doses of mpox vaccine recommended?

People who have been fully vaccinated with 2 doses of mpox vaccine are not currently recommended to receive booster doses. 

For laboratory workers with ongoing occupational exposure to orthopoxviruses, a booster dose can be considered every 10 years.

Is mpox vaccine safe, and what are the common side effects of mpox vaccine?

JYNNEOS vaccine has been proven to be a safe vaccine, and more than a million doses have been given worldwide since the 2022 mpox outbreak. 

To date, most reactions reported after receipt of mpox vaccine have been mild and expected, such as pain and redness at the injection site that resolves within days. 

Serious vaccine-related adverse events were very uncommon in clinical trials of mpox vaccine and no major safety concerns have been reported.

For more information on reactions reported after receipt of the JYNNEOS vaccine in Australia, visit this AusVaxSafety page.

Can a person receive other vaccines at the same time as mpox vaccine?

JYNNEOS vaccine can be co-administered with other vaccines (i.e. given at the same visit), including COVID-19 and influenza vaccines. 

Currently, there are no data on the co-administration of mpox vaccines, but it is generally safe to co-administer inactivated (non-replicating) vaccines with other vaccines.

Can people who are immunocompromised receive mpox vaccine?

Yes, JYNNEOS vaccine can be given to people who are immunocompromised – including people living with HIV, who may have more severe disease outcomes if infected. 

For immunocompromised individuals who are at risk of mpox, 2 doses of mpox vaccine (28 days apart) are recommended. 

As with other vaccines, the effectiveness of mpox vaccine is expected to be lower in people who are immunocompromised than in immunocompetent individuals. 

Safety data relating to the use of mpox vaccine in people who are immunocompromised have not shown any significant safety concerns.

Can a person receive mpox vaccine while undergoing HIV treatment?

Yes, mpox vaccine can be administered to individuals receiving HIV treatment. 

Currently, there is no evidence that mpox vaccine interacts with medications given as part of HIV treatment (antiretroviral therapy) or HIV prophylaxis (pre- and post- exposure). 

It is important that people living with HIV get vaccinated against mpox while continuing any recommended HIV management.

If someone has previously received a smallpox vaccine, should they receive mpox vaccine?

People who are recommended to receive mpox vaccine and who received a smallpox vaccine more than 10 years ago only require a single dose of mpox vaccine. 

Clinical studies have shown the frequency of common side effects after mpox vaccination among people who have previously received a childhood smallpox vaccine and those who have not are largely comparable.

Can mpox vaccine be given to a person who has had close contact with someone with mpox?

Yes. People who have had close contact with a person known to have been infected with mpox are recommended to receive the mpox vaccine. This is known as post-exposure preventive vaccination. 

Depending on the timing and nature of the exposure and a range of other factors, 1 or 2 doses of mpox vaccine are recommended to prevent infection or reduce the severity of illness. 

The effectiveness of vaccination is likely to be highest if the vaccine is given as soon as possible following exposure – ideally, within four days.

It is important that people who may have been exposed to a person with mpox seek advice on vaccination from their relevant state and territory immunisation health service.

Is mpox vaccine recommended for people who have had a previous mpox infection?

If an unvaccinated or partially vaccinated person becomes infected with mpox, they do not need to receive the mpox vaccine in the short to medium term. At this time, naturally acquired mpox is believed to confer immune protection – although the duration of this immunity is currently unknown.

What are the recommendations for a partially vaccinated person who is at risk of mpox or in close contact with someone with mpox?

People who are at risk of exposure to mpox should complete a 2-dose primary course of mpox vaccine. Those who have only received 1 dose should receive a second dose as soon as possible. 

If a partially vaccinated person comes into close contact with someone with mpox, the following is recommended: 

  • If the contact occurred less than 28 days after the first dose (i.e. the first dose may not be valid): Receive 1 dose as post-exposure preventive vaccination immediately (ideally, within four days of exposure) and another dose 28 days later to complete the course. It typically takes around 28 days for a vaccine dose to become fully effective, so this gap between doses allows the immune system to build up a protective response.
  • If the contact occurred more than 28 days after the first dose: Receive 1 dose as post-exposure preventive vaccination immediately (ideally, within four days of exposure).
Can pregnant or breastfeeding women receive mpox vaccine? 

Yes, mpox vaccine can be offered to pregnant or breastfeeding women who are at risk of mpox exposure. 

While relevant data are currently limited, there are no expected safety concerns in relation to administering mpox vaccine to pregnant women. 

The risk of mpox exposure, infection and serious outcomes in a pregnant woman or her foetus is best determined through an individual risk assessment. This can be undertaken in conjunction with the relevant state or territory health authority.

Can mpox vaccine be given to individuals aged under 18 years who are at risk of infection?

Yes. While JYNNEOS vaccine is currently only registered for use in people aged 18 years and over, it is recommended – and can be prescribed by a medical practitioner – for anyone considered to be at risk of mpox exposure. 

Mpox vaccine can be used as post-exposure preventive vaccination in children and adolescents if they are or have been in contact with someone with mpox, after an individualised risk assessment.

There are no expected safety concerns in relation to administering mpox vaccine as a post-exposure preventative vaccination to children and adolescents who have come into close contact with someone with mpox. 

Immunisation providers who are considering administering mpox vaccine to a person aged under 18 years should consider following the United States Centers for Disease Control and Prevention Clinical considerations for mpox in children and adolescents.

How effective is mpox vaccine?

Real-world studies have shown 2 doses of JYNNEOS vaccine are effective for preventing mpox and have a vaccine effectiveness around 66% to 86%. 

Vaccine effectiveness in fully vaccinated immunocompromised people – including people living with HIV and people who are immunodeficient due to medications or conditions – has been found to be lower than in immunocompetent people (70.2% vs 87.8%, respectively).

Data relating to vaccine effectiveness for post-exposure preventive vaccination are limited; however, two studies have shown it to range from 73% to 89%.

Does mpox vaccine need to be reported to the Australian Immunisation Register (AIR)?

All vaccines, including mpox vaccine dose(s), should be recorded on the AIR – the national register that records vaccines given to all people in Australia. It is mandatory to report some vaccines.  

If required, evidence of mpox vaccination can be hidden on official statements, including on an individual’s Immunisation History Statement. 

A complete vaccination record can assist in determining a person’s future vaccine recommendations. For more information, contact the AIR on 1800 653 809.

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