What is MPox?
Mpox is an infectious disease that is caused by infection with monkeypox virus (MPXV).
Mpox was first discovered in 1958 when outbreaks of a pox-like disease occurred in monkeys kept for research. The first human case was recorded in 1970 in the Democratic Republic of the Congo (DRC), and since then the infection has been reported in a number of African countries. Prior to 2022 most cases were reported from the DRC and Nigeria.
Mpox 2024
In 2024, Clade I mpox cases were reported from countries in Africa beyond these 5 Central African Region countries. This is likely to be because of multiple factors including waning population immunity from the discontinued smallpox vaccine and changing environmental and social factors, but the full aetiology remains unclear.
Clade I MPXV has previously been intermittently transmitted from animals to humans, with small mammals and primates acting as hosts. Clade I MPXV can also spread via human-to-human transmission and had previously been associated with close contact. However, in March 2023, infections linked to sexual contact and international travel were reported in the DRC for the first time.
As of August 2024, no cases of Clade I mpox have ever been detected in the UK.
How is it transmitted?
Mpox does not spread easily between people unless there is very close contact.
The virus is transmitted through skin-to-skin contact, breathing in virus through the respiratory tract, or contact with mucous membranes (eyes, nose, mouth, genitals).
Person-to-person spread may occur through:
- direct contact with skin lesions or scabs (including during sexual contact, kissing, cuddling or other skin-to-skin contact)
- coughing or sneezing of someone who has mpox when they’re close to you
- contact with clothing or linens (such as bedding or towels) used by someone with mpox
Spread of mpox may also occur when a person comes into close contact with an infected animal (rodents are believed to be the primary animal reservoir for transmission to humans), human, or materials contaminated with the virus. Mpox has not been detected in animals in the UK.
What are the symptoms?
The incubation period is the duration/time between contact with the person with mpox and the time that the first symptoms appear. The incubation period for mpox is between 5 and 21 days.
Mpox infection is usually a self-limiting illness and most people recover within several weeks. However, severe illness can occur in some individuals.
The illness begins with:
- fever
- headache
- muscle aches
- backache
- swollen lymph nodes
- chills
- exhaustion
- joint pain
However, not all people who have mpox experience all of these symptoms. Within 1 to 5 days after the appearance of fever, a rash develops, often beginning on the face then spreading to other parts of the body including the soles of the feet and palms of the hands. Lesions can also affect the mouth, genitals and anus. The rash changes and goes through different stages before finally forming scabs which eventually fall off.
Some individuals may not have a widespread rash, and in some cases only genital lesions are present. These may be blisters/vesicles, scabs or ulcers.
An individual is contagious until all the scabs have fallen off and there is intact skin underneath. The scabs may also contain infectious virus material.
Images of individual mpox lesions
How is it treated?
Treatment for mpox is mainly supportive. Non-HCID mpox is usually mild and most of those infected will recover within a few weeks without treatment.
Antiviral drugs such can be used to treat mpox patients with severe disease or those who are at high risk of severe disease.
Infection prevention and control
Prevention of transmission by respiratory and contact routes is required. Appropriate precautions are essential for suspected and confirmed cases. Scabs are also infectious and care must be taken to avoid infection through handling bedding and clothing. Information on infection prevention and control measures are available in the National infection prevention and control manual for England.
Who is offered the MPox vaccine?
Mpox is caused by a virus similar to the one that causes smallpox. So vaccines designed for smallpox are expected to prevent or reduce the severity of mpox.
The vaccine used in Scotland contains a virus that’s been modified so that it cannot grow in the human body. This Modified Vaccinia Ankara (MVA) vaccine is a much safer form of the smallpox vaccine. MVA vaccines do not contain smallpox virus and cannot spread or cause smallpox.
The MVA (Imvanex) vaccine has been authorised for immunisation against mpox as well as smallpox by the Medicines and Healthcare products Regulatory Agency (MHRA).
As there is no UK branded vaccine available, you may be offered the US labeled equivalent of the MVA (Imvanex) vaccine, which is called Jynneos. This is the same vaccine as Imvanex and is also approved for mpox.
Read the IMVANEX patient information leaflet
Read the JYNNEOS patient information leaflet
The vaccine helps the immune system (the body’s natural defence system) produce its own protection in the form of antibodies against the smallpox virus.
The vaccine is recommended for people whose sexual networks mean they are more likely to come into contact with mpox. These include:
- gay, bisexual, men who have sex with men (GBMSM), those who have multiple partners, take part in group sex, attend sex on premises venues, or have had a bacterial STI such as chlamydia, gonorrhoea or syphilis in the past year
- some trans and non-binary people who are in similar sexual networks to GBMSM
- some healthcare workers in high-risk settings where they may care for a patient with mpox
How many doses will be offered?
A full course of 2 doses of vaccine given at least 28 days apart is recommended for those at risk of mpox exposure.
Where can I get the vaccine?
If you’re eligible, some specialist sexual health clinics are offering the MVA vaccine.
Find my nearest sexual health service
Healthcare workers at higher risk will be offered the vaccine from their employer.
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