About the mpox vaccine
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|Updated
In this article you can read about who is recommended to take the mpox vaccine, how and where you will be offered the vaccine and about the vaccine’s effect and side effects.
Norway has a vaccine that can be used against mpox. The vaccine is offered to individuals at risk of infection and to close contacts of people who have been diagnosed with mpox. Vaccination alone is not enough to limit transmission of mpox, so other infection control measures will still be necessary.
Who is recommended to be vaccinated?
Vaccine before exposure (primary preventive vaccination, PPV)
Preventive vaccination (primary preventive vaccination, PPV) is offered to individuals who have an increased risk of contracting mpox.
Groups eligible for primary preventive vaccination (PPV) against mpox (monkeypox):
- Men or transgender individuals who have sex with men AND report risk behaviors (e.g., new or multiple sexual partners)
- Sex workers
- Healthcare personnel and others who are expected to have real close contact with mpox patients as part of their work
- Laboratory personnel who work with live monkeypox virus (neutralization tests, cell cultures, etc.)
Vaccine after possible exposure (post-exposure vaccination, PEPV)
The vaccine will also be offered to people after possible infection (post-exposure vaccination, PEPV) if they have been in close contact with people who have been diagnosed with mpox. PEPV is offered after a specific assessment by a doctor based on the risk of infection depending on the type of contact, the time that has elapsed since contact, and the risk of a severe disease course.
People who have a high probability of infection (high-risk contacts, sexual contacts and household members) can be vaccinated within the first four days after possible infection to reduce the risk of disease development.
People who are high-risk contacts and who have a high risk of a severe disease course (young children, pregnant women, and people with immunodeficiency) can be offered a vaccine up to and including day 14 after exposure to reduce the risk of a severe disease course.
The use of the vaccines is constantly assessed by the Norwegian Institute of Public Health, and it may therefore be relevant to adjust who is recommended for vaccination and their prioritisation.
Where and how will I be offered vaccination?
Offer of primary preventive vaccination (PPV)
If you belong to the vaccination target group, you should check how registration and vaccination services are organized in your municipality.
Some healthcare institutions may offer the vaccine to people with HIV or users of HIV PrEP. If you belong to this group, you can inquire at your usual follow-up location.
When you arrive for vaccination, you must bring a valid ID. The vaccination will be documented in your medical record and registered in the national vaccination registry, SYSVAK.
Offer of post-exposure vaccination (PEPV)
When a person is diagnosed with mpox, the doctor will start contact tracing and map close contacts. During contact tracing, the doctor will not disclose the identity of the person who has been diagnosed. Depending on the type of contact, time since contact and individual risk of a severe disease course, people who have been exposed to infection may be offered vaccination.
The vaccination will be documented in medical records and registered in the Norwegian immunisation registry, SYSVAK, and will be available when you log in to Helsenorge.no.
How is the vaccine given?
Primary preventive vaccination (PPV)
The vaccine can be administered either subcutaneously (under the skin) or intradermally (into the outermost layer of the skin) on the upper arm. If the vaccine is administered subcutaneously, a full dose (one vial of 0.5 ml) is used. If it is administered intradermally, a reduced (fractionated) volume of the vaccine (0.1 ml) is used. This method can be employed if multiple people need to be vaccinated simultaneously. A small blister will form on the skin, which will disappear after 5-10 minutes.
- Two doses should be given 28 days apart. The vaccine will still be effective even if the second dose is administered later than 28 days.
- Individuals who are diagnosed with mpox after the first dose should not receive the second dose.
Post-exposure vaccination (PEPV)
- For post-exposure vaccination, the full vaccine dose (0.5 ml) is used
- The dose is placed under the skin (subcutaneous).
- People who have a persistent risk of infection are still symptom-free after 28 days will be offered a second dose
- People who are diagnosed with mpox after the first dose should not have a second dose.
Effect
Effect of primary preventive vaccination (PPV)
The duration and degree of protection after one dose is currently unknown. A milder course of the disease is expected if someone is infected after the first vaccination dose, but they can presumably still infect others. The protection will be better and last longer after the second dose. It has been shown that the antibody level reaches its peak approximately two weeks after the second dose.
When one to two weeks have passed after the second dose, we assume that the vaccine protects well against a severe disease course. However, it is still not certain that everyone will be fully protected against contracting mpox and against infecting others. Therefore, vaccinated people should also follow other infection control advice.
The effect of the vaccine probably decreases over time. The need and possible timing for a booster dose has not been clarified.
Effect of post-exposure vaccination (PEPV)
It is assumed that the vaccine can prevent disease if it is given 0-4 days after close contact with an infected person. If it is given 5-14 days after close contact, it can probably prevent the development of a severe disease course. This is based on animal studies. If you develop symptoms of mpox despite post-exposure vaccination, you can probably transmit the infection to others, even if the symptoms are mild.
Side effects
The most common side effects are:
- Pain, redness, tenderness, swelling, itching at and around the injection site (very common)
- General reactions such as muscle pain, headache, nausea and lethargy (very common)
- Discolouration of the skin, bruising, feeling warmth and coolness at the injection site (common)
- Joint pain and fever (common)
Most side effects resolve on their own without treatment within a week of vaccination, but scarring and permanent pigment changes may occur.
It is assumed that the vaccine will cause more frequent, stronger and longer-lasting side effects when given intradermally, particularly after the second dose.
People with atopic eczema have an increased risk of side effects and can experience worsening of eczema.
For a full list of known side effects, see the full product information (SPC).
What if I have side effects after vaccination?
If you experience unexpected, severe or long-lasting health problems, you should contact a doctor or other healthcare professional for assessment and advice. This applies regardless of whether you think it is due to the vaccine or not.
As there is little experience with the use of this vaccine, it is subject to special monitoring to discover new safety information as quickly as possible. Healthcare professionals are encouraged to report any suspected side effects to melde.no. Alternatively, if you who have been vaccinated you can report a suspected side effect yourself via helsenorge.no. All notifications, regardless of whether they are reported by you or healthcare personnel, are stored in the same database. You do not need to report a side effect if a healthcare professional has already reported it on your behalf.
If symptoms consistent with mpox appear after vaccination, you should avoid close contact and consult a doctor. If mpox is detected among people who have received one or two doses of the vaccine, this should be reported as vaccine failure to melde.no. You do not need to report a side effect if a healthcare professional has already reported it on your behalf.
What if I am vaccinated abroad?
People who have received mpox vaccine abroad are recommended to have the vaccination post-registered in SYSVAK. Doctors, municipal health services and private health services may be able to help with this. The Norwegian Institute of Public Health cannot post-register vaccines.
If you have received PEPV abroad, you can be offered a second dose in Norway if you are exposed to a persistent risk of infection and can document vaccination abroad. Contact a doctor in Norway for assessment of further vaccination.
Already vaccinated against smallpox?
It is uncertain whether previous smallpox vaccination gives protection against mpox.
The mpox vaccine is given regardless of any previous smallpox vaccination.
Healthcare personnel
Vaccination can be considered for healthcare personnel and others who are particularly at risk of infection through their work, such as staff at testing stations or those working directly with patients hospitalized with mpox.
Healthcare personnel who examine and treat infected individuals or are highly likely to come into close contact with infected persons are advised to follow recommendations on infection control measures in healthcare settings. Healthcare personnel who are close contacts may be offered the vaccine based on an individual assessment.
Employees in the health service who are at risk of complications from infection with the mpox virus, such as pregnant women and employees with immunodeficiencies, are advised not to work with people with suspected, probable or confirmed mpox.
Children
Children less than 12 years of age should only be vaccinated if they have been exposed to infection and after individual assessment by their doctor in consultation with the NIPH. In the current outbreak of mpox, a few children in Europe have so far received the vaccine after exposure to infection (post-exposure vaccination), and no unexpected events have been reported.
Pregnancy and breastfeeding
There are limited data about the use of this type of vaccine among pregnant and breastfeeding women. Pregnant women are at increased risk of a severe mpox disease course, and the disease can be transmitted to the foetus. The risk is probably higher towards the last trimester. Pregnant women who have been exposed to infection can be vaccinated after a careful assessment of benefit and risk. Breastfeeding women can be vaccinated.
Who should not be vaccinated?
Individuals should not be vaccinated if they have:
- Known allergy to ingredients in the vaccine. The vaccine contains trace amounts of chicken protein, benzonase, gentamicin and ciprofloxacin and its use is contraindicated in people with a known allergy to these.
- Acute infectious disease with a fever above 38 °C
There is no need for vaccination after an earlier mpox infection
People with symptoms of mpox should not be vaccinated.
If a strong local reaction to the first dose persists until the second dose is to be administered, it is recommended that the second dose is postponed until the local reaction has passed. Inform the vaccination clinic a few days in advance so they can plan accordingly.
People with a tendency to excessive scarring (keloid) should not be vaccinated in the skin (intradermally) but should be offered vaccination under the skin (subcutaneous) with a full dose (0.5 mL).
Vaccine used in Norway
The Imvanex vaccine which is available in Norway was initially developed as a contingency vaccine against smallpox. The vaccine is a third-generation smallpox vaccine and contains live virus that has been weakened to such an extent that it can no longer reproduce in the body's cells.
Since mpox is caused by a virus related to the smallpox virus, smallpox vaccines are expected to be effective against mpox. However, there is little experience with the use of this vaccine. Two doses likely provide good protection against severe illness and reduce the risk of transmission. However, there have been several reports indicating that vaccinated individuals can still become infected and spread the virus, although they appear to experience milder symptoms. Therefore, it remains important to get tested if symptoms arise and to follow other infection control measures, even if you are vaccinated.
The vaccine was originally developed and approved for subcutaneous injection (under the skin), but during the 2022 outbreak, it was also authorized for injection into the outermost layer of the skin (intradermal). This allowed for the vaccination of more people in a situation where there was limited global access to vaccines. When vaccines are administered intradermally, the immune response is stronger, allowing for a lower volume to be used, as is known from some other vaccines (e.g., the BCG vaccine). Norway has now received more doses of the vaccine, making it possible to offer the vaccine subcutaneously rather than only intradermally.