Norway has been allocated a limited number of vaccine doses for use against mpox. The vaccine will therefore only be prioritised for people with a particularly high risk of infection, and for close contacts of people 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) 

Since the number of doses is limited, vaccination before potential exposure (primary preventive vaccination, PPV) can only be offered to people at particularly high risk of infection (see table below). People in priority groups 1 and 2 will be offered the vaccine. It is currently not being offered to priority group 3.

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 meet the criteria for vaccination in priority group 1, you should contact the doctor in the specialist health service where you are usually treated. If you meet the criteria for priority group 2, you should contact your municipality to find out how registration for vaccination is being organised.

When you show up for vaccination, you must bring a valid ID. Vaccination will be registered in medical records and registered in the Norwegian immunisation registry, SYSVAK. 

The person giving the vaccine will have to vaccinate several people on the same day because one vial of vaccine is enough for 3-5 people and the vaccine has a short shelf life. It is therefore important that you attend the appointment you are given.

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 is placed in the outermost layer of skin (intradermally) on the upper arm so that a small blister forms, which disappears after 5-10 minutes. A reduced (fractionated) volume of the vaccine (0.1 ml) will be used.

• People who have not previously received the smallpox vaccine:
  • Two doses intradermally, 28 days apart.
  • The vaccine will also be effective if other doses are given after more than 28 days.
  • If mpox is detected after the first dose, there is no need to take a second dose.
• People who have previously been vaccinated with smallpox vaccine (born before 1976 and who either have documentation of vaccination or scars after vaccination):
  • One dose intradermally
  • People with immunodeficiency should receive two doses.

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 have previously been vaccinated against smallpox do not need a second dose, unless they are immunocompromised.

• 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 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.

Access to vaccines and the dose prioritisation varies between countries, so there is no routine where people who have received their first dose abroad will be offered further vaccination in Norway. Further vaccination in Norway is offered if the Norwegian priority criteria are met.

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? 

If you were born before 1976 and have a visible scar after vaccination, a single booster dose is sufficient because the immune system will remember having been in contact with the vaccine virus previously. If you are immunocompromised, you should receive two doses even though you have been vaccinated previously. 

It is uncertain whether previous smallpox vaccination gives protection against mpox.

Healthcare personnel 

Due to the low risk of transmission and limited access to vaccine doses, healthcare personnel are currently not offered the vaccine. Healthcare personnel who treat infected people, or those who have a high probability of contact with infected people, are recommended to follow advice about infection control measures in the health service. Health personnel who are also close contacts can be offered the vaccine after 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 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? 

People in the prioritised groups must 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

Globally, there is very limited access to vaccines against mpox. The vaccine distribution to European countries has been made by the EU's health preparedness and response authority, HERA, based on each country’s population. Through this, Norway has been offered a limited number of vaccine doses. It takes time to produce this type of vaccine, and it is unclear when more vaccine doses will be available. 

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.  

The vaccine was initially developed and approved for injection under the skin (subcutaneous), but recently it has been allowed to also inject the vaccine into the outermost layer of the skin (intradermally). When vaccines are injected in the outermost layer of the skin, the immune response is heightened, so a lower volume can be used, as is seen with some other vaccines (for example the BCG vaccine). Based on clinical data showing that vaccination with 0.1 ml in the outermost layer of the skin produces as good an antibody response as 0.5 ml placed in the subcutaneous tissue, regulatory authorities in the USA (FDA) and Europe (EMA) have allowed the vaccine to be given either intradermally or subcutaneously. If the vaccine is injected intradermally, only one fifth of the original volume is used. This means that there will be more doses available in a situation where there is limited access to vaccines globally.