Imvamune Vaccine FAQs

What is Imvamune?

• Imvamune vaccine is approved in Canada for protection against smallpox, mpox (previously known as monkeypox), and other orthopoxvirus-related illnesses.
• It is a live vaccine, but it contains weakened virus and cannot make you sick.
• The vaccine is free and available to all eligible people. No ID or OHIP required.
• Two doses of Imvamune at least 28 days apart are recommended unless supply is low.
• Imvamune cannot be used to treat mpox.

Who should get the mpox vaccine?

• The vaccine can be used for protection for people who are at high risk of exposure to the mpox virus before getting exposed (Pre-Exposure Prophylaxis – PrEP)
• The following groups are now eligible for Imvamune:
  1. Two-Spirit, non-binary, transgender, cisgender, intersex, or gender-queer individuals who self-identify as belonging to the gay, bisexual, pansexual and other men who have sex with men (gbMSM) community AND who meet one or more of the following:
     • Have more than one partner
     • Are in a relationship where at least one of the partners has other sexual partners
     • Have had a confirmed sexually transmitted infection within the last year
     • Have attended venues for sexual contact (e.g., bath houses, sex clubs)
     • Have had anonymous sex (e.g., using hookup apps) recently
  2. Sexual partners of individuals who meet the criteria above
  3. Sex workers (regardless of gender, sex assigned at birth, or sexual orientation) or who are a sexual contact of an individual who engages in sex work
  4. Staff or volunteers in sex-on-premises venues where workers may have contact with fomites potentially contaminated with mpox
  5. Individuals who engage in sex tourism (regardless of gender, sex assigned at birth, or sexual orientation)
  6. Individuals who anticipate experiencing any of the above scenarios
• Household contacts of those identified for pre-exposure vaccination eligibility above AND who are moderately to severely immunocompromised or who are pregnant may be at higher risk for severe illness from mpox infection and may be considered for pre-exposure vaccine.
• The vaccine may also be used after a possible exposure / close contact with someone with mpox (Post-Exposure Prophylaxis – PEP).
  • The vaccine should ideally be given within four days of exposure but can be given up to 14 days after the last exposure.
• At this time, people who have or have had mpox are not eligible for the vaccine.

Is the vaccine safe and effective?

• Yes, Imvamune is safe to receive and provides effective protection against the mpox virus.
• The National Advisory Committee on Immunization (NACI) recommends that Imvamune may be offered to the following special groups if there is an exposure risk, after a risk / benefit discussion with your health care provider—if you are pregnant, breastfeeding, immunocompromised, have atopic dermatitis, or are less than 18 years of age. 

Who should not receive the vaccine?

• If you are experiencing any symptoms of mpox, it is important to isolate right away and contact a health care provider. The vaccine is not used to treat mpox.
• Wait to get vaccinated if you have any COVID-19 symptoms, such as a high fever, and/or you are required to self-isolate.
• Imvamune should not be given to individuals who have allergies to any of the ingredients in the vaccine including trometamol or benzonase. It has a bromobutyl rubber stopper.
• There are trace amounts of gentamicin, ciprofloxacin and egg products, but hypersensitive individuals can safely receive Imvamune and just need to stay 30 minutes for observation.
• If you have a history of myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the outer lining of the heart) linked to a previous dose of a 1st or 2nd generation smallpox vaccine, speak to your health care provider.

What are the common side effects of Imvamune?

• Some people may feel sore and swollen for a few days where the needle was given, have a slight fever or feel tired for a day or two.
• Other common side effects may include fatigue, headache, muscle aches/pain, and nausea.
• Tylenol or ibuprofen may be taken afterwards, as directed, to reduce discomfort or fever.
• Children under 19 years of age must not be given ASA, Aspirin® or salicylates.

What else do I need to know?

• After getting the vaccine, it takes two weeks to build protection. During these two weeks, consider reducing your number of close contacts, including sex partners.
• NACI states that Imvamune can be given concurrently (for example, on the same day) or at any time before or after other live or non-live vaccines.
• If you have already had an older generation live smallpox vaccine you can be re-vaccinated.

When should I seek medical attention after immunization?

• If you or your child experiences any unusual side effects, seek medical attention & notify us.
• Go to Emergency at a hospital right away or call 911 if you or your child has any of the following after immunization:
  • swelling of the face and neck
  • problems breathing or shortness of breath
  • hives and itchy, reddened skin
  • chest pain or a pounding heartbeat

References

• Imvamune product monograph  
• MPX Vaccine Information Sheet Ministry of Health
• NACI Interim guidance for use of Imvamune in context of MPX 
• Toronto Public Health Mpox
• Canadian Immunization Guide MPOX: Vaccination Clinic Resources  
• Mpox Resources for HCPs

Your Record of Protection

After you receive any immunization, make sure your health care provider updates your personal immunization record. Keep it in a safe place. Please inform Hastings Prince Edward Public Health of any immunizations not received from us.

Imvamune vaccine for Mpox printable fact sheet (pdf)