Summary of NACI statement of May 24, 2024: Interim guidance on the use of Imvamune^® in the context of a routine immunization program

On this page

• Overview
• What you need to know

Overview

• On May 24, 2024, the Public Health Agency of Canada (PHAC) released interim guidance from the National Advisory Committee on Immunization (NACI) on the use of Imvamune^® in the context of a routine immunization program.
• This guidance is based on current evidence and NACI expert opinion and builds on NACI's updated interim guidance on Imvamune^® in the context of ongoing monkeypox outbreaks published on September 23, 2022.
• In the context of a focused routine immunization program, NACI recommends that individuals at high risk of mpox should receive two doses of Imvamune^®, administered by subcutaneous injection at least 28 days apart. After considering current clinical evidence and ongoing epidemiology, NACI recommends the following individuals receive Imvamune^® (Strong NACI Recommendation):
  • Men who have sex with men (MSM) who meet one or more of the following criteria:
    • 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 acquired in the last year
    • Have engaged in sexual contact in sex-on-premises venues
  • Sexual partners of individuals who meet the criteria above.
  • Sex workers regardless of gender, sex assigned at birth, or sexual orientation.
  • Staff or volunteers in sex-on-premises venues where workers may have contact with fomites potentially contaminated with mpox.
  • Those who engage in sex tourism regardless of gender, sex assigned at birth, or sexual orientation.
  • Individuals who anticipate experiencing any of the above scenarios.
• Completion of the two dose-series will provide optimal protection. Individuals who received one dose of Imvamune^® should receive the second dose, even if months have elapsed.
• Those who have previously received smallpox vaccination and are recommended to receive Imvamune^® based on risk factors for mpox should also receive a 2-dose series with a minimum interval of 28 days.

NACI defines MSM as any man or Two-Spirit identifying individual who has sex with another person who identifies as a man, including but not limited to individuals who self-identify as trans-gender, cis-gender, Two-Spirit, gender-queer, intersex, and non-binary.

NACI will continue to monitor the evolving evidence and will update guidance as needed.

For the full statement, including supporting evidence and rationale, please see NACI's interim guidance on the use of Imvamune^® in the context of a routine immunization program.

What you need to know

• Mpox is a viral disease that is typically mild and self-limiting, but can lead to severe disease in some populations, such as young children, pregnant women and pregnant people, and immunocompromised individuals.
• Although occurrences are less frequent compared to during the 2022 multi-country outbreak, mpox cases are still being reported in Canada, with the greatest burden of disease among gay, bisexual, or other men who have sex with men (gbMSM). There is potential for a future resurgence.
• Based on the success of the emergency mpox vaccine program in helping to mitigate the mpox outbreak in Canada since 2022, NACI now recommends routine immunization with Imvamune^® to individuals considered at high risk of mpox, including gbMSM who meet high risk criteria and sex workers who have not yet been vaccinated with two doses.
• At this time, Imvamune^® is not routinely recommended for healthcare workers, including those serving populations at high risk of mpox, with the exception of post-exposure vaccination. Mpox cases seen among this group were primarily acquired outside the context of a healthcare setting. If exposed, post-exposure vaccination is still encouraged.
• Individuals at high risk of mpox and who are planning to travel internationally should consult with their healthcare provider to discuss vaccination preferably 4 to 6 weeks prior to travel, particularly those travelling to countries with ongoing mpox transmission.
• NACI continues to recommend that Imvamune^® should be offered to people who are immunocompromised, pregnant or breastfeeding, if vaccination is recommended based on high-risk criteria. Off-label use in pediatric populations may be considered for those meeting the high-risk criteria, at their clinician's discretion.
• Imvamune^® vaccination can be given concurrently (i.e., same day) or at any time before or after other live or non-live vaccines including COVID-19 vaccines.
• So far, there is no evidence to suggest that additional doses of Imvamune^® (e.g. more than 2 doses) are needed for individuals in the context of a routine immunization program, including immunocompromised populations. Evidence will continue to be reviewed on this topic as it becomes available. NACI continues to recommend that personnel working with replicating Orthopoxviruses in laboratory settings be offered an additional dose after 2 years if they remain at risk of occupational exposure.
• This NACI guidance on the use of Imvamune^® in the context of a routine immunization program should be considered interim and will be re-evaluated once additional evidence emerges.

For the full statement, including supporting evidence and rationale, please see NACI's Interim guidance on the use of Imvamune^® in the context of a routine immunization program.

For more information on NACI's recommendations on the use of Imvamune^® vaccines, including mpox post-exposure advice, please refer to the Smallpox and mpox (monkeypox) vaccines chapter in the Canadian Immunization Guide (CIG), as well as additional statements on the NACI web page.