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Mpox (formerly known as monkeypox) Information for Physicians

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Effective June 16, 2022, mpox has been designated a Disease of Public Health Significance (DOPHS) as “Smallpox and other Orthopoxviruses including Mpox” under the Health Protection and Promotion Act (HPPA).

Persons required reporting DOPHS and/or communicable diseases under the HPPA are now required to report directly to the local Medical Officer of Health in accordance with the reporting requirements in the Act, as per routine disease processes.

Suspect, probable, and confirmed cases of mpox must be reported to Halton Region Public Health by calling 905-825-6000, ext. 7341 during regular business hours and 311 after hours.

Complete page 1 of the Ontario mpox Investigation Tool (external link) and fax to Halton Region Public Health at 905-825-8797.

  • Laboratory testing is helpful for reporting and case/contact management purposes for any individual with rash/symptoms similar to mpox, either testing for mpox and/or other infections on the differential diagnosis.
  • Testing for mpox can be done by primary care providers with the specimen having the same transport requirements (i.e. category B) as other microbiology specimens such as a swab collected for gonorrhoea, blood collected for syphilis, urine for routine culture and susceptibility.
  • The outer packaging (bag) must be labelled certified for UN3373 and must be marked on a contrasting background with “TU 0886 Temporary Certificate”.
  • All specimens from a patient being investigated for mpox, including specimens submitted for other tests, should indicate on the requisition that this patient is suspected of having mpox.
  • All specimens from a patient being investigated for mpox are considered dangerous goods and as such, appropriate training is required for the handling, offering for transport, or transport of the specimens. For more information on training, refer to guidance from Temporary Certificate TU 0886 (external link).
  • Detailed information on testing, specimen collection and specimen transport is available on PHO Lab website (external link).

Public Health agencies around the world have reported cases of mpox, a self-limiting orthopoxvirus, since May 2022. The main route of mpox virus transmission is direct close contact (skin-to-skin), particularly through sexual contact. The virus causes a flu-like illness that leads to a maculopapular rash.

Symptoms may begin in a prodromal phase that includes:

  • Fever/chills
  • headache
  • swollen lymph nodes
  • intense fatigue
  • sweating
  • muscle aches
  • joint stiffness

The incubation period is usually 6 to 13 days but can range from 5 to 21 days. Within 1-3 days after symptom onset, a rash appears at the site of inoculation, then may appear on other parts of the body including oral mucosa, genital area, conjunctiva, palms of the hands and soles of the feet.

Atypical presentations include initial signs of a genital or perianal rash prior to prodrome symptoms which may not spread to other parts of the body, and having lesions at different stages of development. The rash turns into vesicular lesions that will eventually fall off to be replaced by new skin. The time for scabs to fall off varies by individual but typically takes 2-4 weeks.

Epidemiology on the 2022-2023 outbreak shows that mpox has mainly affected gay, bisexual, and men who have sex with men (gbMSM) who have more than one, new, and/or anonymous sexual partners. In addition, many of these cases have reported atypical symptoms, including painful unusual rash/lesions in the mouth and/or genitals.

As the situation continues to evolve, guidance is being updated frequently. For up to date recommendations, please see IPAC Recommendations for Mpox in Health Care Settings (external PDF).

If a patient has symptoms of mpox, they should immediately self-isolate and call their health care provider. If contact with others is mandatory (e.g., seeking health care), patient should wear a high quality medical mask and cover up all lesions.

Consider the diagnosis of mpox in individuals with signs and symptoms that may be compatible with the disease such as a rash that includes painful genital/oral lesions, fever, lymphadenopathy, chills and/or sweats, headache, back pain/ache, sore throat and/or cough, coryza, malaise/listlessness, and prostration/distress.

At this time, Public Health will follow up with all reported cases. Cases must isolate at a minimum until test results are received and until they meet the criteria outlined in the Recommendations for the management of cases and contacts of mpx in Ontario (external PDF file). Contacts should monitor for symptoms for 21 days after their last exposure. If they develop a fever or rash, they should immediately self-isolate, contact Public Health, and see their primary health care provider.

Key Messages

  • Imvamune® vaccine is approved in Canada for protection against mpox (external PDF) for both pre-exposure vaccination and post-exposure vaccination.
  • Individuals with signs or symptoms of mpox infection should not receive the vaccine as the vaccine is not indicated in the treatment of mpox infection.
  • Recent Ontario data has shown that persons who have received at least one dose of Imvamune® are less likely to report severe symptoms and to require hospitalization than persons who have not been vaccinated.
  • Recent studies have shown vaccine effectiveness to be between 66-83% for patients with a 2 dose vaccine series.
  • The most common side effects of Imvamune® vaccine include reactions at the injection site like pain, erythema, induration and swelling. The most common systemic reactions observed after vaccination are fatigue, headache, myalgia, and nausea. Most of the reported adverse drug reactions observed in clinical trials were of mild to moderate intensity and resolved within the first seven days following vaccination.

Imvamune® vaccine for Pre-Exposure Vaccination

Based on Ontario Ministry of Health's guidelines (external PDF), persons who qualify for pre-exposure vaccination at this time are:

  1. Two-Spirit, non-binary, transgender, cisgender, intersex, or gender-queer individuals who self-identify or have sexual partners who self-identify as belonging to gay, bisexual, pansexual, and other men who have sex with men (gbMSM) community AND at least one of the following:
    • Had a confirmed sexually transmitted infection within the last year
    • Have or are planning to have two or more sexual partners or are in a relationship where at least one of the partners may have other sexual partners;
    • Have attended venues for sexual contact (e.g., bath houses, sex clubs) recently or may be planning to, or who work/volunteer in these settings; or
    • Have had anonymous sex (e.g., using online dating/hookup apps) recently or may be planning to; and/or
    • Are a sexual contact of an individual who engages in sex work
  2. Individuals who self-identify as engaging in sex work or may be planning to, regardless of self-identified sex or gender
  3. Research laboratory employees working directly with replicating orthopoxviruses with an ongoing risk of exposure

Household and/or sexual contacts of those identified for pre-exposure vaccination eligibility in parts (a) and (b) above AND are moderately to severely immunocompromised (external PDF) or pregnant may be at higher risk for severe illness from a mpox infection and may be considered for pre-exposure vaccination and should contact their health care provider or public health unit for more information.

Moderately to severely immunocompromised household and/or sexual contacts must present with one of the following during their vaccine appointment:

  • A completed referral form (PDF file) from their health care provider; or
  • A current medication bottle or prescription receipt for a medication listed in Mpox Vaccine (Imvamune®) Guidance for Health Care Providers (external PDF), Table 2 List of Significantly Immunosuppressive Medications.
    • The prescription or medication bottle must include the:
      • client’s first and last name (must match a piece of identification); and
      • address and telephone number of the pharmacy that filled the prescription.
    • The prescription must have been prescribed or refilled within the past 6 months.
    • Active treatment with B-cell depleting therapies (monoclonal antibodies targeting CD19, CD20 and CD22) must have been completed within the last 12 months.

Imvamune® vaccine for Post-Exposure Vaccination

  • The provision of Imvamune® vaccine for post-exposure vaccination requires an assessment of the risk of exposure by Halton Region Public Health.
  • Post-exposure vaccination should be given within 4 days of exposure, but can be given up to 14 days after last exposure.
  • If a patient self-identifies as a high-risk contact of a confirmed or probable case of mpox, the community health care provider should contact the patient’s local public health unit for further assessment to see if post-exposure vaccination would be recommended.

Halton Region Public Health Sexual Health Clinics will be offering Imvamune® vaccine for pre-exposure vaccination by appointment only to individuals who meet Ontario’s current eligibility criteria (external link). Eligible individuals can call 311 to book an appointment; no OHIP card or ID is required.

If a patient has had a high or intermediate risk exposure to mpox, the community health care provider should contact 311 to request Imvamune® vaccine for post-exposure vaccination to be administered in the health care provider’s office. The provision of Imvamune® vaccine as post-exposure vaccination for high-risk contacts requires an assessment of the risk of exposure by Halton Region Public Health.

For further information please see:

Given the current epidemiology in Ontario, Imvamune® is being offered as a two-dose primary series, with at least 28 days between first and second doses for individuals currently eligible for pre-exposure and post-exposure vaccination.

Individuals who are household and/or sexual contacts of someone who meets pre-exposure vaccination eligibility AND are moderately to severely immunocompromised are also eligible to receive 2 doses of Imvamune® at least 28 days apart. For details of the definition of moderately to severely immunocompromised, please see Appendix A in the Mpox Vaccine (Imvamune®) Guidance for Health Care Providers (external PDF).

Moderately to severely immunocompromised individuals must present with one of the following during their second dose appointment:

  • A completed referral form (PDF file) from their health care provider; or
  • A current medication bottle or prescription receipt for a medication listed in Mpox Vaccine (Imvamune®) Guidance for Health Care Providers (external PDF), Table 2 List of Significantly Immunosuppressive Medications.
    • The prescription or medication bottle must include the:
      • client’s first and last name (must match a piece of identification); and
      • address and telephone number of the pharmacy that filled the prescription.
    • The prescription must have been prescribed or refilled within the past 6 months.
    • Active treatment with B-cell depleting therapies (monoclonal antibodies targeting CD19, CD20 and CD22) must have been completed within the last 12 months.

Please note, individuals who are eligible for pre-exposure vaccination and post-exposure vaccination who previously received an older generation replicating smallpox vaccine can be re-vaccinated. For individuals with a history of receiving 1 dose of a smallpox vaccine, only a single dose of Imvamune® is recommended.

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