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Middlesex-London Health Unit

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Mpox (formerly known as monkeypox)

Note: Consistent with the Ministry of Health, the Middlesex-London Health Unit will now refer to human monkeypox disease as mpox and the virus that causes mpox as MPXV.

Mpox is a rare disease that is caused by infection with MPXV. MPXV is a member of the orthopox virus genus related to smallpox. However, mpox has a similar but less severe clinical presentation and is less contagious than smallpox. Until recently, mpox was mostly present in Central and West African countries, with sporadic cases occasionally in travelers.


Mpox Vaccine and Eligibility

The Imvamune® vaccine is approved in Canada for protection against mpox. The vaccine contains modified virus and cannot make you sick. The vaccine can be used for protection against mpox before getting exposed to the virus (Pre-Exposure Prophylaxis – PrEP) or after being exposed (Post-Exposure Prophylaxis – PEP). It is not used as a treatment if you already have mpox. 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.

Who’s eligible for the vaccine?

The Imvamune® vaccine is available as a two-dose primary series, with at least 28 days between first and second doses for individuals eligible for pre-exposure or post-exposure vaccination.

  • Pre-exposure vaccination is when Imvamune® is administered before known exposure to the virus.
  • Post-exposure vaccination is when Imvamune® is administered for individuals who have had a high-risk exposure to a probable or confirmed case of mpox, or within a setting where transmission is happening.
  • Individuals who have been diagnosed as a confirmed case of mpox are not eligible for the vaccine.
  • If you think you have mpox, it’s important to isolate right away and contact a health care provider. Do not visit any mpox vaccination clinics.
  • If you have any COVID-19 symptoms and/or you are required to self-isolate, wait to get vaccinated.

Pre-Exposure Vaccination

Based on the Ontario Ministry of Health’s Guidelines, a two-dose primary series of Imvamune® is available to the individuals below.

(A) Two-spirit, non-binary, trans- or cis-gender, intersex, or gender-queer individuals who self-identify or have sexual partners who self-identify as belonging to the 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 hookup apps) recently or may be planning to; and/or
  • Are a sexual contact of an individual who engages in sex work.

(B) Individuals who self-identify as engaging in sex work or are planning to, regardless of self-identified sex or gender.

Household and/or sexual contacts of those identified for pre-exposure vaccination eligibility above AND who are moderately to severely immunocompromised (see Appendix A from the Ontario Ministry of Health’s Mpox Vaccine Guidance for Health Care Providers) or pregnant may be at higher risk for severe illness from a mpox infection may be considered for pre-exposure vaccine and should contact their healthcare provider (or their local public health unit) for more information.

Post-Exposure Vaccination

Anyone who self-identifies as a high-risk contact of a confirmed or probable case of mpox should contact their local public health unit to find out if post-exposure vaccination is recommended.

The first dose should be offered within 4 days (up to 14 days) from the date of the last exposure to individuals who are a high-risk contact of a confirmed or probable case of mpox. The second dose should be offered at least 28 days after the first dose.

Mpox Vaccination Clinics

Mpox vaccination clinics are being held at the Middlesex-London Health Unit inside Citi Plaza (110-355 Wellington St, London) on select days.

Appointments are required
To book your appointment, please call 519-663-5317.

How does mpox spread?

Mpox spreads between people primarily through direct contact with infectious sores, scabs, or body fluids. It also can be spread by respiratory secretions during prolonged, face-to-face contact. Mpox can spread during intimate contact between people, including during sex, as well as activities like kissing, cuddling, or touching parts of the body with mpox sores. At this time, it is not known if mpox can spread through semen or vaginal fluids.

Who is at risk?

Anyone who has had close, prolonged contact with someone who is infected with mpox or who have touched contaminated objects/materials (clothing, bedding, towels, eating utensil and dishes) are at risk of becoming infected.

What are the signs and symptoms?

Symptoms may be similar to smallpox but less severe. Factors such as age, type of exposure, compromised immune system, and previous immunity from smallpox vaccination can impact severity of symptoms. Most people experience mild illness and recover on their own after a few weeks. However, in some situations people may become very sick.

Symptom onset can take place anywhere from 5 to 21 days (commonly 7-14 days) after being exposed to the MPXV. Symptoms occur in 2 stages and typically last from 2 to 4 weeks.

In stage 1, symptoms may include:

  • fever
  • chills
  • swollen lymph nodes
  • headache
  • muscle pain
  • joint pain
  • back pain
  • exhaustion

In stage 2 of the illness:

A rash develops - usually within 1 to 3 days (sometimes longer) after the fever starts. The rash often starts on the face or extremities however it can affect other parts of the body, such as the hands, feet, mouth, and genitals. The rash usually lasts between 14 and 28 days and changes through different stages before finally forming a scab which later falls off.

Images of individual mpox lesions

To see images of individual mpox lesions, please visit the Government of United Kingdom's website at


Images of individual mpox lesions

Monkey rash and lesions

Image source: Government of United Kingdom

How is mpox diagnosed?

Mpox is diagnosed based on a combination of factors, such as:

  • signs and symptoms
  • laboratory testing
  • risk factors such as
    • exposure to a case
    • travel history

A diagnosis must be made by a healthcare provider. Swabs of affected tissues or sores should be taken.

What is the treatment for mpox?

Treatment involves supportive symptom management, including adequate nutrition and fluid intake. There is currently no specific treatment for mpox. In most cases, the disease is mild and self-limiting. In more severe cases, anti-viral medication used to treat smallpox may be prescribed. Previous vaccination for smallpox can provide some protection from infection with mpox or help reduce the severity of symptoms. In some cases, the vaccine for smallpox may be administered to close contacts for post-exposure prophylaxis.

Anyone who develops symptoms of mpox should be assessed by a health care provider as soon as possible.

How can we prevent infection?

As with any communicable disease, following basic individual public health measures can help prevent you from getting or spreading an infection.

  • get vaccinated, if you're eligible
  • stay home when sick or if you have exposed skin sores that may be caused by mpox
  • practice respiratory etiquette, including covering coughs and sneezes, and wearing a face mask
  • hand hygiene
  • practice safer sex
  • keep sores and wounds covered

You can further reduce your risk of becoming infected with mpox by avoiding close physical contact, including intimate contact, with an individual who is suspected or confirmed to have mpox.

Date of creation: June 21, 2022
Last modified on: August 30, 2023