Measles
Recently, measles cases have surged in Ontario, with particular focus in southwestern Ontario. These cases have primarily been among unvaccinated and partially vaccinated individuals. The following information is intended to provide an overview of key points for members.
Vaccination
Vaccination remains the best method of protection for this highly contagious infection, with two doses approaching 100 per cent effectiveness.
The routine immunization schedule for measles-containing vaccinations over an individual’s lifespan includes:
- Children: eligible for two doses (recommended at 12 months and 4-6 years)
- Adults 18 to 25 years old: eligible for two doses
- Adults 26 years of age and older: eligible for a single dose, although individuals born before 1970 are generally considered immune to measles
- Health-care workers: eligible for two doses
- All adults at higher risk of contracting measles, based on clinical judgement, such as post-secondary students and those traveling to or living in a region with a high measles rate: eligible for two doses
Individuals who are up to date with their vaccinations based on the recommendations above or who previously had measles are considered immune.
If an adult’s immunization records are unavailable, getting immunized with measles-containing vaccine is generally preferable to ordering a laboratory (serology) test to determine immune status. There is no harm in giving a measles-containing vaccine to someone who is already immune.
The measles vaccine is contraindicated in pregnant and immunocompromised individuals.
Outbreak recommendations
Modified vaccination schedules are recommended for patients who live in, travel to and/or spend time in regions with active measles cases and a higher risk of community exposure:
- Infants should receive their first dose of a measles-containing vaccine at six to 11 months of age. To ensure long-lasting immunity, they should receive two additional doses of a measles-containing vaccine after 12 months of age (three doses total). Infants under six months of age should not be vaccinated for measles.
- Children one to four years of age who have already received their first dose of measles-containing vaccine are encouraged to receive a second dose as soon as possible, provided it has been at least four weeks since the first dose.
- Adults 18 and older are recommended to receive a second dose of a measles-containing vaccine.
Health-care workers who have already received two MMR doses are not recommended to get a booster, since two doses have almost 100 per cent efficacy.
Note that not all areas of Ontario are in outbreak. Access the latest Measles Epidemiological Summary from Public Health Ontario to see the areas of the province at the highest risk.
Symptoms and screening
Patients with measles may present with:
- Fever
- Runny nose
- Cough
- Conjunctivitis
- Red maculopapular rash starting from the hairline and spreading downwards
- Pathognomonic enanthema, known as Koplik spots
As part of your regular screening process for patients presenting with the symptoms above, consider also asking about:
- Any known contact with measles case(s)
- Living in or recent history of travel to high-risk areas with recent case(s) of measles
- Immune status (unvaccinated or partially vaccinated for measles, or immunocompromised)
Patients who are suspected of possibly having measles should be given a mask and immediately isolated in an airborne isolation room with the door closed. Alternatively, put them in a single-patient room with the door closed.
Recommended PPE and precautions
Measles is an airborne virus, and the highest level of PPE is recommended:
- A fit-tested, seal-checked N95 respirator
- Gloves, a gown and eye protection may be added based on a point of care risk assessment
Only health-care providers with presumptive immunity to measles should care for patients with suspected or confirmed measles except in exceptional circumstances.
After the patient leaves the room, allow sufficient time for the air to change in the room and be free of respiratory particles before re-entering, which you can assume is two hours if air changes are unknown.
Individuals with suspected measles should be advised to isolate while laboratory results are pending. The local public health unit will contact them with further guidance. In the meantime, they should:
- Self-isolate from all public places including workplaces, schools and childcare
- Avoid contact with non-household contacts and high-risk individuals (including those who are pregnant, less than 12 months of age and/or immunocompromised)
- Advise any health-care settings in advance of their suspected measles diagnosis; if advanced notice isn’t possible, they should alert the facility immediately upon arrival
Refer to the OMA's What PPE to use in your community practice poster and Safely providing in-person care for community-based practices resource for PPE recommendations for respiratory illness, including measles.
Testing
Measles is diagnosed by molecular (PCR) testing using a nasopharyngeal swab or throat swab and a urine sample. Serology testing using a blood sample is also possible, but not essential, for diagnosis.
To avoid exposure to others wherever possible, collect samples in your office while the patient is already there. If you plan to send a patient for serology testing, consult with your local laboratory and public health unit ahead of time to ensure they can minimize exposure risk to the public.
For more information on measles diagnostic testing, refer to PHO’s measles: diagnostic PCR and measles: serology web pages.
Reporting
Suspected or confirmed measles is a disease of public health significance and must be reported as per Ontario Reg. 135/18 and amendments under the Health Protection and Promotion Act.
Contact your local public health unit immediately to report a suspected case of measles and to get guidance. Do not wait for positive test results to report.