Open Letter: Vaccine-PLUS Strategy Needed for Measles Outbreaks
April 24th, 2025
To: The Provincial Government of Ontario
℅ Doug Ford, Premier of Ontario
Dr. Kieran Moore, Ontario Chief Medical Officer of Health
Sylvia Jones, Minister of Health
Paul Calandra, Minister of Education
David Piccini, Minister of Labour
Jill Dunlop, Minister of Emergency Preparedness and Response
Dear Premier Ford, Dr. Moore, and Hon. Ministers Jones, Calandra, Piccini and Dunlop:
We are writing on behalf of Ontario School Safety (OSS), a grassroots, fully volunteer organization dedicated to promoting the health and well-being of students, education workers, and families across Ontario. Once again, we urgently bring to your attention the escalating threat of measles outbreaks in Ontario and the need for an immediate vaccine-PLUS strategy, which includes cleaning indoor air to help curtail the spread.
As of April 17th, 2025, Public Health Ontario is reporting 925 measles cases in the province, more than five times the number of cases than the total number of cases over the last 12 years. Alarmingly, Public Health Ontario is also reporting breakthrough cases among individuals between the ages of five and 40+ who have two or more doses of the measles vaccine.
While vaccination remains the cornerstone of measles prevention through 95% herd immunity, there are several reasons why a vaccine-only strategy is not enough to curtail the spread at the rate needed in 2025:
Public Health Ontario reports that only 70% of seven-year-olds are considered fully immunized as of the 2023-2024 school year.
People living with certain disabilities, those living in remote or underserviced areas, and individuals facing socio-economic challenges can encounter significant barriers to accessing vaccination services.
Newcomers may also find it challenging to obtain accurate information about vaccines and vaccine-preventable diseases in their home language and to access a family doctor or other trusted healthcare workers.
Individuals with compromised immune systems or specific health conditions may have contraindications for immunization, rendering them reliant on herd immunity for protection.
As measles floats through the air and can linger in a space for up to two hours, we urge the Government of Ontario and Public Health Ontario to put equal focus on cleaning the air in places we inhabit the most, especially in schools and on school buses. Cleaning indoor air can reduce the amount of measles virus students, staff, and bus drivers inhale (which will, by extension, reduce the amount of measles virus in the community), while the province simultaneously works to increase vaccination rates to a level for herd immunity; clean air can also help reduce infections from other airborne pathogens (Strep, influenza, Covid-19, RSV, whooping cough, TB, the common cold, etc.) and reduce other recurrent health threats (like allergens, pollution, wildfire smoke).
There are several science-backed ways to improve air quality in schools and on school buses, many of which are readily available now and others that the Government of Ontario can make available quickly. We consider these the “low-hanging fruit” of a vaccine-PLUS strategy.
Following our “Investigating Indoor Air Quality at Your Child’s School” guide, which was reviewed and endorsed by the Ontario Society of Professional Engineers, this includes:
Ventilation - Opening windows, ensuring mechanical ventilation is running when the building is occupied, using the highest rated filters that can be accommodated (MERV-13, if possible), and regularly inspecting filters for proper fit and replacement.
Filtration - Turning on HEPA air purifiers and running them continuously; if noise is an issue (as it sometimes is in classrooms, depending on the purifier model), combine two or more units and turn them to a lower setting when the classrooms are occupied.
Additional measures that can be taken to make the air safer to breathe include:
Holding more events and assemblies outside.
Providing those who are unwell or have been exposed with the support/ability to stay home.
Holding a DIY air purifier workshop (great for a STEAM, life-skills, community service project) and placing them in all school spaces where people gather (gyms, libraries, cafeterias, bathrooms, offices, custodian workrooms, food services, classrooms and buses). These DIY air purifiers can be quieter than commercial devices, customizable for size, and cost-effective.
Encouraging and modeling the continuous wearing of a respirator mask. Respirator masks are a small “filter for the face” that can stop the spread of an airborne virus at its source and prevent people from breathing in airborne particles. They are a valuable and scientifically-supported community tool that, for the sake of each other’s health and futures, should be a welcome layer of protection. Please make CSA-approved CA-N95, KN95, and/or NIOSH N95 respirator masks free and available at all schools and on all school buses. Please encourage staff to model mask-wearing behaviour so that measles does not spread unnecessarily among them or among the students they serve.
Although taking these measures to clean indoor air is an immediate initiative to help reduce the spread of measles, we urge the Government of Ontario and Public Health Ontario to also engage in longer-term initiatives. Some of these longer-term initiatives include adopting ASHRAE 241 into Ontario’s Building Code, facilitating widespread public health campaigns about measles transmission and the importance of vaccination, creating a provincial vaccination database, as well as promoting a culture of shared responsibility to reduce the spread of measles and other viruses and bacteria.
We urge the Ontario government and Public Health Ontario to intensify measles vaccination campaigns while acknowledging the vital role clean indoor air plays in safeguarding the health of all Ontarians against preventable airborne illnesses, like measles, and begin educating on, and encouraging the use of, all the tools currently available to reduce transmission. If you would like to discuss these recommendations and use our wealth of accumulated knowledge, please reach out—Ontario School Safety is always ready to collaborate with you for the sake of the people, staff, and students of Ontario, so we can put an end to these preventable health threats and emergencies once and for all.
Yours truly,
Mary Jo Nabuurs
Spokesperson and Officer of Media Relations and Outreach
Ontario School Safety
Download the open letter in PDF format: