Largest N.B. measles outbreak in decades pushing Canada's case count to 5-year high

A measles outbreak in New Brunswick is set to push Canada's annual case count to the highest it's been in five years, highlighting how infectious the disease is and how low vaccination rates have allowed it to take hold, says an immunologist.

Forty-four cases have now been confirmed in the province, all in health Zone 3, which includes Fredericton and parts of the Upper Saint John River Valley area, the Department of Health said late Wednesday.

It's the largest outbreak New Brunswick has on record in "several decades," said spokesperson David Kelly. The most recent outbreak was in 2019, when Zone 2, the Saint John region, saw a total of 12 cases over two months.

Asked how confident the department is that it will be able to keep the current outbreak under control, Kelly said in an emailed statement, "Public Health continues to closely monitor the situation and will inform the public if any new exposures occur."

All of the cases can be traced back to the initial one reported Oct. 24, involving a person who recently travelled internationally, but not all of them were necessarily in direct contact, as more spread would have occurred, he said.

They were all considered vulnerable because they either never had measles before, were unvaccinated or immunocompromised, said Kelly. Anyone born in 1970 or after who has not had two doses of measles vaccine and has never had measles is considered at risk, he noted.

More than 80 per cent of the infected people are 19 years old or under. Kelly did not provide a further breakdown, or the age of the the youngest case.

At least three people required hospitalization, but have since been discharged.

Most vulnerable children in decades

The New Brunswick outbreak, declared on Nov. 1, is part of a national surge, which reached 100 cases as of Nov. 2, and resulted in the death of child under five in Hamilton, according to the Public Health Agency of Canada.

The last time the country saw more cases was in 2019, when 103 cases were confirmed.

New Brunswick is doing the heavy lifting, which is "unusual in some ways because often we've seen measles outbreaks in large urban centres," said Dawn Bowdish, an immunologist and professor of medicine at McMaster University in Hamilton.

"But this just speaks to the fact that measles, once it gets into a population, can spread really, really quickly, and we have more vulnerable children than we've had in decades in Canada," she said.

Measles is the most infectious respiratory infection experts know of, said Bowdish, citing an investigation that found when an infected child got off a plane at an airport, an unvaccinated person three gates down got sick. "So that's just how contagious it is."

The virus is transmitted through the air or by direct contact with nasal or throat secretions of an infected person.

People at risk can be infected within as little as 15 minutes of exposure, according to the Department of Health.

It can also take up to three weeks for initial symptoms, such as fever, cough, sore and/or red eyes, runny nose or tiny white spots in the mouth, to appear, plus another three to seven days for the tell-tale red blotchy rash to develop on the face, body, arms and legs, so people can be contagious without knowing it and easily spread the virus to others.

Vaccination rates below target

Meanwhile, vaccination rates have fallen around the world because many countries have "either lost faith in vaccines or lost the political will to get people vaccinated," said Bowdish, which increases the likelihood of travellers bringing the virus back.

That's compounded by the fact the COVID-19 pandemic interrupted routine childhood vaccinations in Canada in 2020-21, she said, and the current lack of access to family doctors, which she described as being a "major driver" in low vaccination rates among children.

According to New Brunswick's 2023-24 school immunization report, among kindergarten students with proof of vaccination, 91.2 per cent have the required two doses of the measles, mumps and rubella, or MMR, vaccine.

That's down from 91.4 per cent in 2022-23 and below the national target of 95 per cent by 2025 to provide so-called herd immunity, where there's enough community resistance to a disease that it's unlikely to spread.

Asked what the province is doing to boost vaccination rates, Kelly said Public Health "regularly promotes the benefits of vaccination" through marketing campaigns, advertisements, media interviews and social media.

Bowdish believes outbreaks can help improve uptake, by shattering a "collective forgetfulness, where we don't remember just how bad measles is."

"It actually kills your immune cells" and can lead to other complications, she said, so children who get measles often get other infections and need other antibiotics or treatments afterward.

Measles can cause ear infections or pneumonia and can sometimes lead to swelling of the brain, which can cause seizures, deafness, brain damage or even death.

Vaccination is the best defence, said Bowdish.

Horizon Health Network has been holding a number of vaccination clinics in Zone 3. Upcoming clinics include:

• Fredericton Public Health office, 300 St. Mary's St., on Nov. 21 from 4:30 p.m. to 7:30 p.m., and Nov. 22 from 9 a.m. to 11:45 a.m., and from 1:15 p.m. to 3:30 p.m.
• Woodstock Public Health office, 200 King St., on Nov. 27 from 1 p.m. to 3:30 p.m.
• Stanley Health Centre, 69 Limekiln Rd., on Nov. 29, from 10 a.m. to noon and from 1 p.m. to 3 p.m.

Additional clinics may be added as needed, officials said.

Primary care providers and Public Health offices can also offer the vaccine to eligible New Brunswickers.

"The measles vaccine is considered very effective at preventing infection, is safe, and has been in use for more than 50 years," Kelly said.

He did not say how many doses the province has in stock, but did say there is an "adequate supply."

During the previous outbreak the province reserved its vaccine supply for those most at risk — infants and people who had direct contact with somebody with measles.

People who are unsure of their vaccination status, or that of their children, are urged to contact their health-care provider or local Public Health office, Kelly added.