Measles is back – here are five things you need to know
Measles has infected more than 2,500 people across Canada this year, including 12 in B.C. Here are five things UBC experts say you need to know.
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In what is the largest outbreak of the disease in decades, measles has infected more than 2,500 people across Canada this year, including 12 in B.C.
The Public Health Agency of Canada warns that by fall, measles may no longer be considered eliminated in the country – for the first time in 30 years.
Here are five things UBC experts say you need to know to protect yourself and your loved ones.
Measles is up to six times more transmissible than COVID-19.
Measles is uniquely dangerous, says Dr. Manish Sadarangani, UBC associate professor of pediatric infectious diseases and director of the Vaccine Evaluation Center at the BC Children’s Hospital Research Institute.
The disease is mainly spread through respiratory particles, and can linger in the air for up to two hours after an infectious person has left a room. In an unvaccinated population, each person infected with measles spreads the virus to an average of 18 others.
“That’s around six times the rate for COVID-19 — measles is one of the most contagious pathogens on the planet,” says Dr. Sadarangani.
There is no cure.
There isn’t a dedicated antiviral therapy available to treat measles. This fact is surprising to many who assume that all infections have a treatment, says Dr. Kyla Hildebrand, UBC clinical associate professor and division head of pediatric immunology.
However, if an unvaccinated person has been exposed to measles, they may be given a dose of the MMR (measles, mumps and rubella) vaccine within three days of exposure.
“Once illness occurs, there’s nothing that’s specifically going to cure the infection or improve the outcomes of the infection,” says Dr. Hildebrand. “Children or infants are more likely to develop severe infections and complications, which is why it’s so important to protect them through vaccination at the earliest opportunity. For children who are too young to be vaccinated, we can protect them through high levels of vaccination in the community, good hygiene practices, and limiting their exposure during periods of an active outbreak.”
Measles can cause “immune amnesia.”
Because the measles virus attacks your body’s own immune cells, including cells responsible for recognizing pathogens, it can erase up to 70 per cent of your previously acquired immunity to other pathogens.
“We have very clear proof from numerous studies that, after a measles infection, your immune system is suppressed for weeks to months,” says Dr. Sadarangani. “Some have suggested it may last up to two years.”
So even if you’ve recovered from measles, you’re at increased risk of contracting other illnesses — including those you’ve fought off or been vaccinated against, such as COVID-19 or the flu.
Measles can cause serious brain damage — even decades after an initial infection.
In about one in 1,000 cases, measles causes brain inflammation, called measles encephalitis, which can lead to serious brain damage, deafness or even death.
More rare is a progressive and fatal brain condition called subacute sclerosing panencephalitis (SSPE), which typically surfaces around 10 years after a person is infected. It can occur in up to one in 5,000 unvaccinated people infected with measles — but this number goes up to about one in 620 for infants under 15 months.
“It’s just very sad because it’s invariably fatal and there is no treatment or cure,” says Dr. Sadarangani. “The tragedy is that it is completely avoidable through vaccination and high vaccination rates.”
At least 95 per cent of the population must be vaccinated against measles for herd immunity.
When vaccination rates reach 95 per cent or higher, measles can be kept at bay through herd immunity, or the point where so many people have immunity that the disease cannot easily spread through a community. One dose of the MMR vaccine given at 12 months is 85 to 95 per cent effective at preventing measles. A second dose, typically given between 18 months and six years of age, brings protection up to 99 per cent.
Currently, B.C. vaccination levels are at their lowest in 20 years, with only 72 per cent of seven-year-olds in B.C. fully vaccinated against measles in 2023. In some areas of the province, rates have fallen below 65 per cent. That leaves those who can’t get the vaccine, including infants and pregnant or immunocompromised people, at risk.
“The MMR is a safe, extremely effective vaccine, and for almost everyone will give lifelong protection,” says Dr. Sadarangani. “Being fully vaccinated is the best way to protect yourself, your family and vulnerable members of our community. Vaccines save lives.”
Interview language(s): English
