Measles has had a busy start to 2019.
In Vancouver this week, “several” measles cases were reported at local schools. The state of Washington declared a public health emergency in late January, responding to an outbreak that has infected 54 people so far.
The World Health Organization (WHO) even declared the anti-vaccination movement one of 2019’s top 10 health threats, saying that measles cases have risen globally by 30 per cent, though not all of these cases are attributable to vaccine hesitancy.
Measles is much, much less common in Canada than it was before the first vaccination was approved in 1963, but public health physicians are worried about the disease coming back.
Measles can be deadly
Measles was once a very common childhood disease, and most people who got it recovered completely.
Some didn’t though.
Measles-related deaths were very common in the early 1900s, according to the Public Health Agency of Canada. The government only started keeping track of the number of cases in 1924, but in 1926, 892 deaths were reported from measles.
Between 1969 and 1979, after the vaccine was approved, there was a total of 129 measles-related deaths. By the early 1980s, there were only one to three deaths per year. Recently, says PHAC, they’re unaware of any measles deaths in Canada.
But measles still kills people — around 110,000 people died from measles-related complications worldwide in 2017, according to the WHO.
It’s hard to estimate the exact mortality rate for measles in a developed country like Canada says Public Health Ontario, partly because we see so few cases, but the agency’s Dr. Natasha Crowcroft estimates that one out of every 3,000 to 5,000 children who get it will die.
“There’s nothing else where you would accept a risk of one in 3,000-5,000 of your child dying,” said Crowcroft, who is PHO’s chief of applied immunization research and evaluation.
“If you were going to Canada’s Wonderland, and they said, ‘It’s a really safe ride but every 3,000-5,000 rides, someone is going to die,’ nobody would get on that ride.”
The U.S. Centers for Disease Control has an even higher estimate: that for every 1,000 children who catch measles, one or two will die from it. Serious complications include encephalitis — a swelling of the brain that can result in death or brain damage — and pneumonia. A more common complication, ear infections, can lead to permanent hearing loss.
“This is a serious disease. It causes serious complications which ultimately can result in death,” said Dr. Gerald Evans, chair of the division of infectious diseases at the Queen’s University faculty of medicine.
And once you have measles, there’s not a lot you can do about it. “Other than the vaccine we don’t have a treatment for measles. So we don’t have antiviral drugs like we do for influenza and stuff like that. With measles, it’s really just supportive care.”
Measles is incredibly contagious
Unfortunately, measles is also “unbelievably easy” to catch, Evans said.
How easy? Look at something disease experts call the “basic reproduction number,” a measure of how infectious something is.
Influenza has a basic reproduction number of about 2, which means that every person who has the flu will likely give it to two other people.
Measles has a basic reproduction number of around 18.
“If I have measles and I walk into a room full of people who have not been vaccinated and never had measles themselves,” Crowcroft said, “on average I would infect another 18 people and each of those people would infect another 18 people.”
As one of the world’s most contagious diseases, measles spreads through the air, making it much easier to catch than say, HIV, which is only transmitted through certain bodily fluids. The virus can even remain hanging in the air long after the infected person is gone, she said.
So if someone with measles coughs in a room and leaves, and you go in two hours later, you might still catch their disease.
Measles is largely preventable
Fortunately, we have a measles vaccine and have for decades. And it works pretty well, conferring more than 95 per cent protection under the current two-shot regime, said Evans.
And despite what some high-profile figures have been tweeting this week, there’s no advantage to getting measles as a child, Evans said.
Catching measles is not a “natural” part of childhood, said Crowcroft.
“It gives you immunity naturally. It also naturally gives you brain damage. It also naturally kills you.
“It used to be quite natural for children to die all the time from all sorts of infectious diseases,” she said. “You could say it’s a part of childhood if you accept that it’s OK for children to die from infectious diseases in a situation where you could prevent them.”
The vaccine has been used for decades, so public health officials have good safety data on it, she added. Side effects are rare and treatable.
“Of all the things you have to worry about: getting lunch ready for tomorrow, getting your kids to school on time, global warming (…) vaccines are not one of the things you need to worry about,” she said.
It’s also important to get vaccinated to protect those who can’t: infants under one-year-old and people with compromised immune systems, she said.