Over the past 50 years, the measles vaccine is estimated to have saved nearly 94 million lives.Jeff McIntosh/The Canadian Press
The date was Feb. 8, 1954 and young David Edmonston had an upset tummy.
Compared with other global events around that time – the death of Joseph Stalin, the advent of colour TV – the gastrointestinal woes of an 11-year-old in rural Massachusetts hardly seemed consequential.
But to Thomas Peebles, they hinted at a chance to make history. When the young physician-researcher at Boston Children’s Hospital learned of David’s symptoms– which soon included a telltale rash – he beelined for the boy’s boarding school, where a measles outbreak was under way.
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Dr. Peebles wanted three things from David: a throat-washing, some blood and a stool sample. But he also extended an invitation. “He asked if I would help the world,” David later recalled. “So I said yes, of course.”
Today, every Canadian child who gets a measles vaccine is injected with a weakened form of the virus that traces back to the “Edmonston strain” that Dr. Peebles collected that day. More than two millennia after a cattle pathogen spilled over into human populations, the virus that causes measles had finally been isolated from the blood of an American schoolboy. Within a decade, it would be harnessed into a vaccine.
Dr. Michael Kapusta inoculates children with the measles vaccine at St. Teresa’s school in Toronto on Dec. 13, 1965.James Lewcun/The Globe and Mail
The medical breakthrough heralded the modern era of vaccination. It gave the world a powerful defence against one of the most contagious diseases known to humankind. Over the past 50 years, the measles vaccine is estimated to have saved nearly 94 million lives.
And because the virus only circulates in humans, the arrival of an effective vaccine introduced a tantalizing possibility: eradication.
“Today we are on the threshold of eliminating another dangerous disease – measles,” U.S. health officials announced in 1967.
Six decades later, that threshold has yet to be crossed.
Measles remains very much a part of the human condition. According to latest estimates, more than 100,000 people died of measles in 2023, primarily children in lower-income countries.
This year has seen an alarming resurgence in countries where measles is considered eliminated, including Canada and the U.S., both of which are struggling to extinguish their largest outbreaks in decades.
There were signs from the start that the path to conquering the disease would be bumpy and meandering.
Public reception to the measles vaccine in 1963 was relatively muted compared with the jubilation and public weeping that erupted when an effective polio vaccine was announced, pediatrician Adam Ratner says in Booster Shots: the Urgent Lessons of Measles and the Uncertain Future of Children’s Health.
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“From the beginning, the announcement of measles vaccine availability was plagued by contradictions,” he wrote. “Inconsistent messages, unclear availability and limited public understanding of why one might want to vaccinate a child against measles in the first place … hindered the availability and success of the measles vaccine.”
Experts knew that one barrier to vaccination was the widespread belief that measles was a normal and ultimately harmless part of childhood. In reality, measles annually killed more Canadian children than polio, a disease that struck parents with terror.
(Today, one in every 1,000 children infected will die. Measles can also weaken the immune system, in addition to causing complications such as deafness, blindness or brain swelling.)
The first two licensed vaccines for measles were also less than ideal.
One, made with a “killed” or inactivated virus, was well tolerated but offered inferior protection (it would be taken off the market by the early seventies).
An electron microscope image of a measles virus particle.Cynthia Goldsmith/The Associated Press
The better-performing vaccine, made with a weakened version of the live virus, was prone to causing high fevers and even rash. These side effects could be mitigated with a second injection of a preparation made from donated blood plasma. But this was cumbersome and expensive, especially compared with the polio vaccine, which sold at just six or seven cents a shot.
“Sir, when is the measles’ vaccine going to be made available to the free immunization clinics?” a reader calling themselves “anxious mother” wrote to The Toronto Star in 1964. “We with large families feel the $10 charged by physicians is a little steep for each child.”
An answer came the following year, when Toronto launched a mass vaccination campaign – the first by a Canadian public health department, according to reports at the time.
Vaccinating became easier and more tolerable in the seventies, with the introduction of the combined measles, mumps and rubella (MMR) shot. This included an attenuated version of the live measles virus that minimized side effects.
But measles outbreaks continued, and health officials bemoaned Canada’s low vaccination rates. “Young families are no longer motivated by the memory of diphtheria and polio epidemics of the pre-immunization era,” lamented a report by the Ontario Council of Health.
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In the early eighties, Canadian public health departments envied their counterparts in the U.S., where the incidence rate for measles was six times lower, owing in part to laws that mandated vaccinations for school-aged children.
In 1982, Ontario and New Brunswick passed similar legislation (today, they remain the only Canadian provinces with such laws). In Ontario, the law gave rise to anti-vaccination groups such as the Committee Against Compulsory Vaccination. Within just two years, these organizations had successfully pressured the province into amending legislation to allow for exemptions based on conscientious objection.
Newspaper headlines from the decade reveal the fragility of every hard-won victory against the wildly infectious foe. “Measles in Canada drops to all-time low,” says a 1983 headline in The Globe and Mail. One year later: “Measles cases in 3 provinces at 5-year high.”
The mid-nineties introduced the two-dose MMR vaccination schedule. This paved the way for Canada to achieve a historic milestone in 1998: measles elimination, meaning it had been free of continuous transmission for more than 12 months. The virus that once infected up to 90,000 Canadians a year no longer circulated in this country.
But that same year delivered the biggest setback yet to global elimination efforts. The Lancet, one of the world’s most prestigious medical journals, published a fraudulent paper authored by the now-disgraced British scientist Andrew Wakefield that alleged a link between the MMR vaccine and autism. The paper was ultimately retracted 12 years later, and Mr. Wakefield was banned from practising medicine.
The damaging paper had landed at a pivotal moment, however, with the Internet providing a new and powerful substrate for disinformation to spread through.
“That definitely was the beginning of the modern era of anti-vaccine sentiment,” said René Najera, director of public health for the College of Physicians of Philadelphia and editor of the History of Vaccines project.
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The first two decades of this millennium saw periodic measles flare-ups in Canada ignited by importations of the virus by infected travellers. Then, starting in 2020, the COVID-19 pandemic interrupted routine vaccinations, eroded public health care infrastructure and gave rise to a powerful wave of mistrust against the medical establishment – ideal conditions for measles to stage a comeback.
In North America, this ancient virus is once again on the move. And it’s spreading through a world that bears little resemblance to the one Dr. Peebles asked young David to help.
Vaccines have become deeply politicized. Social media and influencers are spreading false or misleading information faster and farther than ever. The U.S. – once a global leader in public health– has a vaccine skeptic running its health department and dismantling the research ecosystem that once gifted the world its first measles vaccine.
“Measles is one of those diseases like smallpox that can be eradicated. A couple of generations of near 100 per cent vaccination and we would eradicate it, and then we can take it off the vaccine schedule and nobody has to worry about it,” Dr. Najera said.
“But, you know, that’s not where we are.”
