Public health, buy-in from gay and bisexual men helped get Canada’s mpox outbreak under control
An aggressive public health response and immediate buy-in from men who have sex with men — the group most affected by the outbreak — has helped to contain mpox in Canada, public health doctors say.
High vaccination rates and a change in behaviour — mostly among gay and bisexual men — has all but eliminated the viral disease formerly known as “monkeypox” since cases peaked during the summer.
“It is a remarkable story of success in an epidemic that was completely unpredicted and had significant global spread,” said Zain Chagla, an infectious disease physician and professor at McMaster University.
“The community was really leveraged to protect its own and did a remarkable job of reaching the networks that it needed to reach that typical public health officials could not.”
Mpox is a viral disease closely related to smallpox that is spread through close physical contact and can jump from animals to humans.
Most common in central and western Africa, mpox is found only occasionally elsewhere in the world. But in early May, several outbreaks appeared concurrently in non-endemic countries, such as Canada and the United States, for the first time.
Although gay men are not especially predisposed to contract the virus, roughly 99 per cent of cases recorded in Canada were among men, most of them gay or bisexual, the Public Health Agency of Canada said at the peak of the outbreak.
After a steep increase in total cases from May through the end of August, Canada’s mpox case count has since plateaued.
Because so few Canadians are now getting infected with mpox, some provinces have stopped providing routine updates on the disease. The Public Health Agency of Canada now considers current mpox levels to be “low.”
That reversal is due to a range of factors, Chagla said. First, mpox spreads through prolonged close contact and is therefore easier to control through contact tracing and isolation than more transmissible diseases, such as COVID-19.
Second, most governments already have stockpiles of smallpox vaccine on hand to guard against a chance outbreak or the threat of bioterrorism. The vaccine, called Imvamune, had been approved by Health Canada already when mpox cases began to appear here and could be put to immediate use.
Finally, an extensive public health response — which leaned heavily on men’s sexual health groups — convinced gay and bisexual men to get vaccinated, limit their sexual contacts and isolate at the onset of symptoms.
“There was a very early and aggressive focus on communities at risk and an early and significant focus on partnerships in that community to make sure that education, messaging, help counselling — all of that was bilateral,” Chagla said.
Dane Griffiths is director of the Gay Men’s Sexual Health Alliance, a Toronto-based sexual health promotion organization. He said he first learned about mpox following reports in May that cases had been discovered in western Europe.
Less than one week later, officials reported that Canada’s first mpox cases had been found in Montreal.
The alliance responded by developing a dedicated mpox webpage, running an information campaign across several social media platforms, designing resources for clinical care settings and collaborating with summer festivals, such as Toronto Pride, to raise awareness about the risks for those in attendance.
Griffiths said the alliance could lean on its existing network to spread public health messaging “directly to the community” facing the highest risk.
“I think we really took the advice of health care officials and community representatives very seriously,” Griffiths said. “And vaccination rates were exceptionally high.”
Although the percentage of gay and bisexual men in Canada who received the mpox vaccine is difficult to estimate, the Public Health Agency of Canada said in an email to CBC that vaccination clinics have administered 111,520 doses of the Imvamune vaccine as of Nov. 13, 2022.
A full series of Imvamune is two doses, but due to limited availability early in the outbreak, most high-risk people were encouraged to get just one.
Griffiths said now that the outbreak is more contained, the alliance’s priority is to encourage people who have received their first dose to top up their vaccination.
Outbreak ‘receding’ globally
Rosamund Lewis, technical lead for mpox at the World Health Organization, said the state of Canada’s outbreak is similar to outbreaks in the United States and some European countries. While new cases continue to pop up, the global total is declining rapidly.
“It means that the outbreak is receding,” Lewis said. “It’s self-contained.”
Lewis said Canada’s outbreak followed a “classic bell curve,” with a rapid rise in cases through the summer, followed by a brief peak and a sharp decline since.
“Low level circulation” likely persists in Canada, Lewis said, with small clustered outbreaks going unreported.
Although some World Health Organization officials have said it is possible to eliminate mpox in Europe, the disease is unlikely to be completely eliminated worldwide.
Christopher Labos, a Montreal-based cardiologist with a degree in epidemiology, said the presence of an “animal reservoir” means the virus could always jump back into humans — even if cases drop all the way to zero.
Currently, outbreaks are confined largely to African countries where cases are driven by a different strain than the one found in Canada.
Chagla said the continued presence of cases overseas underscores the need for global vaccination efforts to help prevent future worldwide outbreaks.
“This may not be the last [mpox] event we see,” he said.