Sporadic new mpox cases in Canada have experts urging vaccination ahead of summer

As the weather warms and Canadians start looking forward to summer travel and festivities, some experts are echoing a call made by health officials in Europe and the U.K. to be on the lookout in case mpox makes a return this summer.

Mpox — known as monkeypox before the World Health Organization announced that name would be phased out — made headlines last summer as unprecedented outbreaks surged in North America and in Europe. Cases sharply decreased in the fall, but since Europe’s outbreak was largely connected to summer festivals and music raves, health officials are warning that without awareness and more vaccine uptake, there could be a resurgence this summer.

On Friday, the European Centre for Disease Prevention and Control said in a statement that “there is risk of an increase in the coming spring and summer season due to festivities and increased holiday travel.”

Canada experienced a smaller outbreak compared to the tens of thousands who were infected in Europe last summer, with around 1,480 cases since May 2022.

But since the start of 2023, a handful of new cases have cropped up in Montreal and Toronto — a reminder that the disease is still circulating.

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“There is this concern that maybe there are some embers in the in the ash right now, that could spark new clusters if we're not careful,” Dr. Donald Vinh, an infectious disease specialist at McGill University Health Centre in Montreal, told CTVNews.ca in a phone interview.

“It may not be a huge wave, but still, there may be an increase.”

REMINDERS TO GET VACCINATED

Canada’s mpox epidemic peaked in late June and early July 2022, when there were around 25-30 new cases being reported every day, most within Ontario and Quebec. But this rapidly declined, with almost all cases ceasing by December 2022.

At the end of March, health officials in Montreal announced that new cases of mpox had appeared, with two laboratory-confirmed cases having emerged since March 17. Both are believed to be linked to travel to countries where local transmission is well documented.

According to the latest data from Public Health Ontario, as of March 28 there were 10 confirmed cases of mpox reported in Toronto in 2023.

“After our initial wave of impacts, for which there was a very aggressive and targeted public health and infectious disease response, mpox was under control in the major areas where it was emerging,” Vinh said.

“However, about a month ago, so mid-March or so, there were a few new cases of mpox. And my understanding was that there was some wastewater evidence in Toronto that was suggesting that mpox wasn't gone, it was still detectable in the wastewaters, which implies, of course, that there's some circulation in the community.”

Tens of thousands of Canadians got vaccinated against mpox in response to the initial outbreak last summer, with vaccine campaigns focused on at-risk groups. 

But the vaccine is meant to be doled out in two doses, with the second coming a month after the first, and many never received that second dose.

“In the Montreal cohort, we know that 54 per cent of the targeted population received one dose,” Vinh said. “However, only 24 per cent received the second dose.”

In Ontario alone, 37,470 doses of Imvamune, a smallpox vaccine approved for use against mpox, were delivered between May 4 and October 2022. Only 1,925 of these doses were a second dose, which is just five per cent.

“You need to have those two doses to have what we think is the maximum protection you're getting out of the vaccine,” Vinh said.

In February, Toronto Public Health posted a reminder for at-risk residents to make sure they got vaccinated against mpox in the wake of four new cases being reported within only 24 hours.

“After a period of no reported MPOX cases in Ontario, four new cases in a single day is concerning,” Dane Griffiths, director of the Gay Men’s Sexual Health Alliance, said in the news release. “Last summer, our community mobilized, got a first vaccine dose, and slowed the spread of MPOX. Let’s finish what we started and get the second vaccine dose, especially before travelling this winter.”

Mpox presents as a flu-like infection, often accompanied by lesions, and spreads through close personal contact with the infected lesions, skin blisters, body fluids or respiratory secretions of someone who is infected. It’s not a sexually transmitted disease, and anyone can contract it, but sexual activity is often a vector for transmission due to the close physical contact involved.

During Canada’s initial outbreak in 2022, the infection spread predominantly among men who had sex with other men, leading to strong vaccination campaigns driven by the LGBTQ2S+ community.

The new cases that have cropped up appear to be occurring in the same groups as before, Vinh said, meaning “there’s no new mode of transmission that's contributing to the recent cases.”

It’s reassuring in a sense, he explained, because it means that public health can utilize a similar community-focused approach, which was so successful before, in order to remind those at risk to be aware of the possibility of mpox.

“This should never be a disease that stigmatizes people. This is really an infection, like any other infection,” he said. “Education is our best weapon. Because if we are educated, we can then take educated measures to prevent it.”

WHY SUMMER COULD BE A CONCERN

Some viruses function better in the summer due to seasonality of the virus itself, Vinh said, which isn’t the case with mpox — it can be caught and spread at any time of the year.

The reason summer and spring bring a potential for increased spread is because of how our behaviour changes, he explained.

“Essentially, summer brings two things: warmth — so when you're warm, you tend to dress more appropriately for warm weather, shorts and T shirts, or that kind of stuff — and you also tend to be more jubilant, right, because it's the summer,” he said. “People want to go out, they want to do activities.”

And with mpox out of the headlines, many Canadians may not be aware that any risk still exists.

“I think the ‘out of sight out of mind’ can be very problematic, because the bottom line is this: it's not gone,” Kerry Bowman, an assistant professor and bioethicist in the Temerty Faculty of Medicine at the University of Toronto, told CTVNews.ca in a phone interview.

“A lot of people, as the summer of 2023 approaches, are saying ‘Hallelujah, and it's time to live again.’ And so I think people are very wise to continue the public health messaging.”

The answer isn’t to tell people to avoid all activities this summer that increase physical contact, as that isn’t realistic, Vinh said.

The first step is to ensure you’ve been vaccinated if you’re in an at-risk group.

“But there should also be a level of social protection through responsibility. In other words, you know, minimize the number of partners, be aware of who your partners are, and their health and that kind of stuff,” he added. “And so I think those two measures can go hand in hand.”

Vaccination isn’t a 100 per cent guarantee that you can’t contract mpox.

“At least in Montreal, one of the two (new) cases occurred in somebody who was doubly vaccinated, the other one was in somebody who was only singly vaccinated,” Vinh said.

But vaccination can mitigate serious disease, even if it fails to prevents transmission. And while the majority of mpox cases clear up without hospitalization or excessively painful lesions, minimizing the chance of them is important, he said.

“The virus can lead to quite painful and debilitating lesions, it can lead to hospitalizations, it can lead to super infections and other types of complications. For example, if the infection is present in the eye, it can lead to loss of vision.”

Bowman said he expects to see local public health outfits launch vaccine campaigns this spring to remind people to receive their second dose or to get vaccinated ahead of the summer season — but it could be a hard sell.

“I can see the challenge of it that after a three year pandemic, huge alarm bells for something that may be fairly muted could be worrisome,” he said.

He added that he believes public health should be providing resources to and working with LGBTQ2S+ organizations to get reminders out about vaccination, as it was leaders within these communities that helped to spur such a strong vaccination response in the summer of 2022.

“What tended to really, really turn things around was the gay community really kind of took over the situation, once the word was out that it was spreading through gay and bisexual networks,” he said.

From a public health standpoint, he’s also hoping that if we see more cases pop up, there will be more monitoring and clarity on cases to understand the actual prevalence.

Although Canada still has a dedicated epidemiological breakdown of mpox cases, a combination of data lag and differences in reporting can make it difficult to understand the scope.

The breakdown by province, which goes up to March 31, 2023, shows one new Alberta case and six B.C. cases of mpox in 2023 logged between Jan. 21 and Feb. 21, but it’s unclear if these are new cases that occurred in 2023, or older cases being added retroactively to the count. The breakdown also doesn’t reflect the recent Montreal cases.