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Targeting monkeypox vaccine to high-risk areas 'reasonable,' says doctor

Canada won’t conduct mass vaccinations for monkeypox and instead will take a targeted approach, deputy chief public health officer Dr. Howard Njoo said Thursday.
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This 2003 electron microscope image made available by the Centers for Disease Control and Prevention shows mature, oval-shaped monkeypox virions, left, and spherical immature virions, right, obtained from a sample of human skin associated with the 2003 prairie dog outbreak. (Cynthia S. Goldsmith, Russell Regner/CDC via AP)

Canada won’t conduct mass vaccinations for monkeypox and instead will take a targeted approach, deputy chief public health officer Dr. Howard Njoo said Thursday.

The Public Health Agency of Canada confirmed 26 cases in Canada Thursday — 25 in Quebec and one in Ontario — up from 16 on Wednesday. That number is expected to rise as the National Microbiology Laboratory continues to test samples from multiple jurisdictions.

At a news conference, Njoo said the decision not to have a mass-vaccination campaign followed discussions among all chief medical officers of health in Canada.

He said limited shipments of MVA-BN vaccine — also known as Imvamune, Imvanex or Jynneos — from Canada’s National Emergency Strategic Stockpile are being offered to jurisdictions that require a targeted response.

Developed for smallpox, the vaccine was approved in 2019 for use in preventing monkeypox, which is in the same virus family, according to the World Health Organization. The original smallpox vaccine is no longer available to the public since vaccinations ended in 1980 after the disease was eradicated.

About 1,000 doses of Imvamune as well as antivirals have been shipped to Quebec for high-risk individuals. Both are authorized by Health Canada.

Multiple cases of human-to-human transmission of monkeypox have been identified in at least 20 “non-endemic” countries, those outside of Africa. The World Health Organization said it is working with all affected countries to enhance surveillance and provide guidance on how to stop the spread and care for those infected.

Njoo said cases of monkeypox have been identified in other regions of the world in the past, but never before in Canada.

Monkeypox is spread through close skin-to-skin contact or via clothes, furniture or utensils contaminated by weeping pustules. Unlike the highly transmissible Omicron variant of COVID-19, which is airborne, monkeypox is spread through large droplets, so masking would help prevent transmission, said Dr. David Forrest, an infectious disease and critical-care physician at Nanaimo Regional General Hospital.

Forrest said Canada’s approach to vaccination is “reasonable,” adding in B.C., simple public-health measures such as avoiding close contact will prevent a lot of transmission.

The strain of monkeypox circulating is not the serious strain found in parts of Africa, which causes fatalities in 10 per cent of cases. Still, Forrest said with any such virus, there is always concern for vulnerable populations, including the elderly.

“So I think while there’s not a reason to panic, we want to contain the spread of monkeypox so it doesn’t become a problem in vulnerable populations.”

Vaccinations can prevent disease if given within days of contact, said Forrest, noting the incubation period for the monkeypox virus can be up to three weeks. “So there’s an opportunity for the immune system to deal with this virus before it causes disease,” he said. “That may be the role of vaccination rather than vaccination of the population at large.”

Forrest said until now, any cases of monkeypox have usually been related to travel to endemic areas, primarily Africa, and no human-to-human transmission of significance has been documented.

“So this is unusual and clearly this is pandemic,” said Forrest. “I don’t think the WHO has declared a pandemic but, effectively, there’s transmission in communities worldwide so it is, really.”

The national laboratory is completing whole genome sequencing — an enhanced fingerprint analysis — on Canadian samples of monkeypox to help experts understand the chains of transmission occurring in Canada, said Njoo.

So far in Canada, the spread has mainly been between people in intimate sexual relationships, but it’s not a sexually transmitted disease and transmission is through close contact.

Amara Adina of the Victoria branch of Passport Health, a travel medicine and immunization service, said she has received calls from travellers asking if they can get the smallpox vaccine.

“I’ve been getting a lot of calls like that,” said Adina. “They call specifically for the smallpox vaccine.”

Passport Health offers common travel vaccines and speciality immunizations. It does not offer a smallpox vaccine.

The B.C. Centre for Disease Control said monkeypox vaccine is “not available at this time in sufficient supply to use for a large-scale immunization program including as a travel vaccine.”

ceharnett@timescolonist.com