Canadian study finds Mpox vaccine 58% effective after one dose – The National

With just one dose Mpox vaccine A new Canadian study finds that it offers moderate protection against the virus. While “moderate” may not sound impressive, the researchers described the results as “excellent” and said more research is needed. Canadians at risk We will continue to receive vaccinations.

The study, published Wednesday, BMJwith one dose Modified Vaccine Ankara-Bavarian Nordic (MVA-BN) was 58 percent effective in preventing MPOX infection.

No randomized clinical trials have yet been conducted to test the effectiveness of the measles vaccine. Previous estimates based on observational studies suggested a single dose of the vaccine would be 36 to 86 percent effective, the study said.

“This is important because prior to the emergency use of this vaccine to reduce transmission during the global pandemic that has affected Canada, there had been no clinical trials to show how effective this vaccine would be in the real world during an epidemic,” said Dr. Sharmistha Mishra, co-author of the study and an associate professor in the University of Toronto's department of medicine.

“There was a lot of data on the safety of this vaccine but very little data on how effective it was. It was introduced in an emergency setting, but thanks to the data infrastructure and health-care system we have in Ontario, we're finally able to see how effective the vaccine actually was,” she told Global News.

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The vaccine is typically given in two doses, 28 days apart, to prevent MPOX, although the study did not investigate the effectiveness of the second dose.

of MVA-BN vaccine This is a smallpox vaccine that was introduced after the global smallpox outbreak was declared a public health emergency in July 2022.

In Ontario, the vaccine was initially rolled out in June 2022 as a post-exposure vaccination for high-risk contacts and a pre-exposure vaccination for gay, bisexual and other men who have sex with men, and sex workers at high risk of exposure, according to the study.

It has been approved as a two-dose series in Canada, but due to limited supply, Ontario initially adopted a one-dose strategy before switching to a two-dose program by September 2022.

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Before the pandemic, data on the efficacy of MVA-BN versus MPOX were limited. BMJ This study aimed to use targeted testing to more precisely estimate the efficacy of a single dose of MVA-BN against MPOX infection in a broader population.

To do this, the researchers looked at 3,204 vaccinated men and matched them with 3,204 unvaccinated controls. During the study period, from June 2022 to October 2022, 71 MPOX infections were diagnosed: 21 in the vaccinated group and 50 in the unvaccinated group.

“We wanted to find out how effective the vaccine, introduced in Ontario in 2022, was at preventing infection in people who are most at risk of contracting MPOX,” Mishra said. “We found that there was a 58 per cent reduction in risk of infection in people who were vaccinated.”

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While 58 percent efficacy may not seem high, Mishra said these results are still very promising and “fantastic.”

“This study showed that if something is as effective as 58% then it could have a very significant effect, especially when combined with other measures to reduce transmission and infection, especially during times of increased infection,” she said.

With MPOX infections on the rise again around the world, the researchers said these findings “strengthen the evidence that MVA-BN is effective in preventing MPOX infections and should be offered and made accessible to at-risk communities.”

On August 14, the World Health Organization (WHO) Declared MPOX a global public health emergency It is the second time in two years that the virus has spread to parts of Africa after causing an outbreak.

Around the same time, Ontario health officials warned A surge in MPOX cases in the region.

First identified in monkeys in 1958, MPOX (formerly known as monkeypox) was primarily confined to Central and West Africa and was transmitted through close contact with infected animals.

But that changed in 2022 as the virus spread rapidly among people across Europe, North America and other parts of the world.

Mpox is in the same virus family as smallpox and causes symptoms similar to smallpox, but generally milder. Common symptoms are a skin rash or mucous membrane lesions lasting 2-4 weeks, accompanied by fever, headache, muscle and back pain, low energy, and swollen lymph nodes. WHO report.

Mpox is caused by two different genetic variants: clade I and clade II. Clade II generally causes less severe infections and is responsible for the global outbreak that began in 2022 and is the variant circulating in Canada.

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Lineage I, the more worrisome lineage linked to more severe disease and higher mortality, is now spreading across Africa. This lineage was recently identified in sexual networks and has been reported in Kenya, Rwanda, and other parts of the world. Sweden — Countries where no cases of MPOX have been reported before.

The MVA-BN vaccine has only been studied in Ontario, where the Clade II strain of MPOX is present, but researchers hope it will also be effective against Clade I.

“We don't know if this vaccine will be as effective, but judging by the information that we have, we were faced with a similar situation in 2022. So, there's not much reason to think that it won't be as effective. But we don't have that information yet because the vaccine is still in phase one,” Mishra said.

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