Province to offer second vaccine dose

Ontario will be administering second doses of the monkeypox vaccine to those at highest risk of contracting the disease, in the wake of new recommendations from a federal expert panel.

The Imvamune vaccine was approved for use by Health Canada as a two-dose vaccine, given 28 days apart, but until now most individuals at high risk only received a first dose, mainly due to the limited supply.

The National Advisory Committee on Immunization (NACI) recommended in an updated guidance document released Friday afternoon that those at highest risk should receive the two doses “when vaccine supply is adequate.”

While the national supply remains limited, NACI is also recommending that those second doses can be administered in such a way that only one-fifth of the vial is used per person.

The rollout of second doses in Ontario is expected to happen soon.

Ontario’s Ministry of Health “is reviewing the NACI guidance and will work with local public health units on administering second doses,” the ministry told the Star.

Individuals at highest risk include men who have sex with multiple male partners, as well as sex workers and staff in “sex-on-premises venues,” NACI said.

The number of weekly reported cases of monkeypox during this year’s unprecedented global outbreak continues to decline, the director general of the World Health Organization said last week at a media briefing.

There have been 667 cases of monkeypox reported across Ontario, all but five of them reported in men.

Symptoms of monkeypox can include fever, swollen lymph nodes and painful lesions. Most people recover within a few weeks without treatment, but infections can lead to hospitalization.

The NACI guidance document says its recommendations are based on factors including the epidemiology of the ongoing Canadian and international outbreaks, the growing evidence of the level of protection provided by the vaccine and the current and projected supply.

A representative from NACI was not available for an interview Monday.

Anecdotally, there have been a few mild “breakthrough” cases of monkeypox in individuals who received one dose of the vaccine, said Toronto infectious diseases physician Dr. Isaac Bogoch.

“You probably get better protection by having two doses versus one, and I’m totally speculating, but we’ll probably see fewer breakthrough cases with two rather than one,” said Bogoch.

“Let’s nip this in the bud … We have the tools and the capabilities to eliminate monkeypox in Canada, and this will help with that.”

Bogoch said the outbreak is “in significant decline” in Canada.

“Cases are very low right now, (but) it’s not gone,” he said.

“I think we have to be aware that we may see imported cases from other parts of the world where monkeypox was previously not found, but, in terms of new cases in Canada, we’re in a much better place now than where we were, for example, in July.”

In Canada, the vaccine is currently injected “subcutaneously,” meaning in the fatty tissue just under the skin.

NACI is recommending that second doses can be administered as an “intradermal injection,” meaning between the layers of the skin, which requires about one-fifth of a dose.

An intradermal dose “is expected to generate a similar immune response to a full dose administered subcutaneously,” NACI said. “It may take time to train immunizers in the intradermal technique, which can be done while first doses are rolling out.”

The recommendation does not apply to individuals at high risk who are also immunocompromised, who NACI says should be prioritized to receive two doses at least 28 days apart.