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A researcher works with the experimental COVID-19 antiviral pill, Paxlovid, at a laboratory in Freiburg, Germany, on Nov. 16. The U.S. Food and Drug Administration on Dec. 22 authorized the pill for at-risk people aged 12 and over, a major milestone in the pandemic that will allow millions to access the treatment.HANDOUT/AFP/Getty Images

Health Canada is unlikely to approve until the new year an antiviral pill for COVID-19 that the United States has just authorized, meaning the medication may not be available here in time to mitigate the worst effects of the fast-moving Omicron wave.

The U.S. Food and Drug Administration granted emergency-use authorization on Wednesday to Pfizer Inc.’s Paxlovid, the first oral antiviral treatment for COVID-19.

The treatment regimen, taken over five days, reduced the risk of hospital admission or death by 88 per cent in the high-risk, unvaccinated participants of a clinical trial, Pfizer said when it released the final results of the study last week.

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Pfizer also said early lab studies indicated Paxlovid would work just as well against Omicron as against other variants of the coronavirus.

Health Canada received an application for the Pfizer pill on Dec. 1, according to Anne Génier, a spokeswoman for the regulator. However, she said by e-mail that Health Canada is still waiting for some information from Pfizer, “and timelines for a decision will depend on when all the necessary data have been submitted to Health Canada.”

Christina Antoniou, a spokeswoman for Pfizer Canada, said in a statement that the company’s “ongoing rolling submission for authorization to Health Canada is currently under review, and we are moving as quickly as possible in our efforts to get this treatment into the hands of patients.”

Pfizer has said early lab studies indicated Paxlovid would work just as well against Omicron as against other variants of the coronavirus.HANDOUT/AFP/Getty Images

The federal government announced earlier this month that it has signed a deal to buy one million courses of the medication, with the first shipments expected to arrive as soon as Health Canada gives Paxlovid a green light.

Ms. Antoniou said the deal includes quarterly delivery commitments, but wouldn’t say how many courses of treatment Pfizer has promised to Canada in the first quarter of 2022.

Ottawa has also agreed to purchase at least half a million courses of Molnupiravir, a Merck antiviral that cut the risk of hospital admission and death in COVID-19 patients by 30 per cent in a clinical trial. Health Canada has been reviewing Molnupiravir since August, and is awaiting more data from the drug maker before it issues a decision, Ms. Génier said.

Ottawa has agreed to purchase at least half a million courses of Molnupiravir, a Merck antiviral that cut the risk of hospital admission and death in COVID-19 patients by 30 per cent in a clinical trial.MERCK & CO INC/Reuters

When it comes to evaluating the new COVID-19 antivirals, “Health Canada should absolutely be stepping on the gas,” said Andrew Morris, an infectious-disease physician at Toronto’s University Health Network and a member of Ontario’s COVID-19 Science Advisory Table.

Dr. Morris said the regulator needs to move quickly – without cutting corners on its review – because Omicron is spreading much faster than its predecessors.

There are encouraging early signs from abroad that Omicron is more mild than previous variants, but its sheer transmissibility could still lead to enough severe cases to overwhelm hospitals, Canadian public-health leaders have warned.

As well, one of the few treatments approved for COVID-19 in Canada, a monoclonal antibody cocktail developed by the U.S. company Regeneron, doesn’t work against Omicron.

Monoclonal antibodies are lab-made versions of proteins that can fight off infections. They are given intravenously, and have to be administered early, before COVID-19 patients fall severely ill, to work well.

The Science Advisory Table on Wednesday updated its COVID-19 treatment guidelines to say that doctors should only prescribe a different monoclonal antibody, GlaxoSmithKline’s Sotrovimab, because it appears to be effective against Omicron, now the dominant variant in Ontario.

As the only monoclonal antibody that works against Omicron, Sotrovimab is now in high demand, especially in the United States. The Trudeau government announced in October a deal to buy 10,000 doses, but it’s not clear how many of those are available.

Zain Chagla, an infectious-diseases doctor at St. Joseph’s Healthcare Hamilton who oversees a pilot project that was administering the Regeneron cocktail, said his outpatient clinic has already switched to Sotrovimab.

People queue up for their COVID-19 vaccine booster shots at a clinic inside the Metro Toronto Convention Centre on Dec. 22. The Science Advisory Table says doctors should only prescribe GlaxoSmithKline’s Sotrovimab because it appears to be effective against Omicron, now the dominant variant in Ontario.STRINGER/Reuters

The Ontario government is planning to expand the monoclonal antibody pilot project to six more hospital sites in the coming days, according to Alexandra Hilkene, a spokeswoman for Health Minister Christine Elliott.

Dr. Chagla said that testing capacity is a major stumbling block to making the most of monoclonal antibodies and the yet-to-be-approved antivirals. In Ontario, Omicron is causing so many infections that testing appointments are hard to come by and results take days. Both treatments need to be administered as soon as possible after symptoms emerge.

“We may have to give up on testing every mildly symptomatic person,” he said. “We may need to do risk-factor-based testing in order to get people to get these drugs.”

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In Alberta, mobile paramedic teams began administering Sotrovimab in patients’ homes about a month ago.

Ilan Schwartz, a University of Alberta infectious-diseases physician, said Sotrovimab has been especially useful for transplant recipients on immunosuppressant drugs who tend not to derive much protection from vaccines. They also tend to watch carefully for symptoms of COVID-19, get tested at the first hint of symptoms, and call their doctors to seek treatment.

Unvaccinated people don’t necessarily behave the same way, which makes it more difficult to get monoclonal antibodies to them early enough in the course of the infection in time to make a difference. The same could be true of antivirals, even when they come in easier-to-give pills.

“Inherently that group is less closely connected to medical care,” Dr. Schwartz said of the unvaccinated. “[They’re] more reluctant to seek medical care, and so would be less likely to be identified at an early enough phase where they would qualify or benefit.”

British Columbia is tightening public health restrictions as it also plans to introduce enhanced rapid testing and booster shot programs to fight the highly contagious COVID-19 Omicron variant.

The Canadian Press

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