Health Canada has authorized the use Paxlovid, Pfizer's antiviral treatment for individuals with mild to moderate COVID-19, who are at high risk of developing serious illness.
This is the first authorized COVID-19 therapy that can be taken at home, instead of being administered at a hospital or healthcare setting.
The treatment consists of two tablets of nirmatrelvir and one tablet ritonavirof that are taken together twice per day for five days. Patients should start the treatment as soon as possible after a COVID-19 diagnosis and within five days of the onset of symptoms.
At a press conference on Monday, Dr. Theresa Tam, Canada’s chief public health officer, said if a PCR test is not available or if the result will not be available until more than five day from the onset of symptoms, a rapid antigen test can be used.
Dr. Supriya Sharma, chief medical adviser with Health Canada, added that a positive result on a rapid antigen test is "very accurate."
Dr. Tam did say that, particularly related to the limited tests available in several parts of the country, there will be some "key operational considerations on the ground" to effectively get this treatment to Canadians.
How the new drug will be distributed
At this point, allocation of Paxlovid will be deployed to provinces and territories on a per capita basis.
Canada's first shipment is 30,000 treatments with 120,000 treatments arriving between now and the end of March. Canada has procured one million doses with an option to procure another 500,000.
Information submitted to Health Canada from Pfizer found that Paxlovid reduced the risk of hospitalization and death caused by COVID-19 by 89 per cent when the medications were started within three days of the onset of symptoms, and by 85 per cent when started within five days on the beginning of symptoms.
Paxlovid can cause interactions with other medications that can decrease drug effectiveness or possibly cause a more serious effect, in some cases.
Some interactions with Paxlovid include medicines used to treat erectile dysfunction, medicines used to lower blood cholesterol, medicines used to treat depression, medicines used to treat AIDS and some heart medicines.
Dr. Tam added that highest risk groups should be prioritized, including individuals who are moderately to severely immunocompromised who are not expected to mount an adequate response to SARS-CoV-2 infection, regardless of their vaccination status.
"We know that the unvaccinated are at higher risk of getting severe outcomes and getting hospitalized," Canada's chief public health officer said.
"In Canada, we treat people as they are and according to what healthcare needs they may have," Jean-Yves Duclos, Canada's health minister said at a press conference on Monday afternoon. "That’s what doctors and nurses do every day, they don’t ask questions about people’s choices or people's human nature, they look after people, they care for people."
"This being said, a drug is a treatment. It’s much better not to have to be treated and the best way not to have to be treated is to be vaccinated."
Additionally, individuals 80 and older whose vaccinations are not up to date should be prioritized, as well as individuals 60 and older who live in underserved rural or remote communities, residing in a long-term care setting or those in First Nations, Inuit and Metis communities whose vaccinations are not up to date.