How does Pfizer's COVID-19 pill work and who will get it?
CBC
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Now that Health Canada has approved Pfizer's COVID-19 therapeutic Paxlovid for use in people 18 and older, CBC News has been receiving questions about how it works and what its limitations are.
For starters, it's an oral antiviral treatment. In other words, pills that help you fight off the symptoms of COVID-19.
But here's a closer look at the ins and outs of the treatment.
Paxlovid consists of two antiviral drugs packaged together: nirmatrelvir and ritonavir.
Patients take three pills twice a day: two of nirmatrelvir and one of ritonavir. In total, the full course of treatment requires you take 30 pills over the span of five days.
Nirmatrelvir is a new drug developed by Pfizer-BioNTech, while ritonavir is an existing drug often used in the treatment of HIV/AIDS.
The two drugs work together, health experts say. Nirmatrelvir does the heavy lifting by hacking the virus's ability to replicate and multiply, while ritonavir acts as a sidekick to nirmatrelvir, enabling it to remain in the body longer.
Paxlovid is something called a protease inhibitor, explained Dr. Isaac Bogoch, an infectious diseases specialist at Toronto General Hospital.
"It stops the virus from dividing by blocking a part of its life cycle," he said, noting this allows your immune system to fight off the virus a lot easier.
But it's crucial to start treatment soon after infection, Bogoch said, "to really nip it in the bud early."
According to immunologist Dr. David Burt, who is also a member of Toronto's Black Scientists' Task Force on Vaccine Equity, the only drawback with these types of treatments is a "very narrow window of opportunity" before the drug loses its effectiveness.
When taken within five days of infection, Pfizer's clinical trials showed that the drug reduced risk of hospitalization or death by 85 per cent.
Canadians will need a prescription to get Paxlovid, according to Health Canada.
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