B.C. expert explains how the COVID-19 antiviral pill works, who it works for

Posted January 17, 2022 5:05 pm.

Last Updated January 17, 2022 5:12 pm.

Now that Health Canada has approved Pfizer’s antiviral pill treatment for COVID-19, a Vancouver doctor explains more about how it works and who it will likely be prescribed to.

The authorization posted to the Health Canada website Monday morning says the treatment has been approved for adult patients with mild or moderate COVID-19 who are at high risk of becoming more seriously ill.

Medical Director of the Vancouver Infectious Diseases Centre, Dr. Brian Conway says clinical trials showed taking the medication within the first three days of infection considerably reduced the risk of hospitalization.

Canada received its first shipment of PAXLOVID to treat 30,000 people this Saturday. With PAXLOVID now authorized, distribution to provinces and territories will begin immediately. https://t.co/xSPksA0eQM pic.twitter.com/ly3EaxMtdO

— Health Canada and PHAC (@GovCanHealth) January 17, 2022

In order to be eligible, recipients must have a positive COVID-19 PCR test and be at a higher risk of being hospitalized.

“You have to have certain criteria to suggest that you are at higher risk of being hospitalized and others that could be you’re a little bit older, you have underlying heart disease or lung disease, or you are on medicines or have a condition that weakens your immune system,” Conway says.

Starting treatment early is crucial, according to Conway, who says the difficulty with access to testing could be a problem.

“The benefit of the medicine was only demonstrated in individuals who started treatment within three to five days at most of initially developing symptoms,” he says.

“If you cannot get a test result or the test is delayed beyond that five-day window, preferably the three-day window, you are not eligible to receive this medicine because we don’t know if it will work. It has only been demonstrated to work in this very specific setting and in this very specific population.”

In an update in December, Provincial Health Officer Dr. Bonnie Henry said COVID-19 testing across the province had reached capacity. Prioritizing PCRs for those who are most at risk — people 65 years and older, as well as those with underlying medical conditions — and that many people would likely be handed a rapid test to take home if they head to a facility.

According to Conway, it is most likely those who meet the criteria for the medication are also in the prioritized testing group.

In clinical trials, Conway says both the Pfizer and Merck antiviral medications proved to significantly decrease the risk of hospitalization.

“That’s the point of these medicines is to prevent people from requiring hospitalizations, and both were shown to be beneficial in this regard,” Conway said.

However, Conway adds that if the infected person does not have pre-existing conditions that put them at risk of being hospitalized, or the person is already hospitalized the medication has no benefit.

“In individuals who are too healthy and who are not at risk of hospitalization, the medicine is of no benefit. In individuals who are so sick that they now require hospitalization, the medicine is still of no benefit. It’s really in the middle for individuals who are at some risk of being hospitalized by underlying disease, or immune system impairment.”

He also says the medication is in no way a preventative treatment.

“It’s so tempting for people to say, I’m just going to take it to prevent myself from getting sick. First, it has never been demonstrated to be beneficial in that regard. Second, this may induce – if it used too broadly and incorrectly – the same way as bacteria get resistant to antibiotics this may produce resistance of COVID-19 and to these medicines that make them not useful going forward.”

Conway also stresses the antiviral medication is not a replacement for vaccination.

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