Who can expect to get the COVID-19 antiviral pill in B.C., and how many will be available?

There's another tool in the fight against COVID-19 and B.C.'s top doctor said it will help prevent more serious illness if it's given to people early on.

Health Canada authorized the use of Pfizer's COVID-19 antiviral treatment Paxlovid Monday, and it's the first oral and at-home prescription medication to be cleared for use in the country.

In a news conference Tuesday, Dr. Bonnie Henry said the antiviral treatment is designed specifically for individuals at the highest risk of developing more severe illness and ending up in hospital.

"It includes those people in our community who are over age 70, clinically extremely vulnerable, immune compromised and for younger people who have additional medical conditions and don’t have the protection of vaccines."

Henry said B.C. can expect a limited supply of 4,000 treatment doses within the next few weeks.

The prescription-only medication must be started within five days of the onset of symptoms.

Henry added that the province is working with its clinical care advisory team to distribute the treatment where it can be the most effective.

"This is very good news. It's not going to change the trajectory of our pandemic right now but it's another tool to help those people who are more at-risk of ending up in hospital," she said.

University of British Columbia associate professor and drug safety researcher Mahyar Etminan said the treatment should not be viewed as a magic bullet.

"We don’t really have any data on children or healthy adults," he said. "So primarily, it was studied in adults who had COVID symptoms and had one other medical condition."

Etminan said the efficacy numbers being shared by the company for the treatment also need to be put in perspective.

"Unfortunately, the way they presented the data is this relative risk reduction metric, which tends to sort of overestimate the efficacy," he said, and noted Pfizer has reported an 88 per cent reduction of either hospitalization or death relative to the placebo group.

"In absolute numbers, it’s about a six per cent benefit...if 16 such participants took the drugs, one would benefit."

Etminan said roughly a thousand adults were part of the Pfizer study that received the antiviral combination, which helps prevent the replication of COVID in the body. He said a similar number were given a placebo.

"It’s also important to know that the data we have is data provided by the company," he said. "We still don’t have any peer-reviewed data from this study."

Etminan said based on the available data, "it seems like it should really be intended for adults who are at a high-risk of morbidity or dying from COVID."

"It comes down to risk versus benefits," he said. "It seems from the data we have that that sort of demographic would, right now at least, benefit the most from this drug."

Two additional vaccines, Medicago and Novavax, continue to be under review by Health Canada.

"We were hoping (Novavax) would be approved sometime in January, but it looks like it's more likely to be in February and Medicago may be as early as the end of January or February," Henry said.

"So I think that's important for those people who have made that determination that the mRNA vaccines that we have, and are holding out for something else. It's not going to be available to help you through this wave. But it is an additional option that will be coming, we hope, in the near future."