Paxlovid still offers high-risk COVID-19 patients protection against hospital admissions, study says

A new Canadian study has found the antiviral drug Paxlovid continued to protect higher-risk individuals against COVID-related hospital admissions and death even after the Omicron variant was in circulation.

Much of the previous research into the effectiveness of nirmatrelvir–ritonavir, the two generic drugs sold under the brand name Paxlovid, was conducted before Omicron was in circulation and before the widespread availability of vaccines and boosters.

“It was important for us to assess what happened when it was used in the real world,” said Mina Tadrous, study co-author and scientist at ICES, a non-profit research organization in Toronto.

The new study, published Monday in the Canadian Medical Association Journal, suggests that higher-risk individuals – those 70 and older and/or those with underlying medical conditions – will continue to benefit from taking Paxlovid after testing positive for COVID-19 during the Omicron era. Newer variants that differ greatly from the original Omicron could make Paxlovid less effective, which worries more experts as the pandemic evolves.

The study used Ontario health data to compare a group of patients who received Paxlovid with a group that did not. The study found that 2.1 per cent of those who got the drug ended up in the hospital or died, compared with 3.7 per cent of those who did not get it.

The authors determined that 62 patients would need to be treated with Paxlovid to prevent one hospitalization or death, which Dr. Tadrous said is a reasonable number that justifies the use of this drug in higher-risk individuals. He highlighted that the drug is most effective at preventing severe outcomes in people at the highest risk, which is why it makes sense to continue applying restrictive criteria to ensure the right patients get it.

“If you used it in people who didn’t have risk factors, the number needed to treat would go higher,” he said.

The Therapeutics Initiative at the University of British Columbia, a group that conducts research on the effectiveness of drugs, found that in the real world, Paxlovid doesn’t appear to have any benefits when taken by lower-risk people. Expanding the eligibility criteria too widely exposes people unnecessarily to a drug that could have side effects and will cost the health system money, according to the group’s Therapeutics Letter, being published this week.

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Health Canada approved Paxlovid in January, 2022, for use in people who are at higher risk of severe COVID-19 infections. The antiviral medication is supposed to be taken within a few days of symptom onset in order to be effective. But for months, patients in many provinces reported difficulty in accessing the medication, with some suggesting the criteria were too strict and narrow.

In recent months, more provinces have begun allowing pharmacists to prescribe and dispense Paxlovid in order to ensure more people can get timely access to it. Ontario was one of the most recent jurisdictions to make that change last December.