Pfizer’s Paxlovid, which has just been approved in Canada, is the most effective of the current treatments against COVID-19, according to a new Montreal study. But it is not the cheapest. Analysis of the treatments offered and their effectiveness.
Posted at 12:00 a.m.
“With Paxlovid, we have to treat 24 patients to avoid hospitalization,” explains Todd Lee, internist at the Research Institute of the McGill University Health Centre. He is the lead author of a study published January 19 in the journal Open Forum Infectious Diseases. “With fluvoxamine, we have to treat 80 patients, but the cost is 10 times lower. »
For a patient, taking Paxlovid reduces the risk of hospitalization more than fluvoxamine, a generic antidepressant. Clinical trials on fluvoxamine are not complete, but are nevertheless promising, nuances the Dr Lee. The MUHC originally participated in clinical trials of fluvoxamine to prevent hospitalization in patients with COVID-19, but had to discontinue participation due to recruitment issues. “Ontario has included fluvoxamine in its treatment recommendations, but more on the real effectiveness will be known with other ongoing studies,” says Dr.r Lee. In general, the published studies with the drugs to be given in an outpatient setting relate to non-vaccinated people. The analogy is made for vaccinees, without randomized trial data. »
High cost
Big catch: Paxlovid costs $12,720 per hospitalization averted, compared to $1,122 for fluvoxamine. Molnupiravir, an antiviral similar to Paxlovid – but developed by Merck – meanwhile requires 50 treated patients to avoid hospitalization, at a cost of $35,000 per hospitalization avoided. Molnupiravir is authorized in the United States, but not yet in Canada.
Why not calculate the cost per death avoided? “The studies use hospitalization, because otherwise, there would be far too many participants in clinical trials, explains the Dr Lee. In general, the risk of hospitalization fairly well reflects the risk of death. »
The analysis of Dr Lee postulates a 5% hospitalization rate among all infected patients. Importantly, the analysis depends on the treatment indications used in the clinical trials.
If we reserve Paxlovid for those most at risk, the number of patients needed to treat to avoid hospitalization will be lower.
The Dr Todd Lee, internist at the Research Institute of the McGill University Health Center
Pfizer’s clinical trials of Paxlovid involved patients with at least one serious risk factor for COVID-19, such as obesity, age or heart disease. But in Quebec, for the moment, only severe immunosuppressed can receive it.
The study also looks at colchicine, a generic anti-inflammatory that raised a lot of hopes in 2020, before obtaining disappointing results in a clinical study led by the Montreal Heart Institute. To avoid hospitalization with colchicine, 91 patients need to be treated at a cost of $3,333, according to Dr.r Lee, who points out that the results with colchicine are not statistically significant.
Monoclonal antibodies
Monoclonal antibodies and Remdesivir, two treatments little used in Canada, are the most expensive, with costs per hospitalization averted exceeding $50,000. On the other hand, they are relatively effective, with less than 30 patients treated per hospitalization avoided. Remdesivir gained some fame because it was used to treat Donald Trump, then President of the United States, in October 2020.
Monoclonal antibodies are drugs that are the subject of an intense campaign by the Canadian Community Health Association, an organization founded by Montreal businessman Samuel Herzog. In the United States, monoclonal antibodies, which must be given by transfusion in the first days after the onset of symptoms, are in some states administered by paramedics dispatched to the homes of patients at risk. In Canada, they are usually administered in the hospital, which increases logistical problems. Monoclonal antibody transfusion pilot projects in outpatient departments (commonly referred to as outpatient clinics) have been initiated in Ontario.
Preliminary data, however, suggests that some monoclonal antibodies are less effective against the Omicron variant, according to Dr.r Lee. A South African study published on January 26 in the New England Journal of Medicine confirms this, but finds that molnupiravir and remdesivir retain their effectiveness against Omicron. The South African study, however, did not test Paxlovid.
Note that since clinical trials on fluvoxamine have not yet been completed, this treatment does not appear to be widely used in Canada and the United States. “We saw in the United States, at the start of the pandemic, a big increase in the prescription of certain drugs which ultimately do nothing against COVID-19, such as hydroxychloroquine or ivermectin, indicates the Dr Lee. But we did not see the same phenomenon with colchicine or fluvoxamine. This is perhaps an illustration of the proverb “scalded cat fears cold water”. »