CANMORE, ALTA. -- The emergence of the highly transmissible Omicron variant has driven a fifth and record-breaking wave of COVID-19 in Canada, prompting further discussions around vaccine efficacy, boosters, and therapeutic treatments for those who fall ill.
Several different types of therapies for COVID-19 have been approved for use in Canada, including a number of treatments that are being experimented with as part of clinical trials across the country.
Here are some of the treatments that are available in Canada.
REMDESIVIR
In July 2020, Health Canada authorized the use of remdesivir, an antiviral medication originally used to help treat Ebola, to treat COVID-19 patients with severe symptoms such as pneumonia, or those who require extra oxygen to breathe.
It was the first drug authorized to treat COVID-19 in Canada.
, remdesivir is recommended for use in Canadians aged 12 years and older who weigh at least 40 kilograms. The treatment is to be administered through an IV and be used only in health-care facilities where patients can be closely monitored.
"This is a medication that works to inhibit the virus itself; many of the other therapeutics we've seen used or attempted for use in the treatment of COVID-related disease have been around the immune system," infectious disease expert Dr. Lisa Barrett of Dalhousie University in Halifax explained to Â鶹´«Ã½ Channel at the time.
"However, this one is designed to directly inhibit the virus itself, and has been used or tested for use in other viral infections previously."
In November 2020, the World Health Organization (WHO) updated its ongoing guidance on COVID-19 medications to advise against the use of remdesivir, citing a lack of evidence to suggest that the drug affects the risk of dying from COVID -19 or needing mechanical ventilation. However, this did not affect Health Canada’s decision to authorize the use of the drug.
Some of the latest research into remdesivir, published in April 2021, suggest that it appears to be as safe and effective for use in children with COVID-19 as in adults, with a low incidence of serious adverse events.
BAMLANIVIMAB
Approved for use by Health Canada in November 2020, bamlanivimab was the first for use in treating COVID-19.
The drug mimics the immune system's ability to fight off the virus and was developed by AbCellera Biologics Inc. in Vancouver with the support of the federal government.
It is recommended for treating adults and children aged 12 and older who weigh at least 40 kg. It’s used to treat those who are at high risk of progressing to severe COVID-19 complications or hospitalization, but not those with severe respiratory disease.
However, in April 2021, Health Canada issued a warning about the "potential risk of treatment failure" for the Canadian-made drug, saying it may not protect against infection from some variants.
According to Health Canada, bamlanivimab "exhibited reduced activity against SARS-CoV-2 variants" with the E484K and L452R mutations. This includes the B.1.351 variant first identified in South Africa, the P.1 variant first found in Brazil, the B.1.427/B.1.429 variant reported in California, and the B.1.526 variant first identified in New York.
While countries around the world have been using the drug, almost none of Canada's 26,000 doses have been used. Doctors say this is because a plan on how to administer the drug was never made due to the fact that it must be administered intravenously within the first 10 days of infection.
CASIRIVIMAB AND IMDEVIMAB
In June 2021, Health Canada authorized the use of to be administered together as a monoclonal antibody therapy. Similar to bamlanivimab, the drugs are used to treat mild to moderate COVID-19 in adults and children aged 12 and older who are at high risk for hospitalization or COVID-related complications.
The WHO has backed the use of the antibodies in select high-risk patients and they are used widely in the U.S. to treat COVID-19. But the use in Canada has been spotty.
Quebec received a of the monoclonal antibody cocktail in October.
Doctors in Hamilton, Ont. are also piloting the province’s for outpatients using casirivimab and imdevimab, referencing data that shows the therapy reduced hospitalization by 71 per cent and death by seven per cent in high-risk COVID-positive patients.
SOTROVIMAB
Another monoclonal antibody treatment, sotrovimab, was approved for use in Canada in July 2021. The injectable drug is used to treat mild to moderate COVID-19 in adults and children aged 12 and older who are at high risk for hospitalization or COVID-related complications.
On Wednesday, health officials in Alberta revealed they have been administering sotrovimab to COVID-19 patients aged 65 and older who are unvaccinated.
“The treatment is being rolled out across the province in a phased approach, starting with those with the highest risk of severe outcomes, like hospitalization,†the province’s chief medical officer of health Dr. Deena Hinshaw said .
“Let me stress that sotrovimab is not a replacement for COVID-19 vaccines… as vaccines are the most effective method to prevent serious outcomes from the disease.â€
This comes amid news that lab tests and a study on hamsters suggest the sotrovimab antibody cocktail works against viruses that were bio-engineered to carry a number of hallmark mutations of the newly discovered Omicron variant.
PAXLOVID
Health Canada authorized the use of Paxlovid, a two-tablet antiviral oral medication made by Pfizer, in January 2022. The treatment is the first oral and at-home prescription medication cleared for use in Canada and is aimed at treating mild to moderate cases of COVID-19 in adults aged 18 and older after they have had a confirmed positive test and are at high risk of becoming seriously ill.
The health agency said Paxlovid cannot be used to prevent infections or to treat those who are already hospitalized with a severe case and it cannot be given to those under 18. It was also not authorized for use for longer than five consecutive days.
One tablet is nirmatrelvir, which blocks a key enzyme critical to the virus’ replication cycle, and the other tablet is ritonavir, an existing drug that has been used in combination with other antiviral medications and serves to enhance the efficacy of nirmatrelvir.
The drug maker said that in a randomized, double-blind study of more than 380 patients, there was an 89 per cent reduction in the risk of being hospitalized or dying of COVID-19 in patients that received Pfizer’s pill, compared to the study group that received a placebo. Severe, adverse reactions may be possible, however, if the drug is taken along with certain other medications, .
PENDING TREATMENTS
MOLNUPIRAVIR
Health Canada says it is still reviewing data regarding an experimental pill from drug maker Merck, which the company says can reduce hospitalizations and deaths by half in patients sick with COVID-19.
Merck Canada said in December 2021 that it was partnering with Thermo Fisher Scientific to manufacture the drug in Canada for global distribution.
Molnupiravir, a twice-daily oral antiviral agent taken within five days after the onset of symptoms, has shown modest benefits and potential safety issues in trials. Most experts backing the treatment stress that it shouldn’t be used by anyone who is pregnant and suggest extra precautions before the drug is prescribed, such as pregnancy tests for women of child-bearing age.
The drug targets an enzyme the coronavirus uses to reproduce itself, inserting errors into its genetic code that slow its ability to spread and take over human cells – leading some independent experts to question whether the drug could potentially cause mutations leading to birth defects or tumours.
The drug has not been tested in those who are vaccinated.
On Nov. 30, the U.S. Food and Drug Administration backed the use of the drug in adults with mild-to-moderate COVID-19 who face greater risk of complications, including older people and those with conditions like obesity and asthma. The U.K. has also authorized its use.
Health Canada has offered no timeline for completion of the review process.
- With files from Alexandra Mae Jones, Brooklyn Neustaeter, Solarina Ho, Rachel Aiello, The Canadian Press and The Associated Press
