The country’s federal drug regulator issued a notice to health-care professionals on Thursday, indicating that sotrovimab will not likely work against BA.2, the dominant strain of Omicron across the globe.
Health Canada did mention the treatment continues to be effective against the Omicron BA.1 and BA.1.1 sub-variants.
“Local epidemiology and individual exposure to variants should be taken into consideration before use of sotrovimab,” Health Canada said.
“Use of sotrovimab 500 mg IV should be limited to when the patient is likely to have been infected with a variant that is susceptible to the authorized dose.”
The sotrovimab drug by GlaxoSmithKline was approved for use by Health Canada in July and is only given to COVID-19 patients at high risk of severe illness leading to hospitalization, or dying because of age or medical conditions. It is administered intravenously.
Sotrovimab, along with Eli Lilly’s bamlanivimab and Regeneron’s antibody cocktail of casirivimab and imdevimab, is among three monoclonal antibodies that have been used in Canada since the start of the pandemic.
Like other monoclonal antibodies, sotrovimab is a direct shot of antibodies targeting the virus that causes COVID-19.
It is designed to block the virus from attaching to and entering human cells, which can help people who have already been infected better fight the virus, lessening the chance of severe illness and hospitalization.
It was proving to be in high demand once Omicron emerged, given the variant was neutralizing the effect of other monoclonal antibody treatments.
However, BA.2 seems to have reduced the effectiveness of sotrovimab. Alberta on Wednesday suspended its use citing its ineffectiveness against the sub-variant.
Health Canada isn’t the only regulator warning of the apparent decline in performance.
Earlier this month, the U.S. Food and Drug Administration said the drug should no longer be used because it is likely ineffective against BA.2.
Sotrovimab is no longer authorized to treat patients in any U.S. state or territory. The decision was expected because the FDA had repeatedly restricted the drug’s use in the northeast and other regions as the BA.2 version of Omicron became dominant.
— with files from Saba Aziz and The Associated Press