The Anti-COVID Arsenal

"I haven't seen evidence of even a submission to Health Canada."

"They've been burned twice now with purchasing large amounts and not able to utilize much of it."

"[Monoclonal antibodies bind to the spike protein. It's like a glove fitting on a hand.] The problem is the hand keeps changing. It needs to be a good fit."

"It's hard to know exactly how much [more a larger dose of the drug is able to neutralize BA.2, the offshoot of Omicron], but it's somewhere between 30 to 45 times less able to neutralize than normally."

Dr.Andrew Morris, infectious diseases co-chair of Ontario's drugs and biologies clinical practice guidelines working group

Monoclonal antibody therapy -- which is to say laboratory-produced molecules that attach to the spike protein of the SARS-CoV2 virus which it uses to invade human cells -- can help to reduce the risk of COVID progressing from mild to severe. Given to those people at  high risk of being hospitalized or dying of COVID, reflective of their age or medical conditions. The treatment with sotrovimab is costly at $2,100 for each course of treatment, recognized as the sole available monoclonal antibody treatment in Canada effective against BA.1, Omicron.

GSK HQ U.K. Photo Hannah McKay / REUTERS

Sotrovimab proved more effective than two other antibody treatments. Laboratory experiments, however, revealed a dramatic drop in the drug's capacity of effectiveness against Omicron's successor. The journal Nature reported that researchers are struggling to keep pace with SARS-CoV-2 as the virus evolves. "With monoclonal antibodies, we're trying to hit a moving target", explained  David Ho, virologist at Columbia University, to the journal.

The Omicron subvariant, now nudging aside Delta, in its spread across the United States and Canada, now representing about 50 percent of all new cases, has shown itself to be resistant against the monoclonal therapy. The drug appears capable of causing treatment-resistant mutations in a small number of people, according to Australian researchers. "For those two reasons, it does not make sense to give it to patients when BA.2 has become the dominant strain through most of Canada", commented Dr. Morris.

Use of the drug across New York, New Jersey and eight other states or territories in the United States where BA.2 accounts for over 50 percent of confirmed COVID-19 infections has seen the U.S. Food and Drug Administration pause use of the drug. Its manufacturer in response, is preparing to submit data supporting use of a higher dose to achieve a higher rate of effectiveness against Omicron BA.2.

"[Once the drug's manufacturer GSK shares its data with global health regulators] the department will communicate the information on our web portal as well as with health-care professionals."

"Health-care professionals are responsible for making decisions with regard to the best treatment options for their patients considering the local epidemiological context."

Health Canada

Evolutionary changes with SARS-CoV-2 have turned out to be much more unpredictable and swift in their turnout than researchers had anticipated. There is one monoclonal antibody therapy available in the U.S. that appears to be effective againts BA.2. But the critical fact is that each time the protein undergoes alteration or hyper-mutates, there is the potential to render the monoclonals inactive.

"We don't yet know whether this will result in clinical failure. It certainly raises the question."

"But that's a big step away from being able to say, unquestionably, that sotrovimab has no effect."

"[However, if you ask me based on the available data we have, I think it's a very good thing to be questioning whether we should at least pause on this."

"[With increasing supplies of Paxlovid, Pfizer's oral anti-COVID pill], we have at least something we can reliably turn to."

Dr.Matthew Oughton, infectious diseases specialist, Montreal Jewish General Hospital