Ivermectin is a Nobel Prize-winning anti-parasitic drug that has improved the health of millions and has helped to eradicate diseases like river blindness in multiple countries.
But there's a shortage of the drug in Canada, as global demand surges due to unproven claims that the medicine can be used to treat COVID-19.
That shortage could put people who actually need it for treatment at risk, including those who are more susceptible to illness from parasites due to COVID-19.
"The use of this medication for COVID is really putting people who are already in a difficult situation in an even worse situation," said Barry Power of the Canadian Pharmacists Association. "I would really urge people to think twice before trying to access this medication that has been proven to do nothing in the case of COVID."
Quantities of the drug have been limited in Canada since January due to global demand, and the shortage is expected to continue until the end of this year.
On Tuesday, Health Canada issued an advisory asking people not to take the drug to treat COVID-19 after reports that some people were taking the veterinary form of the medicine intended for livestock.
"There is no evidence that ivermectin in either [the human or veterinary] formulation is safe or effective when used for those purposes," the federal agency warned.
'People were trying everything'
Demand for ivermectin started to rise in December last year.
Early, limited and lower-quality studies suggested the drug might show promise as an anti-viral as well as an anti-parasitic — with hope that further study could prove it inhibits the growth of the novel coronavirus in human cells and improve patient's outcomes.
People who do need ivermectin may be in a tough spot because there simply may not be the supply that we need to have. -Barry Power, Canadian Pharmacists Association
Dr. Lynora Saxinger, an infectious disease specialist at the University of Alberta, explained that those early studies did not consist of high-quality data.
That's either because in initial positive reports patients were receiving multiple medications, so the effect of ivermectin couldn't be parsed out, or because high doses that showed promise in test tubes didn't translate to human subjects.
That didn't stop the drug from being used widely in an attempt to treat patients in some countries like Colombia, because it was easily available and inexpensive, Saxinger said.
If you're a doctor faced with a hospital full of patients sick with a new virus, it makes sense to get creative.
"In the beginning [of the pandemic] people were trying everything in a sense of, I think, desperation," she said.
"Really, the only way to tell if something is truly helping is to do a randomized controlled trial … the higher-quality trials, by and large, have not shown any benefit whatsoever."
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Those early studies and the drug's speculative use have fuelled misinformation campaigns online — primarily from right-wing politicians and media personalities promoting the drug's use.
Merck, the manufacturer of ivermectin, confirmed its scientists have found no scientific basis for ivermectin's efficacy against COVID-19, also citing a concerning lack of safety data in most studies.
The company has donated more than four billion ivermectin doses globally to treat river blindness, an illness caused by larvae left in the body from blackfly bites, ending transmission in four countries in Latin America and five regions in Africa.
While river blindness primarily affects people in those regions, there is another illness treated by ivermectin that could put many immigrants to Canada as well as those who live in countries with limited access to COVID-19 vaccines at risk.
Strongyloides stercoralis is an intestinal roundworm that is estimated to affect somewhere between nine and 77 per cent of immigrants and refugees in Canada, according to one study from the Canadian Medical Association Journal. Health Canada says as many as 2.5 million people could have it.
The reason that number ranges so widely is because most people infected can carry the roundworm for decades after spending time in a tropical climate — without knowing they have it.
Health Canada warns that patients with severe cases of COVID-19, who need to be treated with steroids, could see their immune systems suppressed. That would potentially put them at risk of severe outcomes or even death from a parasite they don't even know they have.
"For example, if we had someone who's born in another country where they have a lot of strongyloides and we're going to put them on high-dose steroids, which is pretty much the situation with COVID … we would consider treating them [with ivermectin] just to eliminate that risk," Saxinger said.
Power said there are other medications that can be used to treat parasites but in some cases ivermectin might be the only option.
"People who do need ivermectin may be in a tough spot because there simply may not be the supply that we need to have for the people who will need it for the treatment of parasites," Power said. "It is concerning for those people."
Drug shortage 'may compound' barriers to care
Dr. Bukola Salami is an associate professor of nursing at the University of Alberta who researches policies that shape health outcomes for immigrants and racialized people.
She said immigrants already face barriers to accessing medical treatment and that newcomers have been harder hit by the pandemic.
Salami said a drug shortage, "may compound some of the barriers that already exist … language, immigration status can be a barrier to accessing health services. So it does give me concern."
Health Canada said it's closely monitoring all potential treatments for COVID-19, including ivermectin — even though no clinical trial applications have been submitted for the drug in this country.
Saxinger said it seems contradictory that some are so desperate to access an unproven drug like ivermectin that they're turning to veterinary forms of the medication, while uptake of the thoroughly studied, Health Canada-approved COVID-19 vaccines has stalled in some regions like Alberta.
"I think the difference might be the way the human brain works with anecdotes and narratives versus data. I think that testimonials … can carry a lot more weight," she said.
"We do have things that we can do for COVID that are evidence supported," like vaccination, Saxinger said. "But if people are holding out for unproven therapies, we might actually be missing opportunities to offer them proven therapies."