A Promising New Way to Prevent HIV Infections

A British Columbia-led research group is paving the way for a landmark preventative HIV medication it hopes can reduce Canada’s stagnant rates of new HIV infections.

Long-acting pre-exposure prophylaxis, or PrEP, is more than 99 per cent effective at preventing the development of HIV when it is injected every two months, according to clinical trial data reported by manufacturer ViiV Healthcare.

The injectable drug, cabotegravir, was approved by the U.S. Food and Drug Administration last December but has not yet been submitted to Health Canada for approval.

Currently, the injectable medication is approved to treat HIV among the nearly 63,000 Canadians estimated to live with the virus, but not to be used preventatively.

And while an oral form of PrEP has been available in Canada since 2016 and the United States since 2012, experts say increasing treatment options will be key to reducing the more than 1,500 estimated new infections in Canada each year.

“Where we are today is obviously a much better place than we've ever been,” said Michael Montess, a postdoctoral associate at Western University.

“But if you want to actually have those HIV numbers decrease, we're going to want to find more innovative strategies and figure out how to make sure that they're being as effective as possible.”

Long-acting injectable PrEP is lower-maintenance and improves adherence, the single most significant factor in the medication’s success at preventing HIV. Similar long-acting shots have been developed for contraceptive and psychiatric medications.

“Once you have that [PrEP] shot, you can know that you are almost 100 per cent covered for the next two months,” said Montess. “So you don’t have to worry about forgetting a pill or anticipating a possible exposure and timing it correctly. The shot really gives you a lot of flexibility and keeps adherence high.”

Montess, a former postdoc at the University of Victoria, is working with colleagues in British Columbia and Ontario to identify and reduce barriers to long-acting injectable PrEP before it becomes available.

The Future of PrEP is Now project, funded by the Canadian Institutes of Health Research, will also investigate challenges with oral PrEP to make both versions more easily accessible.

The same medication used for PrEP was first used to treat HIV, which is transmitted through blood, semen, rectal and vaginal fluids during sex and needle-sharing, and through breastmilk from parent to child.

The drug is antiretroviral and prevents HIV from multiplying enough to be transmitted or quickly advance illness in more than 95 per cent of people who take it, according to the Public Health Agency of Canada.

It is one of several milestone treatments developed since 1996 that mean being HIV-positive is no longer a certain sentence to dying of AIDS. AIDS has killed more than 40 million people worldwide and first began to infect Two-Spirit people and men who have sex with men in Canada and the United States in the early 1980s.

If someone is exposed while already on PrEP, Montess explained, the medication prevents the virus from taking hold or multiplying at all in more than 99 per cent of cases.

And prevention is key because about 13 per cent of cases in Canada are still undiagnosed and stigma around the disease and who it can affect continues to prevent people from getting tested.

“The more options that are available, the more it's going to fit different people's schedules and lifestyles,” said Montess, “so more people are going to be able to actually access it, use it effectively, and then stop the negative health outcomes that they are interested in stopping.”

HIV has disproportionately impacted gay, bisexual and trans men and Two-Spirit people who have sex with men since the AIDS epidemic began.

Advocacy and community care by the queer and trans community has been instrumental to Canada and British Columbia’s relatively successful HIV prevention and treatment plans, Montess said.

But HIV can infect anyone. Substance use, having multiple sexual partners and having sex without using a physical barrier like a condom or dental dam are key risk factors.

The working group is partnering with the Community-Based Research Centre in Vancouver to study how to make long-acting injectable PrEP more available to people living in rural and remote areas, as well as to people who are Indigenous, Black, racialized, trans, non-binary, Two-Spirit or using substances when it arrives.

Trust in health care is low among these demographics due to historical and ongoing medical racism and neglect, Montess added, and many people do not wish to access health care more than they need to.

The project aims to engage these groups and look at how health-care providers, whether at sexual health clinics, pharmacies, family doctor offices or street outreach teams, can reduce barriers to providing PrEP.

PrEP is free for people in B.C. who are enrolled in MSP, but people elsewhere or who are uninsured may have to pay the $250 average monthly cost out of pocket.

Some people may also move or travel and need an easy way to arrange their next shot in a new location, Montess said, and some may not have a doctor who is familiar or comfortable with prescribing PrEP due to ignorance or stigma.

While long-acting PrEP has not yet been submitted for approval in Canada, Montess says it is important to improve existing treatments and ensure new ones are as effective as possible.

“We’re really trying to anticipate its eventual arrival in Canada so that we can hit the ground running,” he said, “and make sure that we're learning specifically from our experience with oral PrEP to pre-empt certain challenges when it comes to uptake and adherence.”