The Canadian government quietly gave the green light for doctors to prescribe a drug that can prevent the transmission of HIV last week. The next step will be making the revolutionary drug affordable.

Truvada, as one of the drugs that make up the antiretroviral drug cocktail, is one of the most effective drugs prescribed to manage HIV. But, in recent years, clinical trials have shown that the drug is remarkably effective in actually stopping the virus altogether.

By taking one tablet a day, patients could virtually eliminate their chance of contracting the virus, with the most recent studies showing that — if taken correctly — the treatment could reduce the risk of transmission by as much as 99 per cent.

The treatment is generally referred to as pre-exposure prophylaxis (PrEP). A spokesperson for Health Canada confirmed to VICE News on Monday that Truvada has been approved to do exactly that.

Canada, thanks in part to the drug company that manufactures the drug, is late to the game.

The American Food and Drug Administration came out of the gate in 2012, approving the drug for use to prevent HIV transmission. Two years later, the World Health Organization released a policy saying it "strongly recommends" that men who have sex with men take the drug regularly, eventually releasing a new policy that recommends PrEP for a number of high-risk groups.

But the treatment didn't make it to Canada. Gilead Sciences, the drug manufacturer, only applied for approval for Truvada in 2015, with Health Canada only confirming the application in December, saying it could take nearly a year to decide on the drug.

While the bureaucracy considered the drug, some doctors began prescribing the drug to HIV negative patients anyway — a practise referred to as an "off-label prescription." That decision, however, was at the discretion of the doctor.

The most recent announcement, first noticed by LGBTQ news site DailyXtra, is a big shift.

"This has been a very exciting and important development," said Sean Hosein, Science and Medicine Editor for the Canadian AIDS Treatment Information Exchange (CATIE). He said guidelines from specialists on PrEP will be coming in the near future, and that "now it's in the provinces and territories' ballparks."

Some provinces already recognize the drug's use for preventing transmission of HIV, but Hosein said now that the drug has Ottawa's approval, the regional governments need to figure out how to deploy the drug.

"The ball is rolling, but it needs to roll a little faster."

There is definitely a demand for PrEP. In Canada, HIV transmission rates have remained largely steady over 20 years, with an average of 2,300 new cases being reported each year. While half of the 70,000 HIV-positive people living in Canada are either gay or men who have sex with men, the virus has disproportionately hit the country's indigenous population, with a quarter of reported cases coming from Aboriginal peoples.

The drug, in many ways, is touted as a silver bullet. Serious side effects are rare, while more common ones — headaches and nausea — are minor.

But there are still drawbacks.

"Truvada is very good at reducing risk," said Hosein. "But it costs money."

For one, the pills are prohibitively expensive, with a month-long prescription costing as much as $1,000 CAD. Given that the drug, until last week, was not officially recognized as a preventative treatment, it was unclear which insurance plans covered and did not cover the drug. Now that it has received official approval from the federal government, it is expected that more insurance plans will cover part of the cost.

"To facilitate access, private insurance companies need to move swiftly to add Truvada (when used as PrEP) to their list of reimbursed medicines," reads a statement from CATIE, lauding the drug's approval. "However, not everyone at high risk for HIV has private insurance. Canada's provinces and territories now need to consider adding PrEP to their lists of subsidized medicines."

The statement from CATIE said without the government subsidies, "it is unlikely that Truvada will reach its full potential to significantly stem the spread of HIV."

Hosein said he's happy, as "the ball is rolling, but it needs to roll a little faster."

But not everybody is as optimistic about PrEP. Michael Weinstein, the president of the Los Angeles-based AIDS Healthcare Foundation told the New York Times that the treatment was "a public health disaster in the making" and called Truvada a "party drug."

While opponents to the drug like Weinstein are in a small minority in the HIV/AIDS community, his comments reflect a concern in the gay community that HIV-negative men who are on PrEP will use the drug as an excuse to have unprotected sex, and increase the spread of other sexually-transmitted infections.

The Canadian government is stressing that Truvada is supposed to improve other prevention measures, not replace them.

"The drug is intended for use by high risk individuals — such as those whose sexual partner is HIV positive — in combination with safer sex practises, including condom use," a spokesperson for Health Canada told VICE News in an email.

HIV testing is also supposed to be required before the drug is prescribed, underlining a fear that the drug could, if prescribed to a person who is unaware that they are HIV-positive, develop more drug-resistant strains of HIV.