Canada has been hit earlier and harder by the flu this season, resulting in a shortage of Tamiflu, but an infectious disease specialist says the release of the national stockpile of the antiviral medication should dramatically reduce the threat to Canadians’ health.

On Tuesday, the Public Health Agency of Canada and Health Canada announced plans to immediately release a supply of the drug from the country's National Emergency Stockpile System.

The antiviral drug is typically used to treat early cases of influenza, particularly in those who are at high risk of complications, such as the elderly, young children and pregnant women.

Dr. Neil Rau said this season the flu outbreak has been much more aggressive than in past years. As a result, local physicians have simply run out of Tamiflu.

"We're getting stories of a lot of community illness, emergency rooms being overrun by people who are sick, some hospitals even having to think about what to do because they have so many patients coming in, and they're wondering are they going to have to find more staff or ICU beds," Rau said.

However, he added that on a local level the flu peak usually only lasts a few weeks before cases start to drop off and the threat subsides.

"So we're not going to have this problem going on for all of the winter and I think there's such a large stockpile available that we're going to overcome this problem pretty quickly," Rau said.

The Tamiflu shortage comes as Canada sees one of its earliest spikes in flu cases in years. This year's flu is also causing more severe illness than other strains seen in the last two years.

In a statement, Tamiflu manufacturer Roche Canada said the "unexpectedly severe" flu season has led to "greater than normal demand" for the drug.

The company said it ordered additional units of the antiviral medication as soon as early reports showed an increase in flu cases last month. It said it is "actively working to address the needs of priority patient populations, specifically hospitals and nursing homes with a confirmed outbreak."

Tamiflu, known also by its drug name oseltamivir, is an antiviral medication used for the early treatment of influenza -- particularly in those at high risk of flu complications, such as the elderly, young children, individuals with other medical conditions or pregnant women.

It should not be confused with the seasonal flu vaccine, which Health Canada says remains the best protection against the flu virus.

PHAC reminds Canadians that it's not too late to get the flu shot and that this year's vaccine matches the circulating influenza strains very well.