This year’s flu vaccine might only be 10% effective against predominant strain

Click to play video: 'Ask An Expert: Flu shots'
Ask An Expert: Flu shots
Ask An Expert: Flu shots – Nov 5, 2017

Doctors are warning that this flu season could be a bad one.

They say a powerful strain that’s caused severe illnesses in Australia is also expected to cause problems in North America — and one study says this year’s flu vaccine is only 10 per cent effective against the main strain.

READ MORE: Here’s why Canada may be in for a miserable 2017-18 flu season 

A study published in the New England Journal of Medicine at the end of November explained that in Australia’s flu season, Influenza A (H3N2) viruses were predominant.

The vaccine used in the Southern Hemisphere has the same composition of the one used in North America.

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WATCH: A new study shows the flu vaccine could only be 10 per cent effective in fighting this year’s main strain of the virus. The data focuses on the Southern Hemisphere, and as Lauren Pullen reports, it may be too soon to say it’s the same case here.

Click to play video: 'Flu shot could be only 10% effective against predominant strain'
Flu shot could be only 10% effective against predominant strain

“The cornerstone of influenza prevention and epidemic control is strain-specific vaccination,” the publication explained. “Since influenza viruses are subject to continual antigenic changes (‘antigenic drift’), vaccine updates are recommended by the World Health Organization each February for the Northern Hemisphere and each September for the Southern Hemisphere.

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READ MORE: Flu vaccine offered little or no protection in Canada this year

“This guidance relies on global viral surveillance data from the previous five to eight months and occurs six to nine months before vaccine deployment.

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“In addition, there are always several closely related strains circulating; therefore, experts must combine antigenic and genetic characterization and modelling to predict which strains are likely to predominate in the coming season.”

READ MORE: What happens to your body when you get the flu, step by step

The study explains “vaccine mismatches” occur when circulating influenza strains change after the decision about vaccine composition is made, which can lead to reduced effectiveness. It goes on to say that even when vaccines are well-matched to current viruses, vaccine effectiveness ranges between 40 to 60 per cent.

The study points out seasonal flu causes between 300,000 and 500,000 deaths globally each year, according to the World Health Organization (WHO).

The publication suggests the development of a “universal” influenza vaccine that will “protect against seasonal influenza drift variants.”

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Despite the varying degrees of effectiveness, the authors stress current flu vaccines “remain a valuable public health tool” and suggest “it is always better to get vaccinated than not to get vaccinated.”

READ MORE: Edmonton sees 1st influenza-related death of the season 

That stance was echoed by Alberta’s health minister when she was asked about vaccination rates and effectiveness on Monday.

“We’re vaccinating for more strains than we have in the past,” Sarah Hoffman said. “We know the best way to protect yourself is to get immunized. I want to continue urging everyone to do so.

“We know that this is deadly flu — it is every year,” she added. “The best way to protect yourself, but also to protect those who are in our community who are immunosuppressed and can’t get vaccinated — those who are going through chemotherapy treatments, for example — is to make sure the vast majority of us immunized.

For more information on immunization clinics and schedules, click here.

READ MORE: 7 steps to surviving the cold and flu season without getting sick

Hoffman said Alberta will release more flu numbers soon, but said it’s still quite early to make conclusions about vaccine effectiveness.

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“But I can tell you getting the immunization is more effective than not getting the immunization. We’re hopeful that this is the right mix of strains for us to all have better outcomes.”

READ MORE: A first for flu season: a new, more robust four-strain vaccine 

Officials continue to offer the standard health reminders: wash your hands frequently, keep away from people who may be sick, and if you’re sick, stay home from work.

— With files from The Canadian Press

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