Goudreau says "the relatively low percentage of effectiveness in Australia is due to many factors, including the shifting and changing of the flu virus each season".
Flu activity is listed as widespread in four states: Massachusetts, Georgia, Louisiana and Oklahoma.
However, 6 percent of the cases with serious flu complications reported in the previous flu season involved people with chronic liver disease, so those people should also be aware of the increased risk, Lo said.
While this year's vaccine works well against numerous flu virus strains out there, recent studies indicate the vaccine is less effective against the H3N2 strain.
This season, the CDC advises that only injectable flu vaccines (flu shots) are recommended.
Pregnant women, children aged between six to 59 months, the elderly, individuals with specific chronic medical conditions such as HIV/AIDS, asthma, and chronic heart or lung diseases, and health-care workers have the highest risk of contracting the virus, according to WHO.
"Human immune defenses become weaker with age, which places older people at greater risk of severe illness", explained Dr. Levine.
This winter all visitors to Vancouver hospitals and nursing homes once again must get a flu shot or wear a surgical mask.
People taking medication for hepatitis C or undergoing interferon therapy should not worry that the flu vaccine will affect their treatment, Lee said, adding that they should get vaccinated as soon as possible for protection against the flu.
Doctors still want you to get the shot, though.
The New England Journal of Medicine says this year's shot is only about 10% effective against the strain that hit Australia the hardest, which is the one we're expecting to get.