The vaccine's effectiveness can also vary depending on the characteristics of the person being vaccinated (such as their age and health), and the similarity or "match" between the flu strains included in the vaccine and the flu viruses spreading in the community.
Adults with chronic conditions need the flu vaccine because people with respiratory diseases like COPD, emphysema or asthma are seven times more likely to die if they catch flu, and people with cardiovascular problems like chronic heart disease or angina, or have had a stroke, are 11 times more likely to die.
Vaccine skeptics may say they have a point after Nova Scotia's last flu season. Women are also more likely to be vaccinated than men, and they tend to seek health care more quickly when they are sick.
Myth #2 - The flu shot can give you the flu.
It's still early in flu season, but the CDC is already warning people this could be another particularly nasty one. Surface proteins on the virus particles are shown in black.
Fact #6 - The flu changes every year. It takes about two weeks after vaccination for antibodies that protect against flu to develop in the body, so make plans to get vaccinated early in fall, before flu season begins. The overall vaccine effectiveness for women was considerably higher (49% versus only 38% for men). "The virus any one year may be wearing one coat or wearing a different coat, and the vaccine manufactures and public health world tries to predict what coat that virus will be wearing".
The main strains that circulated last winter were Flu A (H3N2), which largely affects older people, and Flu B.
"The authors wrote that "...these findings suggest that biological gender differences in response to the vaccine, rather than gender differences in health care seeking or vaccination status reporting, likely explains the observed differences in influenza VE between males and females".
"I encourage anyone who is eligible to take up the offer of their free vaccine; it is there to protect you and the rest of your family from a potentially very serious illness". The vaccine is offered through local Global Positioning System and pharmacies.
"It's key that everyone understands our best protection is a seasonal flu vaccine, which are now available and can help mitigate the severity of this season", said Dr. Andi Shane, medical director of hospital epidemiology at Children's Healthcare of Atlanta.
Jill Baber is influenza surveillance coordinator with the health department.
Flu is a viral infection that is spread through coughs and sneezes.