(CBS) = Get your flu vaccine. That's the main advice from health experts as the flu season ramps up.
But just how effective is the flu shot, and is the nasal flu spray just as good?
Health officials say getting vaccinated is the best way to protect against the flu, but it's not always a guarantee.
A new study shows all vaccines aren't created equal.
When it comes to protecting adults, researchers found the traditional shot to be much more effective than nasal flu spray .
They looked at about 2000 healthy adults in the 2007-2008 season and found that flu injections were 68-percent effective in preventing flu, while the nasal vaccine FluMist was 36-percent effective.
One reason the nasal spray may not work as well in adults is because it's made with a live weakened virus that many may have already come in contact with.
Typically, the flu shot is between 70 and 80 percent effective in younger adults. How well it works varies every year because scientists make the vaccine before flu season and can't always predict which viruses will be circulating.
Health experts still stress vaccination is a must.
Dr. Arnold Monto of the University of Michigan School of Public Health says it's the best thing we have to prevent flu.
The FluMist nasal spray vaccine is approved for people ages 2-49 years old. It's not recommended for pregnant women or those with chronic health conditions.