MADISON (WMSN) -- The seasonal flu vaccine isn't as effective as the medical community once thought, according to a new study headed by the University of Minnesota.

An analysis of 5,707 medical articles published between 1967 and 2011 found the seasonal flu vaccine was 59 percent effective against influenza in healthy adults. Previous studies have placed the effectiveness of the vaccine at 70 to 90 percent.

I think all these data are pointing out that there surely can be benefit from the vaccine by different age groups, but that it's more limited than we had often led the public to believe," said lead author Dr. Michael Osterholm of the University of Minnesota.

Researchers say that while people should still get a yearly vaccination, the industry is badly in need of an upgrade.

The flu vaccine has been on the market since 1967. The active protein in the shot has been around since the 1940s.

"When you have a vaccine that is said by public health and the medical community effective,
it's universally recommended, it's cheap, and it's safe, that's a huge barrier of entry for anyone
trying to bring in a new vaccine into the market," said Osterholm.