Nurse Laura Gill injects the a flu vaccine into a patient at a vaccination clinic in Ottawa in 2009. A report released today suggests the current vaccines offer moderate protection some years and less in others. (Pawel Dwulit/Canadian Press)

A new report says flu vaccine is not as effective as public health messaging suggests, and new and better vaccines are needed.

The report suggests the current vaccines offer moderate protection some years and less in others.

The authors said the problem is that having vaccine that is deemed good enough is a disincentive for the industry to develop longer-lasting and more effective flu shots — especially given that better vaccines would likely cost significantly more.

The report, titled Comprehensive Influenza Vaccine Initiative, was written by public health experts at the Center for Infectious Diseases Research and Policy at the University of Minnesota.

The authors strongly advocate for major investments to develop new flu vaccines but say in the meantime, people should continue to use the currently available shots.

It questions many of the dogmas that are accepted about flu vaccine, including that vaccinating children will protect the elderly, who don't mount a good immune response to flu vaccine.

As well, it says there is no evidence to support the idea that flu vaccine is more effective in years when the strains included in the shot are a good match for those circulating in nature.

The 160-page report is the result of a three-year investigation into the science supporting flu vaccine efficacy and safety and the decision-making processes that led to the U.S. policy to recommend all Americans get a flu shot every year.

The work was done with a grant from the Alfred P. Sloan Foundation.