A vaccine that switches on immune cells in the nose could be the key to preventing flu-related pneumonia, Australian scientists say.

It might be possible to stop the flu from spreading to the lungs and causing a serious infection by targeting the common virus in the nose.

Researchers at the University of Melbourne's Doherty Institute for Infection and Immunity have, for the first time, discovered the nasal passage is home to virus-fighting white blood cells that when switched on can block inhaled influenza particles from spreading.

Essentially, they have discovered how to stop influenza "at the gates".

Professor Linda Wakim says immunising the upper respiratory tract with a nasal spray could be key to preventing many cases of pneumonia in Australia.

It could also mean that down the track that the annual flu jab could become a thing of the past.

Pneumonia is among the top 15 contributing causes of death nationally and among the top five leading causes of hospitalisation in Australia.

The influenza virus is a leading cause of the very serious lung infection.

Previous influenza research has focused on these flu-fighting T cells, central to the immune system, in lung tissue.

But these cells decay too quickly to be useful in developing a vaccine, says Professor Wakim.

"What we have found that these same cells exist in the nasal tissue, they persist for a very long time.

"I guess it's not surprising that they are there but we are the first ones to show that they are there," said Prof Wakim.

Subsequent studies on mice showed that these CD8 T cells have the capacity to "quench an influenza virus" before it can actually move down into the lung.

"We found a population of these cells that, unlike their cousins in the lung, persisted for a very long time, and that they could block inhaled virus particles from reaching the lung, preventing severe flu-related lung infections."

"We are now trying to work out the best way to lodge these flu-fighting resident memory T cells in the nasal tissue, with the ultimate goal of developing a new vaccine that can provide long term protection against flu viruses," Prof Wakim said.