Delivering flu vaccines straight into the lungs rather than through routine jabs could trigger a stronger immune response, according to a new study by researchers at the University of Melbourne.
Since the world is expected to be extremely short of vaccines in the event of flu pandemic, an effective way to deliver them is significant because it would economise on the quantity of each dose.
In the study, researchers found that lower doses of a seasonal flu vaccine delivered into the lungs of sheep gave better protection against flu than a higher standard dose that was injected into another group of sheep.
For the study, researchers delivered three different doses of flu vaccines (15, 5 and 1 micrograms) into the lungs of three groups of sheep using a bronchoscope, or tube. A fourth group of sheep was injected with standard 15-microgram flu vaccines.
"Lung delivery produced superior levels of antibodies in the lung (approximately 1,000 times more), where the influenza virus infects, than the injected vaccine. The antibodies produced in the blood and lung were able to block the ability of the virus to stick to the receptor it uses to infect cells, demonstrating they would be effective against infection," Sutton said.
Sutton added: "The generation of functional antibodies in the lung could potentially help reduce the spread of the infection by neutralising the virus before it can be breathed out by an infected person."
However, he noted that better ways to deliver vaccine directly into the lungs are required.
The study is published in Mucosal Immunology.