With the flu season well underway, many of us will be contemplating a trip to the doctor’s surgery for our annual flu shot. However, recent research suggests that by targeting a preserved region of a protein found in many influenza strains, it might be possible to create a broader flu vaccine that would effectively end the need for these yearly vaccinations.

Ironically, patients who survived infection with the 2009 H1N1 pandemic flu strain developed antibodies capable of protecting the host from a variety of flu strains, which scientists suggest might aid the creation of a universal flu vaccine.

Developing a universal vaccine

Researchers at the University of Adelaide have gone further and trialed a synthetic universal flu vaccine in mice. By applying synthetic peptides to the nasal passages of mice, they were able to trigger an immune response that targeted both influenza A and B-type viruses. This resulted in 100% protection against a laboratory virus called H3N2, and 20% protection against the ‘bird flu’ H5N1 virus – broadly similar to levels achievable using existing drugs.

Delivering vaccines via nasal spray

Other research postulates the use of nasal sprays to deliver such vaccines effectively and painlessly. Mucosal surfaces in the nose typically tend to exhibit a low immune response, but by combining standard vaccines for respiratory viruses (not just the flu) with a chemical that stimulates a nasal mucosa immune response, it is possible to induce high levels of protection in mice.

Nasal spray devices must ideally generate droplets within a specific size range (approx 20-120 μm) to facilitate deposition of the active pharmaceutical ingredient where it will have most effect. By modifying the viscosity of the formulation, or the design of the device, droplet size of the delivered dose can be fine-tuned to ensure the effective administration of a nasal vaccination.

The obvious benefits that non-injectable delivery of a universal flu vaccine might bring both healthcare givers and receivers, make this concept a target for pharmaceutical manufacturers.