Flu shots may soon be a lot less painful for young children and older adults. Researchers say they have found a way to modify the nasal spray version of the vaccine to make it work for those two groups.
The nasal spray vaccine — which uses a weakened, but live, form of the virus — isn't approved for children younger than two years or adults older than 49. It's too strong to be safe for kids younger than two years, and it's too weak to trigger a useful response in adults older than 49. By the time people hit their fifties, most have been exposed to many strains of the flu over the years, so their immune systems already have lots of antibodies, and that makes it hard for the weakened virus to last long enough to provoke an immune response and generate antibodies against this year's strain of the virus.
It's easy to see why the nasal vaccine would be an improvement for the patients who are currently excluded from getting it: nobody likes needles, and they can be especially trying for the very young or the elderly. Andrew Pekosz and his colleagues at Johns Hopkins University's Bloomberg School of Public Health say they have found a way to modify the weakened virus used in the nasal vaccine, allowing them to weaken it enough for younger patients or strengthen it enough for older ones.
The researchers who created the current nasal vaccine made nine genetic mutations in the flu virus. After studying how the weakened virus behaves in cultures of nasal tract cells, Pekosz and his colleagues say they have figured out how to adjust those mutations to weaken or strengthen the virus as needed. Now, they're working with MedImmune, the company that makes FluMist, to develop the modified nasal vaccine, and they say it should be ready for testing in six to 12 months.