A FLU vaccine that is sprayed into the nose seems to protect against strains other than those it was designed for. Its developers are trying to find out why. “We don’t understand at all why this happens,” says Harry Greenberg of Stanford University, California. “But if we did we might be able to apply the same trick to other vaccines.”
Such vaccines could have huge health implications. Many viruses are able to evolve and change the surface proteins they present to the immune system, so that vaccine manufacturers have trouble keeping up. Conventional flu vaccine, for instance, contains killed vaccine…
