sciencehabit writes: Two groups of researchers have created vaccines that may lead to a universal flu shot that could protect against every type of flu. Every year millions get a flu shot but with thousands of strains that mutate and evolve across seasons, no one shot can protect against them all. Sciencemag reports on the research: "When the teams vaccinated mice, both groups saw full protection against H5N1, a lethal influenza strain distantly related to H1N1. In both studies, mice that did not receive the stem-derived vaccine died, but vaccinated mice all survived. In further experiments, the nanoparticle-anchoring vaccine showed partial protection in ferrets, whereas the other vaccine showed partial protection in monkeys. Two of the six vaccinated ferrets fell ill and died, compared with a 100% mortality rate for the unvaccinated ferrets. None of the monkeys died, but those that were vaccinated had significantly lower fevers than their nonvaccinated companions."