Every fall, millions of people roll up their sleeves for a flu vaccine, hoping to give their immune system a leg up on influenza. But the flu virus has thousands of strains that mutate and evolve across seasons, and the vaccine can’t guard against all of them. Now, two groups of researchers have independently created vaccines that lay the groundwork for a long-sought shot that could protect against every type of flu.
“This is really cutting-edge technology,” says Antonio Lanzavecchia, an immunologist at the Swiss Federal Institute of Technology in Zurich, who is unaffiliated with both studies. “There is still work to do, but this is a clear step forward and it’s headed in the right direction.”
Scientists develop flu vaccines by predicting the strains most likely to infect a population. They use year-round flu surveillance along with field reports from countries in the Southern Hemisphere to guess which strains are most likely to hit North America at the height of the flu season—December through March. But viral guesswork is a tricky business, and it’s impossible to be 100% right. This uncertainty makes for patchy protection, and as flu strains mutate over the course of the season, vaccines become less and less effective.