A vaccine that combines genes from four strains of influenza may one day serve as a universal flu shot, researchers said in November.

The shot, developed by a team at the Nebraska Center for Virology, helped mice survive lethal doses of nine different flu viruses. Mice that received traditional vaccines or nasal sprays became sick and died.  

It’s unclear whether the shot could work in humans, but it’s a positive step toward an inexpensive vaccination that provides lifelong protection, said lead researcher Eric Weaver, Ph.D.