The viruses used to create the seasonal flu vaccine are traditionally grown in eggs using a time-consuming process. Therefore, health authorities must identify the strains they think will be most common in the next flu season. But they may not guess correctly, or virus strains may evolve, making the vaccine less effective.
Georgia State scientists said they have taken the first steps toward a universal vaccine, creating an influenza shot that protected mice against multiple strains of influenza A.
Traditional vaccines target the exterior head of the flu virus’ surface protein, hemagglutinin (HA), to elicit protective immunity. Because the head is “highly variable” and is different for every flu virus strain, the Georgia State team focused on the stalk, another part of the surface protein, to achieve protection from all strains, researchers said in a statement.
The researchers vaccinated mice with two doses of a nanoparticle injection that targeted the stalk. The mice were then exposed to four different strains of flu virus, including H1N1 and H3N2, which turn up in a typical flu season. The vaccine protected mice against lethal exposure and also decreased the amount of virus in the lungs.
"This vaccine is composed of very conserved domains. That's the reason why the induced immunity can offer universal protection," said Lei Deng, first author of the study and a postdoctoral researcher in the Institute for Biomedical Sciences at Georgia State, in the statement.
Deng added that further studies need to be done to determine how long-lasting the vaccine might be in people. Next, the team plans to test the vaccine in ferrets because they are susceptible to human flu viruses and their lungs are similar to human lungs.
The news comes as the U.S. battles a “moderately severe” flu season—flu is widespread in every state except Hawaii, The New York Times reported. The efficacy of this year’s vaccine can’t be calculated because flu is still spreading, but experts expect it to level out at about 30%. The seasonal flu shot lowers the risk of falling ill by 40% to 60%, according to the CDC.