A better, more effective flu vaccine is a matter of when—not if—says Dr. Gregory Poland, director of Mayo Clinic's Vaccine Research Group. The National Institutes of Health is testing an experimental universal flu vaccine with the goal of providing high-efficacy, long-lasting protection against influenza viruses.

"The idea behind a universal flu vaccine is to say we have to get out of the way we're currently doing it," says Dr. Poland. "Every year, different viruses circulate. Every year, we make new vaccines. And even while we're giving those vaccines, the flu virus is mutating. In the beginning of the flu season, the vaccine may work very well. By the end of the flu season, it may not work very well, and that's because the viruses are mutating."

Watch: Dr. Gregory Poland explains universal flu vaccine.

A goal of the universal flu vaccine is provide protection against multiple influenza strains. Dr. Poland says the hope will be to give the vaccine once for long-lasting protection.

"The first step is to say we want 75% efficacy for at least 12 months, and then we will work our way to saying we will give a dose of that flu vaccine and you'll be protected for 5 to 10 years. Then we may have to give a different dose 10 years later, and in that interim time period you have protected against the flu viruses that are likely to circulate and make you sick, with one exception."

"In the first iteration of this, the flu vaccine will be built around the virus that really causes the most number of severe illnesses, deaths, hospitalizations, and that's influenza A virus," says Dr. Poland. "It won't cover the B virus probably in the first phase."

"This will be a game-changer," says Dr. Poland. "Last year, almost a million Americans were hospitalized and 90,000 Americans died as a result of the flu."

Don't forego getting your annual flu vaccine yet. The universal flu vaccine is in clinical trials and it will likely be years before it is available to the public. The Centers for Disease Control and Prevention recommends that all people 6 months and older receive an annual flu vaccine.