Influenza kills between 250,000 and half a million people annually, according to the World Health Organization. And major pandemics are capable of causing millions of deaths across the globe, much like the Spanish flu outbreak of 1918, which was responsible for an estimated 30 to 50 million deaths worldwide.

Existing vaccines for the flu are effective, but not perfect. They rely on antibodies to fight the infection, but they only target the surface characteristics, which doesn’t stop the virus from adapting and mutating — thus more devious strains develop, creating the need to constantly create and administer upgraded vaccines.

But a new universal flu vaccine developed by a research team at the University of Nebraska-Lincoln could be the solution. The vaccine combines ancestral genes from four major influenza strains and "appears to provide broad protection against the flu," according to a new study published in the journal Scientific Reports.

Researchers gave mice their new vaccine and then exposed them to lethal doses of various flu viruses. But 100 percent of the mice survived. In comparison, mice that received the current flu vaccine all got sick or died.

"The ultimate goal is to be able to vaccinate once and provide lifelong protection," lead researcher Eric Weaver, an assistant professor in the School of Biological Sciences at the University of Nebraska-Lincoln, said in a statement. "Our current influenza vaccine programs and technologies reduce influenza infections and hospitalizations by 4.75 percent and 6.9 percent, respectively. There is no doubt that there is a need for more effective vaccine technologies."

However, some experts say it may be 2020 or 2025 before a universal flu vaccine is available, according to UNL.

Another approach to the universal vaccine

In 2013, researchers discovered a “blueprint” for a universal vaccine that could protect against all strains of seasonal influenza, and remarkably, even future viruses that are as yet unknown.

During the 2009 swine flu pandemic, scientists monitored the health condition of more than 300 students and staff at the Imperial College London. They discovered that people who were minimally affected by the flu had a stronger presence of CD8 T cells in their blood at the start of the pandemic; CD8 T cells are naturally occurring immune cells the body uses to fight viruses.

Professor Ajit Lalvani, from the National Heart and Lung Institute at Imperial College London, who led the study, said that a vaccine that made the body produce more of these cells had the potential to be “the holy grail” and could offer a universal vaccine effective against all strains of flu.

“The immune system produces these CD8 T cells in response to usual seasonal flu,” Lalvani said. “Unlike antibodies, they target the core of the virus, which doesn’t change, even in new pandemic strains. The 2009 pandemic provided a unique natural experiment to test whether T cells could recognize, and protect us against, new strains that we haven’t encountered before and to which we lack antibodies,” reports The Independent.

“We already know how to stimulate the immune system to make CD8 T cells by vaccination. … Now that we know these T cells may protect, we can design a vaccine to prevent people getting symptoms and transmitting infection to others,” Lalvani added. “This could curb seasonal flu annually and protect people against future pandemics.”

The results were published in the journal Nature Medicine.

Editor's note: This story has been updated since it was originally published in September 2013.

Is a universal flu vaccine in your future?
Imagine a vaccine that provided life-long protection against any strain of the flu virus. New research makes it closer to reality.