Influenza remains a global public health threat that cycles around the globe each year, based on seasons and strains. The viral varieties constantly mutate and change, making it a particularly elusive target for therapies and vaccines.

A team of scientists from the University of Georgia and Sano Pasteur have made a vaccine that protects an entire family of influenza strains, the H3N2, which was the dominant kind in Australia’s latest flu season that ended last month.

The team reports constructing 17 prototype vaccines based on genetic sequencing – and nearly complete immunity experimentally in mice and ferrets, they report in The Journal of Virology.

However, the swine-based H3N2 is just one of a myriad of other strains – and the viruses still maintain the ability to constantly adapt, meaning the universal vaccine is still a ways off, they add.

“This is progress, but we still have work to do before we get a truly universal flu vaccine,” said Ted Ross, of UGA, one of the lead authors. “We need to determine how many seasons this H3 COBRA vaccine will protect against all H3N2 viruses into the future in all populations of people.”

The group’s technique was the aforementioned COBRA (Computationally Optimized Broadly Reactive Antigen). The foundation of their synthesis: protein sequences from 6,340 human H3N2 viruses that were collected from 1968 to 2013. They then included sequences predicted to occur at secondary, tertiary, and quaternary levels.

Conventional vaccines attempt to guess the handful of most dominant strains coming in a single season. Even if the guess is correct, patients can still get sick, because of viral adaptability.

By contrast, the team’s new H3N2 coverage neutralized 100 percent of those viruses over a five-year period, they reported.

“What our group has developed is a vaccine that protects against all co-circulating strains of H3N2 viruses, so we might be able to one day replace the seasonal flu vaccine with this more broadly cross-protective vaccine,” Ross added.

Influenza kills an average of 36,000 people in the United States each year. Researchers continue to look for ways to attack the viruses – even through proteins long-lost in the process of evolution.