A prospective cohort study recently published in the journal Nature Medicine reveals that there might be a solution to rapidly changing and evolving flu viruses and strains after all.

Researchers from Imperial College London claim that they have made a "blueprint" for a universal flu vaccine which can be used as a preventive measure against several flu viruses and strains.

The study made use of 342 staff and students of the university who were afflicted with the 2009 swine flu pandemic. Each of the subjects had their health conditions monitored throughout the outbreak.

Specifically, the researchers compared levels of the CD8 T cells among subjects at the start of the pandemic. By the end of the outbreak, it was discovered that subjects who had higher levels of CD8 T cell levels developed milder symptoms compared to those who had lower levels of such T cells.

A CD8 T cell is a kind of virus killing immune cell found in the blood. It is a "set of naturally occurring immune cells" which the researchers deem highly potential to become a universal influenza vaccine.

"The immune system produces these CD8 T cells in response to usual seasonal flu. 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," said Professor Ajit Lalvani from the National Heart and Lung Institute at Imperial College London in a report.

Although a "blueprint" for the universal influenza vaccine is seemingly within grasp, the researchers admit that it might take time for the said vaccine to finally materialize.

According to a report by the BBC, the researchers admit that it is "generally harder to develop a T cell vaccine than provoke an antibody response."

"It's going to be a long journey from this sort of paper to translating it into a vaccine that works," said Professor John Oxford from Queen Mary University of London.

A universal influenza vaccine will greatly help curb annual seasonal flu, future flu outbreaks and pandemics.