Scientists have made significant progress toward the development of a “universal” flu vaccine that would potentially protect against every form of flu and would not need to be redesigned every year.
For researchers seeking to develop a better flu vaccine, the influenza virus has been a particularly difficult puzzle to solve because it rapidly changes surface proteins that the immune system needs to recognize in order to fight the invader. Consequently, a vaccine specifically designed to match the new surface proteins needs to be created anew each year.
The new research, published in the journal Nature Medicine, may help overcome this barrier and provide a single effective flu vaccine. Because the inner contents of the virus tend to be similar regardless of strain and year, a vaccine that would target the virus’s core could provide a solution. Scientists found that a particular type of immune cell, called a CD8 T cell, may be able to recognize influenza’s core and help muster a strong immune response against it.
To make this encouraging discovery, researchers examined blood and nasal swab samples from people infected during the 2009 swine flu pandemic. Swine flu had an entirely new outside shell that was not recognizable to most immune systems. However, the core of it was likely similar to other flu viruses. Researchers correlated symptoms of the flu with levels of T cells in the subjects’ blood, and found that people with more CD8 T cells had much milder symptoms.
One of the leaders of the study reported that newly identified fragments of material contained in the virus’s core could potentially be incorporated into a future vaccine. Researchers hope that exposing the body to this material could encourage proliferation of the CD8 T cells that help defend against symptomatic illness. This means that even if people were infected with the flu, they wouldn’t get nearly as sick and might be less contagious.
This discovery could have a huge impact on public health. The influenza virus kills an estimated 250,000 to 500,000 people worldwide every year. And when the virus unexpectedly mutates or the vaccine for that year is not a good match, epidemics or pandemics can arise that can kill many more. The Spanish flu pandemic in 1918, for example, is thought to have killed 3 to 5% of the world’s population.