Scientists are moving closer to developing a new universal flu vaccine, and may possibly have it ready in as little as five years.
Researchers from the Imperial College London say they made a significant leap forward in developing a vaccine capable of protecting against every new strain of the seasonal flu.
"New strains of flu are continuously emerging, some of which are deadly, and so the Holy Grail is to create a universal vaccine that would be effective against all strains of flu," said lead investigator Ajit Lalvani, from the National Heart and Lung Institute at Imperial, in a press release.
Lalvani and his colleagues made the discovery after collecting blood from more than 340 volunteers during the 2009 H1N1, or "swine" flu pandemic that killed at least 18,500 people around the globe, reports CBS News.
For two years, blood donors were asked to mail in a nasal swab to a lab if they felt they were exhibiting flu-like symptoms. Scientists then confirmed if the person indeed had the flu.
Over time, the team found that people who had a type of virus-killing immune cell called CD8 T cells in their blood were more likely to avoid serious illness during the deadly pandemic. As a result, the British researchers theorized that prompting the body's immune system to create more CD8 T cells could lead to universal flu protection.
"We already know how to stimulate the immune system to make CD8 T cells by vaccination," Lalvani said. "Now that we know these T cells may protect, we can design a vaccine to prevent people getting symptoms and transmitting infection to others."
Since the flu virus' surface proteins are always changing, vaccine developers are constantly developing different flu vaccines each year to combat new emerging strains. However, the core of the flu virus changes very little from strain to strain, and previous research has suggested that some immune cells may already protect against this aspect of the flu.
Lalvani told the BBC that a universal flu shot was about five years away.