An mRNA vaccine against all 20 known influenza virus subtypes has been developed. Initial tests conducted in animals show that the vaccine reduced signs of illness and protected them from death, even when the animals were exposed to flu viruses unrelated to the one used to make the vaccine.

The work suggests that the vaccine could offer broad protection against all strains of flu, including the lethal ones. Given the risk of flu pandemics and the deaths caused by seasonal flu, this could be an incredible tool in our medical arsenal.

“The idea here is to have a vaccine that will give people a baseline level of immune memory to diverse flu strains, so that there will be far less disease and death when the next flu pandemic occurs,” study senior author Dr Scott Hensley, a professor in of Microbiology at in the Perelman School of Medicine, said in a statement.

The vaccine uses the same mRNA technology successfully demonstrated in COVID-19 vaccines. It uses immunogens: antigens that stimulate an immune response. The RNA has the code of a key (but harmless) flu protein shared among the 18 types of Influenza A viruses and the two types of Influenza B. Once injected, cells in the area produce the protein and the immune system believes it is under attack, producing specific antibodies.

So, the next time a flu virus enters the organism, the immune system will be able to react more quickly. The vaccine is not a sterilizing one – it doesn’t stop you from catching the flu ever again. Instead, it primes your body so that if you do catch the flu, it would be a lot less severe.

“It would be comparable to first-generation SARS-CoV-2 mRNA vaccines, which were targeted to the original Wuhan strain of the coronavirus,” Hensley said. “Against later variants such as Omicron, these original vaccines did not fully block viral infections, but they continue to provide durable protection against severe disease and death.”

The team is keen to put this to the test in humans. They are now designing human clinical trials to see how the vaccine behaves for us. If successful this vaccine could be employed to curb the spread and the danger of flu in all age groups, from children to old people.

“We think this vaccine could significantly reduce the chances of ever getting a severe flu infection,” Hensley added.

The findings are published in the journal Science.