Just one dose of a new vaccine candidate may protect against multiple strains of flu. The corresponding research was published in PNAS by researchers in the National University of Singapore and Monash University, Australia.
Seasonal influenza, also known as ‘flu’, affects between 13 and 100 million people every year, and results in 3-5 million cases of severe illness and between 300,000 and 600,000 deaths globally.
Due to the flu’s high mutation rate, vaccines for it need to be updated every year, resulting in low take-up by the general public and poor coverage due to inaccurate predictions of circulating strains. To resolve these issues, researchers are developing a universal vaccine that needs only to be taken once.
Until now, they have identified a handful of potential candidates. One is the 24-amino acid ectodomain of M2 protein- ‘M2e’- as it shares a conserved sequence with almost all known human influenza A strains- the only influenza strains known to cause flu pandemics. However, previous research found it was limited due to a lack of sustained immune response.
In the current study, researchers developed a vaccine based on a new way to deliver M2e to immune cells. In mouse models, a single injection of the vaccine yielded a sustained anti-M2e antibody response and an enhanced protective response against multiple strains of flu. They further found that the vaccine significantly enhanced pre-existing immunity from prior exposure to flu.
The researchers say that their novel approach could reduce the amount of M2e vaccine antigen- the substance that triggers the body’s immune response against itself- and number of injections needed for lasting protection. It also could also remove the need for strong adjuvants- substances that enhance the body’s immune response to antigens- thus reducing potential side effects.
The team suggests that the new approach could be adapted for other diseases too. To this end, they are currently working on a COVID-19 vaccine candidate based on the same approach.