A mRNA universal flu vaccine is in early stages of development

Researchers from the University of Pennsylvania have developed a universal flu vaccine using nanoparticle encapsulated mRNA. 

Claudia Arevalo from the University of Pennsylvania, PA, USA, and colleagues have produced a mRNA lipid nanoparticle vaccine, which could be used as the basis for such a universal vaccine. The vaccine contains antigens from 20 subtypes of influenza A and B viruses, in other words, all known strains of the virus.

When tested in animals the vaccine triggered the production of cross-reactive and subtype-specific antibodies and protected against symptoms and death after infection. This result was seen after infection with strains of the virus with both matched and mismatched antigens.

Previous attempts at a universal vaccine have contained antigens for each particular subtype, but with Arevalo’s vaccine a smaller number of antigens are used, which are specific to multiple strains, therefore still protecting against all known forms of the viruses.

During the COVID-19 pandemic, Pfizer and BioNTech and Moderna made breakthroughs in using mRNA to develop effective vaccines against SARS-CoV-2. This step forward in technology, proven to be safe and effective, has led to increased research into the use of mRNA.

Arevalo’s team decided to build on this success and combine it with nanotechnology to develop 20 different mRNAs encapsulated in nanoparticles. Each particle encoded for a different hemagglutinin antigen, which helps the virus enter cells.

In mice, antibody levels remained stable for up to 4 months post vaccination. The results, published in Science, were more promising than shown by previous types of multivalent vaccines.

Questions regarding the probability of a vaccine that contains antibodies to virus strains that have not yet been seen in circulation in humans obtaining approval are valid, spurring further discussions surrounding how we approach protecting against viruses of pandemic potential in the future.