Research from the Netherlands, using mice, has revealed that a new type of mRNA vaccine is safe to use in the body, highlighting its potential in future immunisations against pathogens.

Self-amplifying mRNA (SAM) vaccines are an advanced form of mRNA vaccine that not only contain the genetic code for a viral protein to be produced, like the mRNA vaccine used for immunising against Covid-19, but also a replicating mechanism for that protein, boosting immune response.

This study – published in Molecular Therapy – aimed to address safety concerns about SAM vaccines potentially recombining with other viruses, which can happen because it contains parts of a type of virus called an alphavirus.

To test this, researchers at EARA member Wageningen University injected these SAM vaccines into healthy mice. They monitored the animals for the creation of chimeric viruses, which would indicate recombination with other viruses, potentially creating a stronger hybrid virus.

However, this was not observed, with Gorben Pijlman, lead researcher at Wageningen, saying: “The risk of recombination in real-world scenarios appears negligible, making SAM vaccines safer than initially thought.”

These findings suggest that SAM vaccines can be a key tool in developing new mRNA vaccines that promote stronger and more effective immunisation, without compromising human health.