On Jun. 3, 2025, researchers at University of Pittsburgh School of Public Health and the Pennsylvania State University.A new type of mRNA vaccine is more scalable and adaptable to continuously evolving viruses such as SARS-CoV-2 and H5N1, according to a study by The study was published in NPJ Vaccines.

Though highly effective at inducing an immune response, current mRNA vaccines, such as those used to prevent COVID-19, present two significant challenges: the high amount of mRNA needed to produce them and the constantly evolving nature of the pathogen. 

To address these challenges, the researchers created a proof-of-concept COVID-19 vaccine using what’s known as a “trans-amplifying” mRNA platform. In this approach, the mRNA is separated into two fragments—the antigensequence and the replicase sequence—the latter of which can be produced in advance, saving crucial time in the event a new vaccine must be developed urgently and produced at scale.

Additionally, the researchers analyzed the spike-protein sequences of all known variants of the SARS-CoV-2 for commonalities, rendering what’s known as a “consensus spike protein” as the basis for the vaccine’s antigen.

In mice, the vaccine induced a robust immune response against many strains of SARS-CoV-2.