Pfizer and BioNTech’s mRNA vaccine for influenza and COVID-19 began phase 1 trials in November, joining the growing number of jabs aiming to capitalize on mRNA technology. The trials will administer Pfizer’s quadrivalent influenza vaccine (qIRV (22/23)), encoding the hemagglutinin glycoproteins of four influenza strains, and the companies’ Omicron-tailored bivalent COVID-19 vaccine that targets the original SARS-CoV-2 strain and BA.4 and BA.5 variants. Moderna is also in phase 1/2 trials with a vaccine (mRNA-1073) combining its quadrivalent influenza and original-strain COVID vaccines (mRNA-1273). Other mRNA-made jab combinations in phase 1 trials include Moderna’s influenza, COVID-19 and respiratory syncytial virus vaccine (mRNA-1230).

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Pfizer and Moderna, as well as heavyweights Sanofi Pasteur, partnered with Translate Bio, and GlaxoSmithKline, working with CureVac, are also pursuing single mRNA flu vaccines. Yet mRNA-made flu shots have yet to match the efficacy of COVID-19 mRNA vaccines. The upside of mRNA technology is, however, that it is substantially faster than traditional methods, such as the decades-old egg-based production, newer cell-based systems or recombinant protein vaccine production — all of which require onerous purifications. Shorter production times mean that vaccines can be made closer to the start of flu seasons than current vaccines, allowing better matching to the year’s circulating strain. mRNA technology also allows large numbers of antigens to be incorporated — Moderna announced it is investigating one-time universal flu vaccines that would also allow cheap, local manufacture.