GSK hails positive results for its mRNA seasonal flu vaccine

By the Editorial Team · Wednesday, September 2, 2026

GlaxoSmithKline is moving its mRNA-based seasonal influenza vaccine candidate into a phase III clinical trial after mid-stage results showed superior immune responses compared to existing flu vaccines. This trial marks the first late-stage study of a dual-targeting mRNA flu vaccine, aiming to enhance protection and address the global burden of influenza, with the FDA granting it fast track status.

GlaxoSmithKline (GSK) announced it will advance its mRNA-based seasonal influenza vaccine candidate to a late-stage clinical trial following encouraging results from mid-stage data. The vaccine demonstrated stronger immune responses compared to both standard and high-dose currently approved influenza vaccines in younger and older adults.

GSK, one of Britain’s leading pharmaceutical companies alongside AstraZeneca, highlighted that this would be the first late-stage trial of an mRNA flu vaccine designed to target two key surface proteins of the virus: haemagglutinin (HA) and neuraminidase (NA). The company stated that this dual-targeting approach could enhance protection and reduce virus transmission.

Sanjay Gurunathan, head of vaccines research and development at GSK, emphasized the significance of these findings, noting that approximately one billion flu cases occur globally each year, with up to 650,000 deaths. He described the vaccine candidate as a substantial advancement in GSK’s mRNA programme and expressed anticipation for the imminent start of the phase III trial.

The groups at greater risk from seasonal influenza, such as older adults, pregnant women, and individuals with underlying health conditions, remain a primary focus for improved vaccination strategies. Although vaccination continues to serve as the main preventive measure, GSK acknowledged that the persistent disease burden underscores the need for next-generation vaccine approaches.

In July, the vaccine candidate received “fast track” designation from the U.S. Food and Drug Administration (FDA), a status that GSK indicated reflects the critical need for enhanced influenza protection. This move follows the recent U.S. approval of Moderna’s mRNA-based seasonal flu vaccine, mFlusiva, for use in people aged 50 and older, marking a notable milestone in flu vaccine development.

GSK’s decision to advance this vaccine candidate coincides with its broader strategy to initiate more than 20 late-stage clinical studies by the end of the year. This strategy aligns with a portfolio review conducted under the leadership of Luke Miels, who assumed the role of chief executive earlier in the year after serving as chief commercial officer. Miels succeeded Dame Emma Walmsley in the company's top position.

The company indicated plans to begin the late-stage trial for its mRNA flu vaccine within the current month. GSK shares closed up 18 pence, or approximately 1 percent, at £18.71½ following the announcement.

This article was reported by synthesizing coverage from multiple independent news outlets to present a balanced, unbiased account. Read about our editorial standards. Spotted an error? Let us know.