GSK Advances mRNA Flu Vaccine to Phase III After Positive Phase II Data
GSK sits 31% above its 52-week low of $38.63.
Summary
GSK announced positive phase II data for its mRNA seasonal flu vaccine candidate and plans to start a phase III efficacy trial in September 2026.
Key Events · Product Development and Regulatory · GSK
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Positive Phase II Flu Vaccine Data
GSK's mRNA flu vaccine candidate showed higher immune responses against all influenza strains tested compared to licensed standard dose and high dose inactivated flu vaccines in younger and older adults respectively.
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Phase III Trial to Start September 2026
GSK intends to start a phase III efficacy trial in September 2026, making this the first phase III trial of an mRNA flu vaccine targeting both haemagglutinin (HA) and neuraminidase (NA).
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FDA Fast Track Designation
The FDA granted Fast Track designation for the vaccine candidate in July 2026 for the targeted age indication.
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Differentiated Mechanism
Unlike licensed flu vaccines that primarily target HA, GSK's candidate is designed to also target NA, which growing evidence suggests could improve protection, illness severity, and transmission.
Analysis · GSK · Life Sciences
GSK's mRNA seasonal flu vaccine candidate showed higher immune responses than licensed standard and high dose flu vaccines in younger and older adults respectively. The company will start a phase III efficacy trial in September 2026, making this the first phase III trial of an mRNA flu vaccine targeting both HA and NA antigens. This is a meaningful pipeline milestone for GSK's respiratory vaccines franchise, though the candidate remains years from potential commercialization.
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At the time of this filing, GSK was trading at $50.47 on NYSE in the Life Sciences sector, with a market capitalization of approximately $100.7B. The 52-week trading range was $38.63 to $61.70. This filing was assessed with positive market sentiment and an importance score of 7 out of 10.