In February 2023 Vaxart announced that it had dosed its first subject in the Phase II clinical trial of an oral tablet bivalent norovirus candidate. The trial is a dose-ranging study to identify a vaccine dose for a potential Phase III trial. This step comes as public health leaders warn about rising cases of norovirus.  

An important moment 

Dr James F. Cummings, Chief Medical Officer at Vaxart, described the progress as an “important achievement” in the goal of “developing an oral tablet vaccine that may reduce the significant global health threat that norovirus poses to children and seniors”.  

“Results from the Phase Ib clinical trial in healthy adults demonstrate that this candidate stimulates robust IgA antibody secreting cells against the prevalent strains of two norovirus genotypes that cause the majority of norovirus disease”.  

Further data will guide the clinical development strategy for the vaccine candidate, “targeting a market estimated at more than $10 billion in the United States alone”.  

The trial and vaccine 

The bivalent vaccine candidate has already demonstrated “robust immunogenicity”. Going forward, the Phase II trial is expected to enrol around 135 health adults across three sites in the US. Top-line data will be delivered later in the year.  

The company states that its candidate is “differentiated from other norovirus vaccines in development” by its ability to generate “both systemic and mucosal immunity”, its oral delivery, and room temperature stability. These make it “much easier to distribute and administer”.  


Vaxart states that norovirus imposes “significant health and economic burdens”, causing 21 million illnesses each year in the US alone. In the UK, national surveillance data indicates that laboratory reports of the virus are 66% higher than the average for this time of year. UKHSA notes with concern that the biggest increase has been observed in patients over 65. 

Dr Lesley Larkin, Surveillance Lead, Gastrointestinal Infections and Food Safety (One Health) Division at UKHSA, remarked that levels are “currently the highest we have seen at this time of year in over a decade”.  

NHS Medical Director Professor Sir Stephen Powis is seeing a significant rise in the number of people in hospitals with norovirus.  

“It is a really unpleasant illness to catch.”  

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