Vaxart has dosed the first participant in the Phase II clinical trial of its oral tablet bivalent norovirus candidate.

The dose-ranging trial has been designed for assessing the safety and immunogenicity of the oral norovirus vaccine in healthy adults.

It will also identify a vaccine dose for a potential Phase III clinical trial.

Nearly 135 healthy adult participants are expected to be enrolled at three US sites.

The initial ten participants in the trial will receive an open label, high-dose vaccine, and the remaining will be randomised and given a high- or low-dose vaccine or a placebo.

Immunogenicity and safety of the norovirus vaccine candidate to determine the dose levels for Phase III development are the trial’s primary endpoints.

The company is expected to report topline data from the Phase II trial in the middle of this year.

Vaxart chief medical officer Dr James Cummings said: “Initiating the Phase II clinical trial of this candidate is an important achievement toward our 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.

“Data from the Phase II trial will inform our further clinical development strategy for this promising vaccine candidate, targeting a market estimated at more than $10bn in the United States alone.”

The company stated that its bivalent vaccine candidate showed robust immunogenicity, with a 78% IgA ASC response rate for the GI.1 strain and 93% for the GII.4 strain.