HilleVax (NASDAQ:HLVX) has disclosed the outcomes of its NEST-IN1 Phase 2b clinical trial, evaluating the HIL-214 vaccine in infants.

This randomized, double-blind, placebo-controlled trial aimed to assess the vaccine’s efficacy, safety, and immunogenicity among infants around 5 months old.

The trial recorded 51 primary endpoint events, split between 25 in the vaccine group and 26 in the placebo group, culminating in a vaccine efficacy of 5%.

The study concluded that HIL-214 did not meet its primary efficacy endpoint against moderate or severe acute gastroenteritis caused by GI.1 or GII.4 norovirus genotypes.

Moreover, the vaccine did not demonstrate clinical benefits across secondary endpoints.

While the safety and immunogenicity profile of HIL-214 aligned with initial expectations based on early trials and the first 200 subjects of NEST-IN1, HilleVax has decided to halt the vaccine’s development for infants.

The company is now considering the possibility of continuing the development of HIL-214 and its Phase 1 ready vaccine candidate, HIL-216, for adult use.