HilleVax Inc.'s stock HLVX, -0.28% cratered 89% early Monday, after the biotech said it would discontinue development of a vaccine against norovirus for infants after a trial missed its main goals. The Boston-based company said the Phase 2b trial of HIL-214 for infants of about five months of age failed to meet its primary endpoint of efficacy against moderate or severe acute gastroenteritis events due to GI.1 or GII.4 norovirus genotypes.