July 8 (Reuters) - Shares of HilleVax plunged as much as 87.6% to a record low of $1.75 on Monday after the biotech company said it will discontinue the development of its norovirus vaccine candidate for infants.

The vaccine, named HIL-214, showed an efficacy of only 5%, failing to meet the main goal in the mid-stage study conducted on more than 2,800 infants. It also did not show any clinical benefits across secondary goals of the study.

The study's main goal was efficacy against moderate or severe acute gastroenteritis events due to two norovirus variants, GI.1 or GII.4. But the company said the vaccine candidate's efficacy may have been hit due to multiple emerging types of the GII.4 strain.

HilleVax said it will discontinue further development of HIL-214 in infants, and will explore whether it can continue the same in adults.

The company said it will also examine whether to develop HIL-216, its other experimental vaccine, in adults after the trial failure.

HilleVax acquired the rights to develop and commercialize HIL-216 outside Greater China from Chengdu Kanghua Biological Products in January.

Despite the trial failure in infants, Leerink Partners analyst David Risinger was optimistic about HilleVax's two candidates in adults.

"Norovirus vaccines may offer protection for adults effectively as a booster, since virtually all adults have been exposed to norovirus in their lifetimes," Risinger said.

Norovirus is one of the leading causes of vomiting, diarrhea and other foodborne illnesses. It is estimated to cause about 685 million cases and roughly 200,000 deaths globally each year, according to the World Health Organization. Low-income countries are the worst hit.

In the United States, norovirus is responsible for nearly 1 million pediatric medical care visits annually, according to the U.S. Centers for Disease Control and Prevention.

Currently, Moderna and Vaxart are also developing norovirus vaccines. (Reporting by Puyaan Singh in Bengaluru; Editing by Shreya Biswas)