Norovirus, sometimes called the “stomach flu,” is the most common cause for viral gastroenteritis and affects people of all ages. Symptoms include stomach cramps, nausea, vomiting and diarrhea.

Millions contract Norovirus each year and thousands worldwide die, usually due to dehydration. In the United States, 570 to 800 people die each year as a result of Norovirus infection. Symptoms can often be most serious for the very young, elderly, or those with impaired immune systems. Many American infants and children require hospitalization.

The virus is transmitted by contact with a contaminated food or surfaces or through close contact with another infected person. Outbreaks have been documented in hospitals, military barracks, cruise ships, and nursing homes. Preventative measures such as good hand washing, cleaning potentially infected foods or surfaces, and avoiding touching one’s mouth after contacting the virus can lower one’s risk of contracting Norovirus.

While an infant rotavirus vaccine has proven very successful for more than a decade, no such vaccine was available to combat Norovirus (which accounts for 20 percent of all diarrheal cases worldwide). Enter Takeda Vaccines, Inc. and Vaxart, two companies taking the lead in Norovirus vaccine trials.

Takeda’s TAK-214 injectable vaccine is designed to cover the two Norovirus genogroups that cause a majority of illness in humans. The vaccine is in a phase IIb trial and being tested in healthy U.S. military volunteers 18–49 years old. The trial is evaluating the effectivness of the vaccine against moderate or severe acute gastroenteritis due to Norovirus. Outcomes from this trial have not yet been released (though the trial completed in August 2017).

Vaxart is developing an oral tablet vaccine (rather than injection). Its formulation showed encouraging results in phase 1 trials and moves to phase 2 in 2020.

Even if Takeda and Vaxart show evidence of safety and efficacy, however, the process for U.S. Food & Drug Administration clearance of a new vaccine can take years. Until that time, avoidance of the virus and hand hygiene are your best strategies to prevent vomiting and diarrhea.

Reviewed by Dr. Sara Connolly, May 2020