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Home » HilleVax Norovirus vaccine for infants fails in phase 2 clinical trial

HilleVax Norovirus vaccine for infants fails in phase 2 clinical trial

HilleVax, Inc., a Boston-based vaccine developer, announced that it was suspending its clinical trials for its norovirus vaccine candidate, HIL-214, for infants. You may be wondering why I’m writing about a failure, but it’s important to note that not every vaccine passes through clinical trials. Also, a vaccine for norovirus is incredibly important.

It’s also important to note that HilleVax, whose name references one of the leading researchers of vaccines, Maurice Hilleman, has not abandoned the norovirus vaccine candidate for adults.

Let’s review what norovirus is, why it’s important to prevent it, and what happened to the HIL-214 clinical trial for infants.

norovirus vaccine hillevax

What is norovirus?

According to the CDC, norovirus is a leading cause of acute gastroenteritis, an inflammation of the lining of the stomach and intestines. This can result in intense bouts of vomiting, diarrhea, nausea, and stomach cramps.

Symptoms of norovirus infection usually begin 12 to 48 hours after exposure — the symptoms are often sudden and very unpleasant, but most people will recover without further medical issues. Norovirus is extremely contagious, and anyone can become infected.

Although the virus spreads year-round, infections are most common during the winter months when people tend to spend more time gathered indoors, which makes it easier for infectious diseases like norovirus to spread quickly between individuals.

Infected individuals can shed billions of norovirus particles in their stool and vomit, and it only requires a few virus particles to infect another individual. People usually contract norovirus when the particles end up in their mouths. This can occur through person-to-person contact, consuming contaminated foods or liquids, or touching contaminated surfaces and then touching something that goes into your mouth like food. Moreover, norovirus may be transmitted by particles in the air such as in public restrooms.

According to the CDC, norovirus causes about 20 million cases of vomiting and diarrhea, 465,000 emergency room visits, 109,000 hospitalizations, and 900 deaths in the USA. Even though most people recover rather quickly from the infection, a large percentage of those who contract the disease will be hospitalized and about 1% of the hospitalized group will die.

shallow focus photography of microscope
Photo by Chokniti Khongchum on

Hillevax norovirus vaccine candidate clinical trial

HilleVax, Inc. announced the topline data results from the NEST-IN1 study, a phase 2b, randomized, double-blind, placebo-controlled clinical trial to evaluate the effectiveness, safety, and immunogenicity of the HIL-214 vaccine candidate in infants of approximately 5 months of age at the time of initial vaccination. The clinical study included sites in the United States and Latin America.

In the NEST-IN1 study, there were 51 primary endpoint events, with 25 in the vaccine arm (n=1,425) and 26 in the placebo arm (n=1,399), resulting in a vaccine efficacy of 5% (95% confidence interval; -64%, 45%). 

With a vaccine effectiveness of only 5% in children, the study did not meet its primary efficacy endpoint against moderate or severe acute gastroenteritis events due to norovirus. The researchers also found no clinical benefit observed across secondary endpoints.

Part of the reason that it may have failed is that the vaccine doesn’t prevent infection from new variants of norovirus that were spreading in Latin America.

HilleVax has decided to discontinue further development of HIL-214 in infants. However, they are proceeding with phase 2 clinical trials for HIL-214 and HIL-216 in adults, because preliminary results show a much higher vaccine effectiveness in preventing acute gastroenteritis from norovirus.


Norovirus is an incredibly dangerous disease for children and adults, so a vaccine to prevent the disease would be important for public health. Unfortunately, this particular norovirus vaccine from HilleVax did not show effectiveness in children.

The company is intending to proceed with clinical trials in adults, which may be successful.

The upshot of the results of this clinical trial is that safety and effectiveness are always tested in clinical trials, and when a vaccine candidate fails, further research stops. But more importantly, there is still hope that this vaccine will prove safe and effective in adults. We should see results in the not-too-distant future.

Michael Simpson
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