The misery of the common stomach flu may be about to end. Pharmaceutical company Moderna has launched a large Phase III trial to test a vaccine against norovirus, a common and sometimes dangerous source of food poisoning.
Moderna’s Nova 301 trial is expected to begin this year, following the first dose given to a volunteer last September. About 25,000 18-year-old volunteers are expected to enroll in a randomized, double-blind, placebo-controlled study, which will take two years to complete. People all over the world will be able to participate in the study, including much of the US
Norovirus is the leading cause of foodborne illness in America, accounting for nearly 20 million cases each year. Most cases of norovirus are short-lived—if the flu is not severe—with symptoms such as diarrhea, vomiting, and a flu-like illness lasting three days. For many, it is a painful but manageable ordeal. However, a large number of people seek medical care, resulting in more than two million doctor visits and nearly half a million emergency room trips each year. In rare cases, the infection can be severe enough to cause hospitalization or even death. About 100,000 Americans are hospitalized with norovirus, and 900 die from it every year. It is a major problem in parts of the world with weak sanitation and health systems.
“Norovirus is a major public health problem that affects millions of people around the world every year, leading to serious symptoms and, in some cases, hospitalization,” said Stéphane Bancel, CEO of Moderna, in a statement. “By advancing our investigational norovirus vaccine to a pivotal Phase 3 study, we are one step closer to providing a new tool to prevent infection with this highly contagious virus, which places a huge burden on health systems around the world.”
Although norovirus has long been a thorn in humanity’s side, the urgency of a vaccine is now quite high. Following a brief lull during the first period of the pandemic, norovirus has made a comeback in the U.S. During the last half of 2024, approximately 500 norovirus infections have occurred, a significant increase compared to the previous year. And this winter norovirus season is on track to be the worst in more than a decade.
Scientists have struggled to develop an effective norovirus vaccine. Historically, we have not been able to grow the virus in the lab or in small animals, which hinders our study of it. The virus is also naturally strong in our defenses. There are several types of norovirus that cause disease circulating at any given time, and recent infection with one type does not necessarily protect against others. Our natural immunity to a species also tends to wane over time, perhaps lasting a few months for others.
But recently, scientists have been able to create effective lab models to study norovirus, and have developed promising vaccine strategies. The Moderna vaccine, for example, is trying to create immunity by training the body to target virus-like particles (VLPs) that are very similar to norovirus but contain no actual virus. The candidate uses the same basic mRNA technology used in Moderna’s covid-19 vaccine to achieve this. mRNA vaccines stimulate immune cells to produce target proteins that are then recognized by the immune system as a potential threat (in this case, norovirus VLPs).
The company’s candidate is code-named mRNA-1403, and is designed to induce immunity to at least three common strains of norovirus, hoping to ensure widespread protection. Although norovirus is a bad experience for everyone, it is more likely to cause serious illness in vulnerable people such as people with weakened immune systems and the elderly. Therefore the majority of research volunteers (20,000) will be over 60 years of age. Some companies are testing their own norovirus vaccines on children, however.
There are over 250 Nova 301 test sites worldwide, and over 100 are located in the US alone. Participants need to be in good general health (this can include having well-controlled chronic health conditions), and have no recent history of stomach ailments, among other criteria. The main part of the study is scheduled to last two years, with the final results expected in May 2027. Those interested in participating can take the survey created by Moderna here.