Norovirus, a highly contagious virus known for causing stomach flu-like symptoms, continues to present significant challenges globally. With its rapid evolution and complex genetic structure, norovirus remains a formidable adversary for researchers. The virus affects millions annually, leading to significant health and economic impacts. Currently, efforts are underway to develop an effective vaccine, though hurdles remain. Companies like Moderna and Vaxart are at the forefront of this scientific endeavor, with vaccine candidates in various stages of testing.
Norovirus is notorious for its resilience and adaptability. The virus can survive on surfaces for days or even weeks, making it exceptionally difficult to eradicate. Despite this, most individuals recover from norovirus within one to three days, though the virus is responsible for approximately 200,000 deaths worldwide each year, including about 900 in the United States. The economic burden is also substantial, costing the U.S. an estimated $2 billion annually.
Outbreaks of norovirus are frequent due to its multiple dominant types and dozens of subtypes. Each year, between 19 and 21 million cases occur in the U.S. alone, resulting in over 100,000 hospitalizations. The virus's hardiness presents additional challenges as it cannot be eliminated by hand sanitizer or soap and water. Nevertheless, preventive measures such as thorough hand washing, cooking shellfish adequately, washing produce before consumption, cleaning contaminated surfaces, and using hot water for laundry can reduce the risk of infection.
“Norovirus is one of those stubborn, highly contagious, moving target viruses with complex genetic evolution that spawns—and will continue to spawn—a lot of variants,” – Mark Cameron, PhD
The development of a norovirus vaccine is underway, with Moderna testing a candidate in human participants. However, experts caution that this vaccine may not resolve all issues posed by the virus. Norovirus's rapid evolution complicates research efforts and creates significant obstacles in developing an effective vaccine.
“It really is evolving extremely rapidly, and that’s a big problem,” – Patricia Foster, PhD
One challenge facing vaccine development is the absence of a reliable preclinical model that allows affordable testing to ensure a candidate is on the right path.
“But there are other reasons a norovirus vaccine isn’t commercially available yet, including [the fact that] there isn’t a solid preclinical model to affordably test whether a particular vaccine candidate is on the right track.” – Mark Cameron, PhD
In addition to Moderna's efforts, Vaxart has made noteworthy progress with their norovirus vaccine tablet recently completing phase I clinical testing. However, several regulatory hurdles must be cleared before these vaccines can become publicly available.
“Viruses all have different structures, and some of them have kind of a fatty envelope around them that helps them infect your cells,” – Amesh Adalja, MD
This inherent complexity in viral structures further complicates vaccine development efforts. In the meantime, maintaining effective hygiene practices remains crucial in preventing the spread of norovirus.
“Washing your hands works because you’re washing off [the virus],” – Patricia Foster
“Wash your hands before you eat and after you go to the restroom,” – Ming Tan, PhD
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