Norovirus Vaccine Pills Guard Against Winter Vomiting Bugs

In a few years, vaccine pills for norovirus that lower infection risk may become available, following promising trials where participants were deliberately exposed to the virus.

This highly contagious virus affects the stomach and intestines, resulting in vomiting and diarrhea, usually subsiding within a few days. “The economic impact is significant, with billions lost globally annually due to work absences and hospital visits,” stated Sarah Cady from Cornell University in Ithaca, New York.

Shawn Tucker from the biotech company Vaxart in San Francisco and his team have developed an oral vaccine that appears to increase IgA antibody levels, which can block noroviruses from infecting cells.

The current study involves 141 individuals aged 18 to 49, with half receiving the vaccine pill and the others a placebo. One month later, all participants ingested a high dose of the Gi.1 strain of norovirus in liquid form during quarantine. “Typically, to infect someone in a real-world scenario, you need to introduce 10 to 100 virus particles; we used 1 million particles,” Tucker explained, ensuring a sufficient infection rate.

Results showed that 82% of the placebo group became infected, whereas only 57% of those vaccinated were infected.

“Most people seem interested in receiving the vaccine if it can reduce risks by [25 percentage points] and lessen debilitating symptoms,” said Cady, who was not part of the research.

Additionally, vaccinated participants expelled considerably less stool and viral particles compared to the placebo group. This indicates the vaccine may help slow the virus’s spread, but further testing is needed, according to Cady.

Another analysis suggested the vaccine possibly works by boosting IgA antibodies in saliva, intestines, blood, and nasal passages.

However, the duration of this protection remains uncertain. More research is required to explore its effects on young children and the elderly, who are particularly vulnerable to hospitalization, said Cady.

Most human-infecting noroviruses belong to two clusters known as GI and GII. Based on preliminary findings, Tucker believes the GI.1 vaccine will likely offer protection against other closely related GI variants. The team is also working on vaccines that could shield against both GI and GII viruses.

If everything progresses positively, Tucker anticipates the GI.1 vaccine could be released in two to three years.