WEDNESDAY, Dec. 7 (HealthDay News) — Two doses of an intranasal virus-like particle (VLP) vaccine, containing the  adjuvants chitosan and monophosphoryl lipid A, protect healthy adults against Norwalk virus, study results published in the Dec. 8 issue of the New England Journal of Medicine indicate.

Robert L. Atmar, MD, of Baylor College of Medicine in Houston, and colleagues assessed the vaccine’s safety, immunogenicity and efficacy in preventing acute viral gastroenteritis after challenge with a homologous Norwalk virus strain, genotype GI.1. A total of 90 healthy adults (aged 18 to 50 years) were randomly assigned to receive two doses of vaccine (47 participants) or placebo (43 participants). Eighty-four of the participants were subsequently inoculated with Norwalk virus and were monitored for infection and symptoms; 77 of these patients were included in the per-protocol analysis.

Vaccination significantly reduced the frequency of Norwalk virus gastroenteritis and infection, the researchers found, with 69% of placebo recipients experiencing gastroenteritis vs. 37% vaccine recipients. Norwalk virus infection occurred in 82% vs. 61% for placebo and vaccine recipients, respectively. Overall, 70% of people in the vaccination group showed a Norwalk virus-specific IgA seroresponse.

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Adverse events were similar among patients in the vaccination and placebo groups, with nasal stuffiness, nasal discharge and sneezing among the most commonly reported symptoms after vaccination.

“This study shows that it may be possible to use a vaccination strategy to prevent norovirus disease.,” the authors wrote.

The study was partially funded by LigoCyte Pharmaceuticals, which manufactures the Norwalk virus vaccine.

Atmar RL. N Engl J Med. 2011; 365:2178-2187.