(HealthDay News) — Two doses of an intranasally delivered norovirus virus-like particle (VLP) vaccine with adjuvants (chitosan and monophosphoryl lipid A), provides protection against challenge with a homologous Norwalk virus in healthy adults, according to a study published in the Dec. 8 issue of the New England Journal of Medicine.

Robert L. Atmar, M.D., from the Baylor College of Medicine in Houston, and colleagues investigated the safety, immunogenicity, and efficacy of an investigational, intranasally delivered norovirus VLP vaccine with adjuvants, in the prevention of 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 randomized to receive two doses of either 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 were included in the per-protocol analysis.

The investigators found that nasal stuffiness, nasal discharge, and sneezing were the most commonly reported symptoms after vaccination. Patients in the vaccination and placebo groups had a similar frequency of adverse events. In total, 70% of individuals in the vaccination group showed a Norwalk virus-specific IgA seroresponse. Vaccination significantly reduced the frequency of Norwalk virus gastroenteritis and infection, with gastroenteritis occurring in 69 versus 37% of placebo and vaccine recipients, respectively, and infection occurring in 82 versus 61% for placebo and vaccine recipients, respectively.

“This norovirus VLP vaccine provides protection against illness and infection after challenge with a homologous virus,” the authors write.

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

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