A novel intramuscular bivalent norovirus viruslike particle vaccine candidate-reactogenicity, safety, and immunogenicity in a phase 1 trial in healthy adults

Abstract

Background. Noroviruses are the most important viral causes of gastroenteritis-related morbidity and mortality. A randomized, double-blind, placebo-controlled study evaluated an adjuvanted bivalent intramuscular norovirus virus-like particle (VLP) vaccine. Methods. Forty-eight adults aged 18-49 years received either 2 doses containing genotype GI.1 VLP and a consensus GII.4 VLP or 2 doses of placebo. Doses (5 μg, 15 μg, 50 μg, or 150 μg of each VLP) were administered 4 weeks apart in the first stage. Subsequently, 54 adults, aged 18-49 (n = 16), 50-64 (n = 19), and 65-85 (n = 19) years, received 2 doses of vaccine containing 50 μg of each VLP. Total and class-specific antibody responses, as well as histoblood group antigen (HBGA) blocking antibody responses, were measured before and after each dose. Results. Local reactions were mainly injection site pain/tenderness, with no reported fever or vaccine-related serious adverse events. One dose of vaccine containing 50 μg of each VLP increased GI.1 geometric mean titers (GMTs) by 118-fold, 83-fold, and 24-fold and increased GII.4 GMTs by 49-fold, 25-fold, and 9-fold in subjects aged 18-49, 50-64, and 65-83 years, respectively. Serum antibody responses peaked at day 7 after the first dose, with no evidence of boosting following a second dose. Most subjects achieved HBGA-blocking antibody titers of ≥200. Conclusions. The vaccine was well tolerated and immunogenic. Rapid immune response to a single dose may be particularly useful in military personnel and travelers and in the control of outbreaks. Clinical Trials Registration. NCT01168401.