RecruitingDrug trialA Study to Evaluate the Efficacy, Safety and Pharmacokinetics of CDI-988 in Healthy Adults After Challenge With Snow Mountain VirusParticipants in this study will be given either CDI-988 or placebo orally before receiving a norovirus challenge virus and continuing for 5 days. Participants will not know whether they are getting placebo or CDI-988. The study will evaluate how well CDI-988 compared to placebo can reduce the incidence of clinical symptoms after a challenge with norovirus. The amount of virus in stool samples will be measured over time. Side effects and pharmacokinetics (the amount of CDI-988 in blood) will also be measured.