Study Overview: This study checks how well a new medicine called CDI-988 works against a virus called Snow Mountain Virus, which is a type of norovirus. People in this study will either get CDI-988 or a placebo (a pill with no medicine) for 5 days. They won’t know which one they’re getting. Researchers will see if CDI-988 helps reduce symptoms like diarrhea or vomiting and check the amount of virus in stool samples. They'll also look at side effects and how much of CDI-988 stays in the blood, known as *pharmacokinetics*. Key Points:

• Study Duration: Participants will be in the study for about 5 days.
• Eligibility: Must be healthy, 18-49 years old, and know their FUT2 status.
• Compensation: Participants may receive payment for their time and effort.

Participation Requirements: Participants must be healthy adults aged 18-49, with no history of norovirus issues or recent vaccinations. They should not have any chronic stomach problems or recent illnesses. It's important to weigh more than 45 kg and have a normal BMI. Participants should not be on certain medications, especially those affecting the immune system.