- Abnormalities on physical examination suggestive of conditions that may pose an increased risk to the subject; abnormal electrocardiogram results (excluding benign conditions); and Grade 1 or higher abnormalities in vital signs at screening and Grade 2 or higher abnormalities in vital signs at check-in based on a modified version of the FDA Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventive Vaccine Clinical Trials.