The study includes a single intravenous (IV) infusion of the study drug and consists of a screening period (4 weeks), a double-blind, placebo-controlled period (12 weeks), and a safety follow-up period (8 weeks). Participants confirmed eligible will be randomized (1:1:1) to receive a single IV infusion of either eptinezumab 300 milligrams (mg) dose (weight adjusted; targeting adult exposure after 300 mg IV), eptinezumab 100 mg (weight adjusted; targeting adult exposure after 100 mg IV), or placebo at randomization visit. The doses will be adjusted for the participant's body weight.