The main goal of this study is to learn more about the safety of a drug called Lu AG22515. During the trial, healthy adult participants will receive a single dose of Lu AG22515 or a placebo (normal saline solution).

Inclusion Criteria:

• Body mass index (BMI) ≥18.0 and ≤32.0 kilograms (kg)/square meter (m^2) and weight between 55 and 110 kg (both inclusive) at screening.
• Fully vaccinated against COVID-19, as evidenced by presentation of a vaccine card. The last administration of the COVID-19 vaccination must be received a minimum of 30 days and maximum 6 month prior to dosing in this study.
• Medically healthy with no clinically significant medical history, physical examination and neurological assessment, laboratory profiles, vital signs, or electrocardiograms (ECGs), as deemed by the principal investigator (PI) or designee.

Part C only:

• The participant is Japanese, defined as being born in Japan and having four Japanese grandparents as well as living a Japanese lifestyle as confirmed by the Japanese lifestyle questionnaire.

Exclusion Criteria:

• Reported history of any illness that, in the opinion of the PI or designee, might confound the results of the study or poses an additional risk to the participant by their participation in the study.
• Received any vaccination in the last 30 days prior to Day 1.

Note: Other inclusion and exclusion criteria may apply.