My friend is waiting for 15 to 30 minutes after vaccine administration to ensure their safety and to promptly manage any adverse reactions, such as: *Allergic Reactions:* To identify and treat severe allergic responses (e.g., anaphylaxis), which, although rare, can occur shortly after vaccination. *Immediate Side Effects:* To monitor for fainting (vasovagal syncope), dizziness, or other immediate reactions, especially in individuals prone to anxiety or needle phobia. *Observation of Symptoms:* To check for localized reactions like swelling or redness, or systemic reactions like hives or difficulty breathing. *Quick Medical Intervention:* Ensures timely administration of emergency care, such as epinephrine, if a reaction occurs.