This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Post exposure measles vaccine must be given within ----- days of exposure \nSelect and explain. \nA. 1, B. 3, C. 7, D. 10', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Post-exposure Measles Vaccine must be given within : 3 days of exposure IP for naturally accuired Measles : 10 days IP for Vaccine induced Measles : 7 days Measles outbreak control Measures Isolation for 7 days after outbreak of rash Immunization of contacts within 2 days of exposure. Immunoglobulin administration within 3-4 days of exposure (if vaccine is contraindicated) Prompt immunization at begining of Epidemic Ref: Park 25th edition Pgno : 161', 'role': 'assistant'}]