This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'Pneumococcal vaccination is indicated in   a) Postsplenectomy  b) Sickle cell anemia  c) HIV  d) After radiotherapy \nSelect and explain. \nA. abc, B. abd, C. ac, D. acd', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]