This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'Pneumococcal vaccine is prepared from \nSelect and explain. \nA. Cell surface antigen, B. Capsular polysaccharide, C. exotoxin, D. M protein', 'role': 'user'}, {'content': "Answer: B \nExplanation: Pneumococcal vaccine: A polyvalent polysaccharide vaccine representing the capsular antigens of the 23 most prevalent serotypes have been stated to give 80-90% protection. Given in patients with enhanced risk of pneumococcal infection, absent or dysfunctional spleen, sickle cell disease, immunodeficiency etc. It is not recommended in children under the age of two years and those with lymphoreticular malignancies and immunosuppressive therapy A 7 valent conjugate vaccine (conjugated to the CRM197 protein of C.diptheriae) is now available which can be used in children from two months to two years. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 228", 'role': 'assistant'}]