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: Social & Preventive Medicine
Typhoid revaccination is recommended every ... years in endemic area- 
Select and explain. 
A. 1, B. 3, C. 5, D. 10
B: 3
Answer: B: 3 
Explanation: Ans. is 'b' i.e., 3 o To maintain protection, revaccination is recommended every 3 years.