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
Vaccine with maximum efficacy is - 
Select and explain. 
A. OPV, B. Measles, C. BCG, D. TT
B: Measles
Answer: B: Measles 
Explanation: Ans. is 'b' i.e. Measles Measles and tetanus have been explained in above explanation. BCG has variable efficiacy of 80% OPV requires multiple doses (three). OPV has > 90% efficacy in industrialized countries and 72-98% in hot climates when cold chain is properly maintained.