<prompt> Vaccine with maximum efficacy isOPVMeaslesBCGTT  <response>: Measles Both measles and tetanus toxoid are highly efficacious vaccines 95 efficacy. But if we compare the doses required and duration of immunity achieved, measles vaccine is clearly ahead of tetanus toxoid. - A single dose of measles vaccine if given at 12 months can achieve 95 efficacy, and if given at 15 months can achieve 98 efficacy. A 2 dose of measles vaccine achieves 99 efficacy. This immunity appears to be of long duration probably for life.-Park 20e p138 - Tetanus toxoid achieves the same efficacy 95 after 3 doses and boosters are required every 5 to 10 yrs to maintain the immunity. Whereas measles requires no boosters BCG and OPV can be easily ruled out. BCG has variable efficacy of 0-80. OPV has 90 efficacy in industrialised countries and 72-98 in hot climates when cold chain is properly maintained. Lower protection against type 3 which can cause rare vaccine associated paralytic polio. Ghai writes-Primary vaccine failure occasionally occurs after three doses of oral polio vaccine. 