What is the efficacy of typhoid vaccines?
The clinical efficacy of all the typhoid vaccines is similar. It is 70 – 90 % with most of the vaccines. The phenol killed whole cell typhoid vaccine though is not as good as other 3 vaccines i.e. acetone killed vaccine, Vi antigen vaccine or the ty21a oral vaccine. The immunity lasts for 3-5 years as discussed before. The liquid form of ty21a vaccine in sachet form has efficacy as high as 90% in some studies. But it is not available at present. 4 capsule schedule of ty21a vaccine leads to 4-5 years protection as compared to 3-4 years with 3 capsule schedule.
