Paediatrician Indirapuram. What are vaccines And why do I need to vaccinate my child? Vaccines are probably the most useful and cost effective public health tools known to mankind for preventing diseases. Investing money in vaccination is much wiser decision than spending money on readymade baby foods. Once a child suffers from infection patents nor have to spend a huge amount in treatment, there is also loss on a number of school days, abstinence in work by parents and other social issues.