This question is very frequently asked by the parents. The best approach will be to get blood tested for widal
. Two types of antigens are involved in this test: Salmonella typhi
'O' and 'H'. The former is elevated beyond 1: 160, if the child has acute typhoid fever
. The latter is elevated following Typhoid vaccination
or due to an earlier typhoid infection in the past. So if your child has a significantly elevated 'H' level beyond 1:160 , he or she might have received Typhoid vaccination and there is no need to repeat it earlier than next two years. You can consult your child specialist to guide you about the interpretation of the test results.
In case you don't want to have this test done ,then repeating the vaccination is not harmful.
Good luck to you and your child.