Dr. NK Arora is the chairman of the Covid Working Group of NTAGI, which is an acronym for National Technical Advisory Group on Immunization, to work on introducing new vaccines and strengthening the Universal Immunization Program Works. He said let’s say you want to take another fourth dose. There is a concept called ‘antigen sink’. If a person is immunized repeatedly with a particular type of antigen, the body stops responding or reacts poorly. Why are mRNA vaccines initially given at an interval of six months? Later people are taking it at an interval of three months, but in that case it has not helped much. That’s why there is no justification for taking the fourth dose at the moment. ,