The problem with studies that claim to prove there is no harm with multiple vaccines, are that they are studies that are firstly based on ethical restrictions. A test that would conclusively prove the harm of multiple vaccines would require deliberately denying certain children inoculation. Secondly, they monitor only the general population (in preliminary studies they exclude certain risk groups) and in studies after the administration of vaccines usually contribute some of the negative results to other environmental factors.  Studies are therefore in no way conclusive and do not disprove fully the claim that there is no harm connected with multiple vaccines.