From a report published in 2013 through the Institue of Medicine.

"No studies have compared the differences in health outcomes ... between entirely unimmunized populations of children and fully vaccinated children."

"[Furthermore,] studies designed to examine the long-term effects of the cumulative number of vaccines or other aspects of the immunization schedule have not been conducted."

Download the full report here: https://www.nap.edu/catalog/13563/the-childhood-immunization-schedule-and-safety-stakeholder-concerns-scientific-evidence