Pa. Code. § 23.84 (2007)
(a) Medical exemption. Children need not be immunized if a physician or the physician’s designee provides a written statement that immunization may be detrimental to the health of the child. When the physician determines that immunization is no longer detrimental to the health of the child, the child shall be immunized according to this subchapter.
(b) Religious exemption. Children need not be immunized if the parent, guardian or emancipated child objects in writing to the immunization on religious grounds or on the basis of a strong moral or ethical conviction similar to a religious belief.