N.J. Stat. Ann. § 59:6-4

Failure to make physical or mental examination or to make adequate physical or mental examination. Except for an examination or diagnosis for the purpose of treatment, neither a public entity nor a public employee is liable for injury caused by the failure to make a physical or mental examination, or to make an adequate physical or mental examination, of any person for the purpose of determining whether such person has a disease or physical or mental condition that would constitute a hazard to the health or safety of himself or others. For the purposes of this section, "public employee" includes a private physician while actually performing professional services for a public entity as a volunteer without compensation.