We were able to locate this image of Jonas Salk. The client originally requesting it had found it on Wikipedia, regrettably marked as being in the public domain. Wikipedia decided to take the image down even though I would have liked them to just make sure it was properly attributed and keep it on the Jonas Salk page. One of Dr. Salk's sons got in touch; also a doctor, even he felt the injection shot was a little discomfiting.

Dr. Jonas Salk, 1956 © Yousuf Karsh