Zerwas was appointed executive vice chancellor for health affairs for the University of Texas System and assumed office on October 1, 2019.

After graduating from the University of Houston, Zerwas earned his medical degree at Baylor College of Medicine in 1980 and started a full-time practice in 1985.

He worked with the Boy Scouts of America to establish a troop in the Pecan Grove area, serving as cub master and den leader for several years.

John and his wife Sylvia Haist married in December 2015 and reside in Richmond; they together have six children and seven grandchildren: Isabella, Matthew, Dashel, Oliver, Beatrice, Tinley, and Harlow.

Zerwas practices anesthesiology with US Anesthesia Partners (USAP), a group he co-founded and in which he remains active in the operations of the partnership.