Please answer a question about the following article about Pharmaceutical industry:

Other notable new vaccines of the period include those for measles (1962, John Franklin Enders of Children's Medical Center Boston, later refined by Maurice Hilleman at Merck), Rubella (1969, Hilleman, Merck) and mumps (1967, Hilleman, Merck) The United States incidences of rubella, congenital rubella syndrome, measles, and mumps all fell by >95% in the immediate aftermath of widespread vaccination. The first 20 years of licensed measles vaccination in the U.S. prevented an estimated 52 million cases of the disease, 17,400 cases of mental retardation, and 5,200 deaths.

Who helped refine the measles vaccine?
Maurice Hilleman