By Matthew HerperAug. 11, 2026
Senior Writer, Medicine, Editorial Director of Events
History tells us that President Trump’s executive order calling for the measles, mumps, and rubella vaccine to be split into separate shots could do real harm. If policymakers prevail on vaccine makers, it will mean more missed vaccine doses, and more sick kids. But first a lesson on where the shot comes from.
In March 1963, a 5-year-old girl named Jeryl Lynn woke up with a sore throat at 1 a.m. Her father, a six-foot-one widower who had lost his wife to breast cancer four months earlier, bent down and felt the lumps on her neck. He was a scientist at the pharmaceutical company Merck, and he checked “The Merck Manual,” a medical reference book. “Oh my God,” he said. “You’ve got the mumps.”
The father put his daughter to bed and told his housekeeper he would be gone for a while. He went to the office, rummaged through some drawers, and found cotton swabs and a vial of nutrient broth. He woke Jeri, swabbed her throat, and comforted her. Then he went back to work again, using that virus to infect incubating chicken eggs and then move the virus into culture dishes of chick cells. As it became adapted to chickens it became worse at infecting humans — and became a vaccine.
