She may have been vaccinated for travel years before getting pregnant and was good to go. In the 50’s-60’s, I travelled with my parents to many places around the world, including Africa, and had my share of immunizations. At that time there were only a few requirements for just about any place in the world.
She didn’t travel though, the family remained in WA state from 1955 until after her graduation from high school in June 1960, when the family moved to HI. All of her previous travel was within the U.S. For those of us who did travel immunizations were a necessary evil often given too often when encountering different controlling entities which argued their vaccine was stronger than one given previously by another entity! I know that because I had so many needless tetanus shots given that I developed a somewhat severe reaction to tetanus shots!