Free Vaccinated by Paul A. Offit

closest thing there was to a vaccine, but to me it was just an isolate. He hadn’t made a vaccine.” Even while he was worried about the safety of Enders’s vaccine, Hilleman felt pressured by public health agencies anxious to prevent a disease that was killing thousands of American children every year. He had to find a way to make Enders’s vaccine safer, and he had to do it quickly. The toxic-as-hell problem was solved by Joseph Stokes Jr., the pediatrician who had helped Hilleman test his mumps vaccine.
    Hilleman chose Stokes because he was an expert on gamma globulin, the fraction of blood that contains antibodies. To make gamma globulin, Stokes took blood, let it clot, and stored it in the refrigerator. Eventually, red blood cells formed a clot at the bottom of the tube, and gamma globulin, contained in serum, floated to the top. Stokes knew that people infected with measles, mumps, polio, or hepatitis viruses rarely got the disease again. And he knew that antibodies were the reason why. In the mid-1930s, Stokes showed that gamma globulin taken from polio survivors protected children during polio epidemics. Ten years later, as a special consultant to the surgeon general during the Second World War, Stokes showed that gamma globulin from hepatitis survivors protected American soldiers from hepatitis. For his work on hepatitis, Stokes won the Presidential Medal of Freedom, the nation’s highest civilian award.
    Stokes proposed giving a tiny dose of gamma globulin along with Enders’s measles vaccine, hoping to modify side effects. To see if the idea worked, Stokes and Hilleman went to a women’s prison in central New Jersey.
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    B UILT IN 1913 ON A SPRAWLING FARM IN RURAL H UNTINGTON C OUNTY, Clinton Farms for Women was an ideal prison. An outgrowth of the turn-of-the-century prison reform movement, Clinton provided education, technical training, medical care, and a safe environment for inmates. In the early 1960s, Hilleman and Stokes made several visits to Clinton Farms. (During one early visit, they were eating lunch in the cafeteria when a waitress came to the table and asked them what they wanted to eat. Hilleman needed the prisoners to feel comfortable with his experiment, and he knew that the waitress was also a prisoner. “So what are you in for?” he asked, awkwardly, trying to make conversation. “I killed my parents,” she replied. Seeing the stricken look on his face, she added, “But don’t worry. You’re safe here.” Hilleman never asked that question again and, despite her assurances, never felt completely safe on subsequent visits.)
    Edna Mahan, the prison’s director, revolutionized life at Clinton Farms by taking the locks off doors and prohibiting guards from carrying guns. Prisoners could walk off the grounds any time they wanted. “The prisoners would leave the prison, travel down the road, get into a passing truck, and get themselves pregnant,” recalled Hilleman. “The nursery was full of babies.”
    Stokes and Hilleman injected six infants with Enders’s vaccine in one arm and gamma globulin in the other. None of the infants had a high fever, and only one had a mild rash. Encouraged, they tested hundreds of children. In the end, Stokes’s gamma globulin strategy worked. Subsequent studies during the next few years showed that the percentage of children with rash decreased from 50 percent to 1, and with fever from 85 percent to 5.
    Edna Mahan died in 1968, only a few years after Hilleman performed studies in her prison’s nursery. In a small cemetery on the prison grounds, her elaborate tombstone is surrounded by forty tiny crosses, each representing babies who died in the prison from infections that are now easily prevented by vaccines.
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    T HE SECOND PROBLEM THAT WORRIED H ILLEMAN WAS THAT ENDERS’S vaccine might cause cancer. Although measles virus didn’t cause cancer, Hilleman had reason to be