Maurice Hilleman

Maurice Ralph Hilleman (August 30, 1919 – April 11, 2005) was an American microbiologist whose work in vaccinology led to the creation of more than 40 vaccines—a record no one else has matched. Estimates suggest his vaccines prevent about eight million deaths every year. Many consider him the most influential figure in vaccine history, and he is often called the "father of modern vaccines." Robert Gallo described him as "the most successful vaccinologist in history," and some researchers claim he saved more lives than any other scientist of the 20th century.

Of the 14 vaccines routinely recommended in the United States, Hilleman and his team developed eight: those for measles, mumps, hepatitis A, hepatitis B, chickenpox, *Neisseria meningitidis*, *Streptococcus pneumoniae*, and *Haemophilus influenzae*. During a flu pandemic that began in Southern China, his vaccine is thought to have saved hundreds of thousands of lives. He also helped create the vaccine for the Hong Kong flu and contributed to the discovery of antigenic shift and drift, the cold-causing adenoviruses, the hepatitis viruses, and the potentially cancer-linked SV40 virus.

Hilleman was born on a farm near Miles City, Montana, the eighth child of Anna and Gustav Hillemann. His twin sister died the day they were born, and his mother died two days later. He was raised by his uncle Bob Hilleman and worked on the family farm as a boy. He later credited his success to his early experience with chickens, as fertile chicken eggs had been used since the 1930s to grow viruses for vaccines. His family belonged to the Lutheran Church–Missouri Synod. In eighth grade, he discovered Charles Darwin and was caught reading *On the Origin of Species* in church; he later rejected religion. He nearly missed college due to lack of funds, but his eldest brother stepped in. With family help and scholarships, Hilleman graduated first in his class from Montana State University in 1941. He then won a fellowship to the University of Chicago, earning his doctorate in microbiology in 1944. His thesis focused on chlamydia infections, then thought to be viral; he proved they were caused by the bacterium *Chlamydia trachomatis*, which grows only inside cells.

After joining E.R. Squibb & Sons (now Bristol-Myers Squibb), Hilleman developed a vaccine against Japanese B encephalitis, which threatened U.S. troops in the Pacific during World War II. As chief of the Department of Respiratory Diseases at the Army Medical Center (now Walter Reed Army Institute of Research) from 1948 to 1957, he discovered the genetic changes in the influenza virus known as antigenic shift and drift, theorizing that yearly flu shots would be necessary. In 1957, he moved to Merck & Co. in Rahway, New Jersey, as head of its new virus and cell biology research department in West Point, Pennsylvania. There he developed most of his 40 vaccines, working at the lab bench and providing scientific leadership. He also served on many national and international advisory boards, including the NIH's Office of AIDS Research Program Evaluation and the Advisory Committee on Immunization Practices.

In 1957, Hilleman was among the first to realize that a flu outbreak in Hong Kong could become a massive pandemic. After nine 14-hour days, he and a colleague identified it as a new, deadly strain. Forty million vaccine doses were prepared and distributed. Though 69,000 Americans died, the death toll could have been far higher. He received the Distinguished Service Medal from the U.S. military for his work. His vaccine is believed to have saved hundreds of thousands of lives. During the 1968 Hong Kong flu pandemic, he and his team again played a key role, making nine million doses available in four months.

Hilleman was an early voice warning that simian viruses might contaminate vaccines. The most famous of these is SV40, which contaminated some polio vaccines produced from 1955 to 1963, including both Salk's inactivated and Sabin's oral live vaccines.

In 1963, his daughter Jeryl Lynn came down with the mumps. Hilleman took material from her and used it to create a mumps vaccine. The Jeryl Lynn strain is still used today, including in the trivalent MMR vaccine (measles, mumps, rubella) he also developed—the first approved vaccine combining multiple live virus strains. Like many vaccines of that era, it was tested on children with intellectual disabilities living in group homes, because their crowded conditions put them at higher risk for infectious disease.

Hilleman and his team invented a hepatitis B vaccine by treating blood serum with pepsin, urea, and formaldehyde. Licensed in 1981, it was withdrawn in the United States in 1986 and replaced by a vaccine produced in yeast, which is still in use. By 2003, 150 countries were using it, and the incidence of the disease had dropped dramatically.