Grace Eldering was born in 1900 in Myers, Montana. As a five-year old, she suffered from whooping cough, and she never forgot the endless, painful coughing. In 1927, she graduated from the University of Montana with degrees in biology and chemistry. A year later, she decided to become a bacteriologist. She moved to Michigan on Labor Day in 1928 and volunteered in Lansing in the Department of Health's Bureau of Laboratories. Six months later she was placed on the payroll and was transferred to the lab in Grand Rapids in 1932. Once there, she met Dr. Kendrick, who had established the Grand Rapids lab in 1926. Looking through scientific archives for research possibilities, Eldering and Kendrick found that the cause of whooping cough, pertussis bacillus, had been identified in 1906 but no successful vaccinations had been found.

Doing other lab work during the day, they did much of their whooping cough research at night. They collected live samples of the bacteria from coughing children and grew them on a culture that used sheep's blood. This culture had been identified by their assistant Loney Gordon. Dr. Kenneth Wilcox, an associate of the two doctors, was interviewed by Carolyn Shapiro Shapin. In the interview, he recalled that Eldering and Kendrick inoculated each other with vaccines as a way to test the safety. By 1935, they were successfully vaccinating children. One year later, First Lady Eleanor Roosevelt traveled to Grand Rapids to learn about the vaccination from Eldering and Kendrick. Kendrick said that Eleanor Roosevelt was “the only lay person to really understand what they were doing.” In October 1939, the Michigan Department of Health began manufacturing the vaccine. The two women were modest about their accomplishments and did not look for honors.

Eldering continued her work at the lab. She earned a Ph.D. From John Hopkins University in 1941 and became director of the lab in 1951, after Kendrick retired and left to lecture at the University of Michigan. Wilcox recalls that Eldering managed the lab well, and, as a result, people were loyal to her, showed her respect and enjoyed working there. In 1966, she received the Michigan Public Health Association Distinguished Service Award. Dr. Eldering retired in 1969 but remained active in the community, working with the blind and the West Michigan Environmental Action Council. After they both retired, Eldering and Kendrick shared a house in Grand Rapids. Eldering was inducted into the Michigan Women's Hall of Fame in 1983. She died in 1988 at her home.

Pearl Kendrick was born on August 24, 1890, in Wheaton, Illinois. At the age of three, she suffered from whooping cough. She attended Syracuse University, majoring in zoology and minoring in philosophy. Kendrick told a reporter that philosophy was to help her understand the facts once she learned them. She took a course in parasitology at Columbia. She worked as a high school principal but resigned for an assistant position at the New York State Department of Health laboratories. State of Michigan laboratories director Dr. C.C. Young offered her a job in Lansing.

After doing some work on a test for syphilis, she moved to the Grand Rapids branch in 1926. She became director of the Western Michigan branch. She attended summer classes at the University of Michigan and took a leave of absence to get a Ph.D. in microbiology from John Hopkins University in 1932. During that same year, she began working with Eldering on the whooping cough vaccination, doing much of the research after lab working hours. Kendrick set up a control group that had not be vaccinated to help prove that their vaccination had successfully reduced whooping cough. The state began mass producing the vaccine in 1939 and a few years later the vaccination was made throughout the country. Kendrick was also responsible for combining several agents, diphtheria, pertussis (whooping cough) and tetanus, into one vaccination, the DPT vaccine. Kendrick, like her partner, was modest about their accomplishments and did not look for recognition. Dr. Wilcox recalls Kendrick being the leader of the team and the more dominant one of the two doctors, but, he said, the team worked because Kendrick had “someone who was capable and a well-trained knowledgeable microbiologist in Grace.”

Kendrick was a consultant to the World Health Organization and the United Nations International Children's Emergency Fund, and she helped set up vaccination programs throughout the world. She also spent several months in Mexico City, helping the government to establish an immunization program. She retired from the lab in 1951 and became a lecturer at the University of Michigan. She retired from there in 1960 but continued to remain active. She even traveled to then Soviet Union in 1962 to help Russian experts with developing vaccinations. She died from bone cancer on October 8, 1980, in Grand Rapids. She was inducted into the Michigan Women's Hall of Fame in 1983.

Loney Gordon was born in Arkansas in 1915 and moved to Michigan as a young child. In 1939, she received a bachelor's degree in home economics and chemistry from Michigan State College (now University). As an African-American woman, she had a difficult time finding dietitian jobs. According to a 1999 interview with Gordon by Grand Valley State University history professor Carolyn Shapiro Shapin, Gordon said she found a job working as a dietitian in a mental institution in Virgina but the doctor treated her poorly and she was given inadequate living quarters. To escape this discrimination, she came back to Grand Rapids, where she found that no one would hire her because chefs would not take orders from a black woman. One of Gordon's friends knew Dr. Kendrick and told her that Gordon was looking for a job. Dr. Kendrick hired her in the Michigan Department of Health's Grand Rapids lab around 1944.

In the early 1940s, Gordon tested thousands of culture plates, trying to find the culture that would have sufficient virulence to make the vaccine. Gordon was motivated by the need to help thousands of children who suffered from whooping cough. She discovered that a sheep's blood medium worked best and, in the interview, she said, ”when I found out that was the organism I was just ecstatic. I was crazy with joy and happiness.” Gordon called Kendrick and Eldering wonderful friends who were good to her because she was ambitious. In the interview, she said, “They were like two jewels in a crown for me because they dearly loved me and they gave me access to whatever other organisms that I wanted to study in the lab.”

Gordon worked as a microbiologist and trained scientists and hospital technicians in parasitology and bacteriology. Dr. Kenneth Wilcox, an associate of Gordon's, described Gordon as a woman who always stood her ground and expressed her opinions. After marrying Howard Gordon on June 23, 1956, she moved to the Lansing office of the Department of Heath. After World War II, her scientific work led to her selection for traveling to Europe and the Middle East with the National Council of Christian and Jews to “take the pulse of the people” in the area. She retired from the Michigan Department of Health in 1978. In 1997, the Grand Rapids Public Library had a display on women who made a difference, and it featured Gordon. This display prompted Representative Lynne Martinez of Lansing, who before the display had no idea that Gordon was alive, living in Lansing, and played a role in developing the vaccine, to honor Gordon with a House Resolution. She died in 1999. She was inducted into the Michigan Women's Hall of Fame in 2000.

Katherine Chase was born on October 28, 1909 in Jackson, Michigan. She graduated from the University of Michigan in 1930 with a bachelors of science in bacteriology and received a master's degree in the same subject one year later. In 1934, she was hired at the Grand Rapids branch of the Michigan State Laboratory, where Dr. Kendrick and Dr. Eldering were researching a vaccination for whooping cough. Chase had no direct role in this research, though she did work on identifying the bacteria related to diphtheria, pneumonia and whooping cough. When Dr. Kendrick retired, Dr. Eldering became director of the lab and Chase became the assistant director. Chase retired in 1969.

Before the creation of the vaccine in 1935, whooping cough was killing 6,000 people a year and 95 percent of these deaths were children. It was disease that killed more infants during the 1940s than all of the other childhood diseases combined, including polio. Michigan had a high rate of whooping cough deaths, further prompting Eldering and Kendrick to find a vaccination.

Whooping cough, caused by the bacteria bordetella pertussis, is a highly contagious bacterial infection of the upper respiratory system. Often found in young children, the disease starts similar to a mild respiratory infection, but in a few weeks turns into severe coughing fits. The cough is followed by a whooping sound. Coughing fits can be so severe that they cause vomiting, leading to malnutrition. The coughing fits usually subside after one or two months. Complications with the disease include pneumonia, pulmonary hypertension, and bacterial infections.

Today, it is one of the leading causes of vaccine-preventable deaths world-wide. Ninety percent of all cases occur in third-world countries, where access to the vaccination is not available.