Karl Landsteiner studied blood types in Europe and in the United States in the late nineteenth and early twentieth centuries. Landsteiner won the Nobel Prize in Physiology or Medicine in 1930 for detailing immunological reactions in the ABO blood group system. The ABO blood group system divides human blood into one of four types based on the antibodies that are present on each cell. Landsteiner's work with blood types led physicians to safely perform blood transfusions and organ transplants. Additionally, Landsteiner researched the Rh blood factor, a protein marker on the surface of blood cells and that can impact pregnancy.

Emil von Behring researched treatments for the common childhood disease diphtheria in Germany in the 1890s and early 1900s. Diphtheria is a lethal disease that infected approximately 40,000 people in Germany between 1886 and 1888 with a general mortality rate of twenty-five percent. Behring investigated treatment of diphtheria using serum therapy, which is an alternative to vaccination that uses protective agents from other people’s blood to defend a patient against disease. Behring termed those protective agents antitoxins. He received the first Nobel Prize in Physiology or Medicine for his work on serum therapy, which was one of the first Nobel Prizes given in the field of immunology. Additionally, Behring researched active vaccination as another way to protect patients from diphtheria. Behring’s studies lowered the mortality rate of diphtheria in Germany through serum therapy and vaccination, especially since vaccination confers protection to both mother and infant during pregnancy and after birth.

In 2014, Flor M. Munoz and colleagues published “Safety and Immunogenicity of Tetanus Diphtheria and Acellular Pertussis (Tdap) Immunization During Pregnancy in Mothers and Infants: A Randomized Clinical Trial,” hereafter “Tdap Immunization During Pregnancy,” in the Journal of the American Medical Association. The authors conducted a study to determine how Tdap immunization affected the mother and infant’s immune response to the common childhood diseases tetanus, diphtheria, and pertussis. They found that Tdap immunization did not lead to an increased risk of adverse health events. Furthermore, maternal Tdap immunization provided the infant with protective levels of pertussis antibodies after delivery and did not affect the infant differently from the DTaP vaccination series, which is the version of Tdap for young children. The authors’ findings in “Tdap Immunization During Pregnancy” supported the United States Centers for Disease Control and Prevention’s, or CDC’s, recommendation for pregnant women to receive the Tdap vaccine to prevent disease in mother and infant.