Many take immunization for granted today. It was not very long ago that most children suffered through several mandatory illnesses in their very early years. Some did not make it others were left marked for the rest of their lives. Infants have underdeveloped immune systems for about a month after birth which leaves them open to all kinds of infection. Research has shown that vaccinated mothers pass this immunity to their immune compromised infants. Immunization history shows that this protects them until their systems are ready to start acquiring immunity on their own. An immunized mother makes for a healthier infant.
This so called passive immunity was recognized by Mithradates VI of Pontus who attempted to sure himself up against poison by taking a daily dose of poison that was just less than would kill him. He was trying to build up immunity to it and he was successful. His mixture of universal antidote was used throughout the Renaissance era. Improvements were made over the immunization history years and the new mixture called, Theriacum Andromachi was used into the 1800s. In 1888, the diphtheria toxin was isolated. In 1890, an antitoxin was discovered for diphtheria and tetanus. This led to the first success of the use of a substance intended to create immunity.
As the years passed other diseases were isolated and vaccines created successfully. In 1995, an Ebola outbreak prompted an experiment where the blood of recovering patients was injected into eight other patients in an attempt to prevent or treat the disease. This blood contained Ebola antibodies and only one of the eight patients died in comparison to a usually 80% mortality rate. Immunization history does not include much about how vaccinated mothers can protect their infants. It is a newer research, but one that holds great promise.
Passive immunity that is artificial is accomplished by vaccine. Natural passive immunity describes what a mother passes on to her infant through the placenta during gestation or through breast milk as a neonate. Immunization history of maternal immunization is mostly carried out in areas where there are mothers who have been immunized and others who have not. So that the children studied live under similar conditions. Much of the power behind these studies are for the benefit of countries where immunizations are not standard and the children still suffer from many childhood illnesses that have been eradicated in other places.