William Pollack, a medical researcher who helped develop a vaccine that virtually eradicated a disease once responsible for 10,000 infant deaths a year in the United States, died on Nov. 3 in Yorba Linda, Calif. He was 87.

He had diabetes and heart disease, his son Malcolm said in confirming the death.

Dr. Pollack was a senior scientist in the research laboratory of Ortho Pharmaceutical Company in Raritan, N.J., in the early 1960s when he began a collaboration with two Columbia University researchers, Dr. Vincent J. Freda and Dr. John G. Gorman, to conceive a novel treatment for erythroblastosis fetalis, a blood disorder commonly called Rh disease. The ailment is caused by seemingly superficial differences in the blood types of pregnant women and their fetuses.

Besides the biochemical traits that define the major blood types — A, B, AB and O — the blood of 85 percent of people carries a cluster of surface proteins known as the Rh factor, named for the rhesus monkeys in which it was first identified in 1940. Blood transfusions between people who have the Rh factor (known as Rh positive) and people who do not (Rh negative) cause severe immune reactions.

Rh disease occurs when a pregnant woman is Rh negative and her fetus is Rh positive. In the mixing of blood between the two during pregnancy, the mother’s Rh-negative blood cells produce antibodies that attack the blood cells of the fetus. Depending on the strength of the mother’s immune response, the effects on the baby can range from mild anemia to stillbirth.