In 1935 Eddy transferred to the National Institutes of Health in Bethesda, Maryland, where she joined the Biologics Control Division, the department responsible for checking the quality of vaccines distributed by the Federal government of the United States.
[5] During World War II, Eddy was made responsible for checking the quality of influenza vaccines used by the United States Army.
As part of the Biologics Control Division, Eddy and her team created the first reliable potency test for flu vaccines so that the quality and effectiveness would be consistent throughout manufacturing.
[5] In 1954, the National Institutes of Health delegated Eddy to perform safety tests for a batch of inactivated polio vaccines developed by Jonas Salk for Cutter Laboratories.
[12][10] On April 29, 1955 William Sebrell, the director of the National Institutes of Health, chaired a meeting to examine Cutter's manufacturing protocols.
The Cutter incident was one of the worst pharmaceutical disasters in US history, and exposed several thousand children to live polio virus on vaccination.
[9][13] After the Cutter incident in 1954, Eddy had been sidelined for whistleblowing about the presence of live virus in Jonas Salk's inactivated polio vaccine.
She was later on approached by Sarah Elizabeth Stewart, her colleague at the National Institutes of Health, in 1956 while both were working on testing common cold vaccines.
[1] The results of their collaboration earned them recognition by Time magazine in 1959, featuring a cover story on newly discovered viral agents that cause cancer.
[1] Ludwik Gross and Sarah Stewart had been researching cancer-causing viruses concurrently and separately, and had been aware of each other's work since at least December 1952.
When the virus was renamed "SE polyomavirus" for Stewart and Eddy, Gross felt that this diminished his role in the discovery, and he wrote several letters to his peers arguing his point.
"[18] In 1959, Eddy began to conduct safety studies on polio vaccines, which used viruses grown in monkey kidney cells.
[5] In 1961, Eddy showed that an extract of rhesus monkey kidney cells used in the creation of the polio vaccine caused tumors in newborn hamsters.
Given the preponderance of evidence, this paper drew the conclusion that the oncological agent in the rhesus monkey kidney cell extracts were identical to the SV40 virus.
[2][20] Eddy suggested that this contamination could be avoided in the future by screening cultures of C. aethiops kidney cells for the characteristic cytopathic (cellular) changes that SV40 causes.
[21] Theoretically speaking, it added to a growing body of evidence that the monkey, like the mouse, could harbor oncogenic (cancer-causing) viruses that could affect other animal species.
[23] In 1937, Eddy and her colleagues studied multiple aspects of Mycobacterium leprae, the bacteria that causes leprosy, to gain valuable information for future diagnostic purposes.
Upon retirement she received several awards, including a Special Citation from the secretary of the Department of Health, Education, and Welfare (HEW).
[3] Eddy received an honorary Doctor of Science degree from Marietta College in 1955, and the United States Department of Health, Education and Welfare awarded her a Superior Service Medal in 1967.