Evidence has been presented to support the hypothesis of Meers that the presence of complement-fixing (CF) antibodies to viruses serologically related to yellow fever interfered in a small proportion of persons with antibody response after vaccination with 17D mouse brain yellow fever virus by skin scarification: 96.2% conversion among 157 persons without CF antibodies for related viruses as compared with 84.5% conversion among 129 persons with such antibodies. The data were shown to be statistically significant. No correlation was found between prior infection with Ilesha virus, an arthropodborne virus serologically unrelated to yellow fever, and antibody conversion after 17D yellow fever vaccination.
It was found that some of the persons who failed to convert, on the basis of tests on blood obtained 30 days after vaccination, had demonstrable yellow fever antibody in later blood specimens.
Present address: The University of Kansas Medical Center, Department of Pediatrics, Section of Virus Research, Kansas City 3, Kansas, U.S.A.
Present address: Department of Microbiology, University of Otago, Dunedin, New Zealand.