Yellow fever vaccine-associated neurologic disease (YEL-AND) is a serious but rarely fatal adverse event. It has been reported almost exclusively following primary vaccination. The onset range is 3–28 days following vaccination with the average onset on day 14. Based on a recent analysis of VAERS data, the rate of YEL-AND is approximately 0.8/100,000 doses distributed. Most people with YEL-AND recover completely.
Meningoencephalitis, the most common presentation of YEL-AND, is due to a direct infection of the central nervous system by the vaccine virus. Other manifestations of YEL-AND include Guillain-Barré syndrome and acute disseminated encephalomyelitis. The latter two manifestations are believed to be autoimmune mediated, in which antibodies produced in response to the vaccine cause either peripheral or central demyelination.
Treatment for YEL-AND depends on the particular clinical syndrome. If YEL- AND is suspected in a patient, neurological consultation should be obtained and cerebrospinal fluid (CSF) should be obtained to test for the presence of yellow fever vaccine virus or yellow fever virus-specific antibodies.