Adverse event reports following Japanese encephalitis vaccination in the United States, 1999–2009

We reviewed adverse events following receipt of inactivated mouse brain-derived Japanese encephalitis (JE) vaccine reported to the U.S. Vaccine Adverse Event Reporting System (VAERS) from 1999 to 2009. During this period, VAERS received 300 adverse event reports following JE vaccination (24 per 100,000 doses distributed); 106 (35%) were classified as hypersensitivity reactions (8.4 per 100,000 doses) and four (1%) were classified as neurologic events (0.3 per 100,000 doses). Twenty-three (8%) reports described serious adverse events (1.8 per 100,000 doses distributed). There were no reports of encephalitis, meningitis, or Guillain-Barré syndrome. As reported previously, hypersensitivity reactions were common among persons receiving inactivated mouse brain-derived JE vaccine.