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

Area of Science:

• Vaccinology
• Immunology
• Public Health

Background:

• The inactivated mouse brain-derived Japanese encephalitis (JE) vaccine has been used to prevent JE virus infection.
• Understanding the safety profile of vaccines is crucial for public health initiatives.

Purpose of the Study:

• To analyze adverse events reported following the administration of the inactivated mouse brain-derived JE vaccine.
• To assess the frequency and types of adverse events, including serious events and specific neurological conditions.

Main Methods:

• A retrospective review of adverse event reports submitted to the U.S. Vaccine Adverse Event Reporting System (VAERS).
• Data collected from 1999 to 2009, focusing on reports associated with JE vaccination.
• Categorization of adverse events into hypersensitivity reactions, neurologic events, and serious adverse events.

Main Results:

• 300 adverse event reports were received following JE vaccination, with a rate of 24 per 100,000 doses.
• Hypersensitivity reactions constituted 35% of reports (8.4 per 100,000 doses).
• Four neurologic events (0.3 per 100,000 doses) and 23 serious adverse events (1.8 per 100,000 doses) were reported. No cases of encephalitis, meningitis, or Guillain-Barré syndrome were documented.

Conclusions:

• Hypersensitivity reactions are a common adverse event associated with the inactivated mouse brain-derived JE vaccine.
• The vaccine demonstrates a favorable safety profile regarding serious neurologic events.
• Continued surveillance through systems like VAERS is important for monitoring vaccine safety.