The document summarizes the Vaccine Adverse Event Reporting System (VAERS), which monitors safety issues with vaccines in the United States. VAERS was established in 1990 to collect reports of adverse events following vaccination. Health care providers are required to report any adverse event listed on the vaccine package insert or in the VAERS Table of Reportable Events. Anyone can submit a report to VAERS of any unwanted side effect following vaccination. While VAERS reports alone cannot prove that a vaccine caused an adverse event, the system serves as an early warning to detect potential safety issues with vaccines.