One of the most commonly repeated phrases we hear regarding vaccines is that “vaccine injury/adverse events are extremely rare.”

So would it surprise you to learn that research funded by the CDC showed that adverse vaccine reactions are only reported less than 1% of the time they’re occurring?

From December of 2007 to September 2009, the CDC funded a million dollar research project with Harvard Pilgrim Healthcare(HPH) to assess VAERS reporting. The research project was funded specifically to “improve the quality of vaccination programs by improving the quality of physician adverse vaccine event detection and reporting to the national Vaccine Adverse Event Reporting System (VAERS)”.

The project ended September 29, 2010 when according to HPH, “Restructuring at CDC and consequent delays in terms of decision making have made it challenging despite best efforts to move forward”.

This came after preliminary reports had been submit indicating that “Fewer than 1% of vaccine adverse events are reported. Low reporting rates preclude or slow the identification of “problem” vaccines that endanger public health.”


The researchers recommended that new surveillance methods be implemented and barriers such as lack of clinician awareness and uncertainty of what and how to report be addressed.

The report concludes stating, “there was never an opportunity to perform system performance assessments because the necessary CDC contacts were no longer available and the CDC consultants responsible for receiving data were no longer responsive to our multiple requests to proceed with testing and evaluation.”

Less than 1% of adverse vaccine reactions are reported.

Less than 1%