VAERS accepts reports of adverse events and reactions that occur following vaccination. Healthcare providers, vaccine manufacturers, and the public can submit reports to the system. While very important in monitoring vaccine safety, VAERS reports alone cannot be used to determine if a vaccine caused or contributed to an adverse event or illness. The reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable. In large part, reports to VAERS are voluntary, which means they are subject to biases. This creates specific limitations on how the data can be used scientifically. Data from VAERS reports should always be interpreted with these limitations in mind.
The strengths of VAERS are that it is national in scope and can quickly provide an early warning of a safety problem with a vaccine. As part of CDC and FDA’s multi-system approach to post-licensure vaccine safety monitoring, VAERS is designed to rapidly detect unusual or unexpected patterns of adverse events, also known as “safety signals.” If a safety signal is found in VAERS, further studies can be done in safety systems such as the CDC’s Vaccine Safety Datalink (VSD) or the Clinical Immunization Safety Assessment (CISA) project. These systems do not have the same scientific limitations as VAERS, and can better assess health risks and possible connections between adverse events and a vaccine.
Key considerations and limitations of VAERS data:
VAERS data available to the public include only the initial report data to VAERS. Updated data which contains data from medical records and corrections reported during follow up are used by the government for analysis. However, for numerous reasons including data consistency, these amended data are not available to the public.
VAERS is widely acknowledged, even by the CDC, to be vastly underreported. From their Dataguide:
"'Underreporting' is one of the main limitations of passive surveillance systems, including VAERS. The term, underreporting, refers to the fact that VAERS receives reports for only a small fraction of actual adverse events. The degree of underreporting varies widely."
The Lazarus report from Harvard Pilgrim Health Care in 2009 used Epic (one of the largest electronic medical records systems used in the US) to gather data automatically from the system.
“Every patient receiving a vaccine was automatically identified, and for the next 30 days, their health care diagnostic codes, laboratory tests, and medication prescriptions are evaluated for values suggestive of an adverse vaccine event. When a possible adverse event was detected, it was recorded, and the appropriate clinician was to be notified electronically.”
The researchers attempted to make filing a report easier as well. "Clinicians' in-basket messaging was designed to provide a preview of a pre-populated report with information from the electronic health records about the patient, including vaccine type, lot number, and possible adverse effect, to inform their clinical judgment regarding whether they wish to send a report to VAERS. Clinicians would then have the option of adding free-text comments to pre-populated VAERS reports or to document their decision not to send a report."
The results of the report state, "Preliminary data were collected from June 2006 through October 2009 on 715,000 patients, and 1.4 million doses (of 45 different vaccines) that were given to 376,452 individuals. Of these doses, 35,570 possible reactions (2.6 percent of vaccinations) were identified."
Further it states, "Adverse events from drugs and vaccines are common, but underreported. Although 25% of ambulatory patients experience an adverse drug event, less than 0.3% of all adverse drug events and 1-13% of serious events are reported to the Food and Drug Administration (FDA). Likewise, fewer than 1% of vaccine adverse events are reported."
The results clearly showed that injury was much more common than the one-in-a-million lie that is often cited.
More recently Steve Kirsch and Dr. Jessica Rose have both calculated an Under Reporting Factor (URF) for Covid vaccine injuries. Steve used multiple methods to confirm a URF of approximately 41. Dr. Rose used of the current Department of Defense Medical Epidemiology Database (DMED) miscarriage rates to calculate a URF of 49.