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.
From 2007 to 2010, computer scientist Ross Lazarus and medical doctor Michael Klompas led a study at Harvard Pilgrim Healthcare, Inc. on behalf of the U.S. Department of Health and Human Services (HHS) to identify ways to use Health Information Technology to improve reporting to the Vaccine Adverse Events Reporting System(VAERS). They discovered that 2.6% of all vaccinations led to adverse events. From their review of the literature and their own independent findings, they concluded that VAERS undercounts actual harms from vaccines by a factor of 10 to 100. They built a prototype so that all electronic medical records anywhere in the country could automatically submit a report to VAERS (thus solving the underreporting problem) at which point HHS stopped returning their calls and cut off all contact.
The underreporting problem obviously had not gone away, instead, HHS just decided to cover it up through omission.
In response to the astronomical rates of adverse events following Covid-19 injections, independent researchers have once again attempted to calculate the rate at which harms are underreported to VAERS (referred to as the Under Reporting Factor or URF). Steve Kirsch  and Dr. Jessica Rose  have calculated the URF at 31x to 51x in a number of different ways — basically in the middle of the range originally calculated by Lazarus and Klompas.
Using the newly obtained data from the V-Safe system via an ICAN FOIA , OpenVAERS is able to independently calculate the VAERS URF.
According to V-Safe’s own protocol anyone with a "significant medically attended health event" received a call from VAERS to file a report.
We now have 10,108,273 persons registered with V-Safe. From the ICAN FOIA we know that:
The SPLTTYPE field in VAERS allows us to see which reports have come from V-Safe. This is not a field you can search in Wonder, however you can search it on the OpenVAERS website. And we have a new page that breaks down the V-Safe symptoms and events.
Since 782,913 V-Safe participants required medical care, then 782,913 V-Safe participants should have received a phone call telling them to fill out a VAERS report, and there should be 782,913 reports in VAERS marked ‘vsafe’.
That's not what happened. Instead, there are only 30,492 V-Safe reports in VAERS.
30,492 (actual VAERS reports from v-Safe) / 782,913 (injured people who were instructed to file a report) = 3.89% of the number that should be there. Or, expressed another way, a URF of 26x. And that’s it folks. That is the undercount.
This is the most conservative way to calculate the URF using the new V-Safe numbers. One could also use the 1,344,330 people who missed work or school due to the vaccine or the 1,225,867 people who were unable to conduct normal activities to calculate the URF — in each case one would end up with an even higher URF. Of course, because V-Safe depends on self-reporting through an app, one cannot use it to calculate the URF for vaccine fatalities.1. https://digital.ahrq.gov/sites/default/files/docs/publication/r18hs017045-lazarus-final-report-2011.pdf