Within Primary Sources
What VAERS Can And Cannot Prove
VAERS can help detect possible safety signals, but raw reports cannot prove that a vaccine caused an event.
On this page
- Why VAERS accepts unverified reports
- The difference between signal detection and causation
- How raw report counts become misleading charts
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Introduction
The Vaccine Adverse Event Reporting System (VAERS) is frequently cited in social media posts as proof that vaccines caused large numbers of injuries or deaths. The problem is that VAERS was never designed to prove causation. It is an early-warning reporting system that helps researchers detect possible safety signals that may deserve further investigation. A report in VAERS means that an event happened after vaccination and was reported; it does not mean the vaccine caused the event. Understanding this distinction is a useful exercise in critical thinking because it shows how real public data can be transformed into misleading claims when its purpose and limitations are ignored. [CDC+2vaers.hhs.gov]cdc.govEstablishing a causal relationship requires rigorous…Read more…
Why VAERS Accepts Unverified Reports
VAERS is jointly managed by the U.S. Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). It was created as a broad surveillance system intended to cast a wide net. Anyone can submit a report, including doctors, patients, family members, manufacturers and other observers. In some circumstances, healthcare providers and manufacturers are required to report adverse events even when they are unsure whether a vaccine played any role. [vaers.hhs.gov]vaers.hhs.govVAER SReport an Adverse Event - HHS.govVAERS accepts and analyzes reports of adverse events (AEs) after a person has received a vaccina…
This design is intentional. A system that rejects reports because causation has not yet been established would miss potential warning signs. Instead, VAERS prioritises sensitivity over certainty. Reports can contain incomplete, inaccurate, coincidental or unverified information, but investigators would rather receive too many reports than overlook a genuine safety concern. wonder.cdc.gov+2Bloomberg School of Public Health [wonder.cdc.gov]wonder.cdc.govOpen source on cdc.gov.
A useful analogy is a smoke alarm. A smoke alarm is meant to detect possible danger, not to determine the exact cause of a fire. When the alarm sounds, investigators still need to determine whether there is a real fire, what caused it, and how serious it is. VAERS functions in a similar way as a surveillance tool. [PubMed]pubmed.ncbi.nlm.nih.govSafety monitoring in the Vaccine Adverse Event Reporting…by TT Shimabukuro · 2015 · Cited by 715 — Generally, VAERS data cannot…
The Difference Between Signal Detection and Causation
The most common misunderstanding about VAERS is the assumption that a report equals proof. In reality, health events happen every day in large populations regardless of vaccination status. Heart attacks, strokes, cancers, miscarriages and deaths occur naturally across millions of people. Some of these events will inevitably happen shortly after vaccination simply because of timing. [Every CRS Report]everycrsreport.comSometimes vaccination coincides with a subsequent…Read more…
For this reason, CDC, FDA and VAERS documentation repeatedly state that reports alone cannot establish a causal relationship between a vaccine and an adverse event. Determining causation requires additional evidence, including medical review, epidemiological studies, comparison with background rates, biological plausibility and analysis in other surveillance systems. PubMed+3CDC+3U.S. Food and Drug Administration [cdc.gov]cdc.govEstablishing a causal relationship requires rigorous…Read more…
The distinction can be summarised simply:
QuestionVAERS Can Help Answer?Did an event occur after vaccination?YesIs there an unusual pattern worth investigating?YesDid the vaccine definitely cause the event?NoWhat is the true risk rate?Not by itselfShould further studies be conducted?Yes
Researchers describe VAERS as a “hypothesis-generating” system. Its role is to identify patterns that may indicate a problem, after which more rigorous methods are used to test whether the apparent association is real. [PubMed+2PMC]pubmed.ncbi.nlm.nih.govSafety monitoring in the Vaccine Adverse Event Reporting…by TT Shimabukuro · 2015 · Cited by 715 — Generally, VAERS data cannot…
Importantly, this does not mean VAERS is useless. Some genuine vaccine safety concerns have first appeared as signals in reporting systems. The mistake occurs when people stop at the initial signal and treat it as a confirmed conclusion. [PubMed]pubmed.ncbi.nlm.nih.govSafety monitoring in the Vaccine Adverse Event Reporting…by TT Shimabukuro · 2015 · Cited by 715 — Generally, VAERS data cannot…
How Raw Report Counts Become Misleading Charts
A common social-media tactic is to present a chart showing thousands of VAERS reports and then imply that every report represents a confirmed vaccine injury or death. This interpretation ignores how the database works. Official VAERS documentation explicitly warns that report totals alone cannot be used as evidence that a vaccine caused an event, nor as evidence of the frequency or severity of vaccine-related problems. [vaers.hhs.gov]vaers.hhs.govVAER SData - HHS.gov8 May 2025 — The number of reports alone cannot be interpreted as evidence of a causal association between a vaccin…
Several factors can distort raw counts:
- Coincidental events: Some reports describe health events that happened after vaccination but were unrelated to it. [U.S. Food and Drug Administration]fda.govvaccine adverse event reporting system vaers questions and answersFood and Drug AdministrationVaccine Adverse Event Reporting System (VAERS)…4 Oct 2024 — No. VAERS reports generally cannot be used to…
- Stimulated reporting: Media attention can dramatically increase reporting volumes without changing the actual risk. [wonder.cdc.gov]wonder.cdc.govAs a result, there are limitations on how the data can be used scientifically. Data from VAERS reports…Read more…
- Duplicate or incomplete reports: Multiple submissions may describe the same event, and some reports contain missing information. [wonder.cdc.gov]wonder.cdc.govOpen source on cdc.gov.
- Lack of denominator data: A count of reports means little without knowing how many vaccine doses were administered. [wonder.cdc.gov]wonder.cdc.govOpen source on cdc.gov.
During the COVID-19 vaccination campaign, billions of doses were administered globally and hundreds of millions in the United States. A large vaccination programme naturally generates many reports because millions of people are being monitored. Looking only at the number of reports while ignoring the size of the vaccinated population creates a misleading picture of risk. [U.S. Food and Drug Administration]fda.govcovid 19 vaccine safety surveillanceFood and Drug AdministrationCOVID-19 Vaccine Safety Surveillance10 Jan 2025 — Some VAERS reports might represent true vaccine reactions o…
A Typical False Causation Claim
A recurring online claim states that VAERS contains a certain number of death reports and therefore proves vaccines killed that many people. This reasoning confuses temporal association with causation.
VAERS accepts reports of deaths occurring after vaccination because investigators need to know about them. Reporting requirements may encourage submission even when no causal link is suspected. The presence of a death report therefore indicates that a death occurred after vaccination and was reported to the system; it does not establish that the vaccine caused the death. [Nebraska Medicine]nebraskamed.comdoes vaers list deaths caused by covid 19 vaccinesreport to VAERS the following adverse events after COVID-19…
Official guidance repeatedly warns against making this leap. FDA, CDC and VAERS documentation all state that reports alone cannot determine whether a vaccine caused a reported outcome. Further investigation is required before any causal conclusion can be reached. U.S. Food and Drug Administration+2CDC [fda.gov]fda.govvaccine adverse event reporting system vaers questions and answersFood and Drug AdministrationVaccine Adverse Event Reporting System (VAERS)…4 Oct 2024 — No. VAERS reports generally cannot be used to…
Fact-checking organisations have repeatedly documented cases where social-media users treated VAERS reports as confirmed injuries or deaths despite explicit warnings attached to the database itself. [FactCheck.org]factcheck.orgPosts Falsely Claim CDC Official Admitted COVID-19…20 Feb 2023 — Health problems that are reported to the Vaccine Adverse Event Report…
What Critical Readers Should Check
When a post cites VAERS as proof that vaccines caused a particular outcome, several questions help separate evidence from interpretation:
- Is the post discussing reports or confirmed causal findings?
- Does it acknowledge that anyone can submit reports?
- Does it distinguish signal detection from proof?
- Does it provide population-level context and background rates?
- Does it cite follow-up investigations rather than only raw report counts?
If the answer to most of these questions is no, the claim is probably overstating what the data can support.
Why This Matters Beyond Vaccines
VAERS illustrates a broader lesson about public datasets in the age of social media and AI. A dataset can be authentic, transparent and valuable while still being easy to misuse. The fact that data are real does not mean every interpretation is valid. Critical thinking requires understanding what a dataset was designed to measure, how information enters the system, and what conclusions its creators explicitly say should not be drawn from it. VAERS remains an important vaccine-safety tool precisely because it is designed to generate questions. Problems arise when those questions are presented as settled answers. vaers.hhs.gov+3CDC+3vaers.hhs.gov [cdc.gov]cdc.govEstablishing a causal relationship requires rigorous…Read more…
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Endnotes
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Source: cdc.gov
Link: https://www.cdc.gov/vaccine-safety-systems/vaers/index.htmlSource snippet
Establishing a causal relationship requires rigorous...Read more...
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Source: vaers.hhs.gov
Title: VAER S
Link: https://vaers.hhs.gov/data.htmlSource snippet
Data - HHS.gov8 May 2025 — The number of reports alone cannot be interpreted as evidence of a causal association between a vaccin...
Published: May 2025
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Source: fda.gov
Title: vaccine adverse event reporting system vaers questions and answers
Link: https://www.fda.gov/vaccines-blood-biologics/vaccine-adverse-events/vaccine-adverse-event-reporting-system-vaers-questions-and-answersSource snippet
Food and Drug AdministrationVaccine Adverse Event Reporting System (VAERS)...4 Oct 2024 — No. VAERS reports generally cannot be used to...
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Source: vaers.hhs.gov
Title: VAER S
Link: https://vaers.hhs.gov/reportevent.htmlSource snippet
Report an Adverse Event - HHS.govVAERS accepts and analyzes reports of adverse events (AEs) after a person has received a vaccina...
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Source: wonder.cdc.gov
Link: https://wonder.cdc.gov/wonder/help/vaers.html -
Source: vaers.hhs.gov
Title: VAER S
Link: https://vaers.hhs.gov/faq.htmlSource snippet
FAQs - HHS.govOne of the main limitations of VAERS data is that it cannot determine if the vaccine caused the reported adverse ev...
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Source: pmc.ncbi.nlm.nih.gov
Title: Generally, VAERS data cannot be used to determine if a vaccine caused an advers
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC4632204/Source snippet
Safety monitoring in the Vaccine Adverse Event Reporting...by TT Shimabukuro · 2015 · Cited by 692 — Generally, VAERS data cannot be...
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Source: pmc.ncbi.nlm.nih.gov
Title: VAERS does
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC6500450/Source snippet
Reports to the Vaccine Adverse Event Reporting System...by LM Pedro · 2013 · Cited by 71 — VAERS is not designed to assess causal ass...
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Source: fda.gov
Title: covid 19 vaccine safety surveillance
Link: https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/covid-19-vaccine-safety-surveillanceSource snippet
Food and Drug AdministrationCOVID-19 Vaccine Safety Surveillance10 Jan 2025 — Some VAERS reports might represent true vaccine reactions o...
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Source: wonder.cdc.gov
Link: https://wonder.cdc.gov/vaers.htmlSource snippet
As a result, there are limitations on how the data can be used scientifically. Data from VAERS reports...Read more...
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC4333877/Source snippet
by C Tao · 2014 · Cited by 3 — Symptoms reported occurring after vaccination do not necessarily have a causality association with the...
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Source: factcheck.org
Link: https://www.factcheck.org/2023/02/scicheck-posts-falsely-claim-cdc-official-admitted-covid-19-vaccines-cause-debilitating-illnesses/Source snippet
Posts Falsely Claim CDC Official Admitted COVID-19...20 Feb 2023 — Health problems that are reported to the Vaccine Adverse Event Report...
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Source: cdc.com
Link: https://cdc.com/Source snippet
CDC Data CentresCDC provides state-of-the-art, sovereign and highly secure, large-scale hosting facilities to the public and private sect...
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Source: publichealth.jhu.edu
Title: what vaers is and isnt
Link: https://publichealth.jhu.edu/2022/what-vaers-is-and-isntSource snippet
VAERS Is (And Isn't) | Johns Hopkins3 May 2022 — Moreover, the CDC and FDA do not restrict what people can report, as long as it happened...
Published: May 2022
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Source: pubmed.ncbi.nlm.nih.gov
Link: https://pubmed.ncbi.nlm.nih.gov/26209838/Source snippet
Safety monitoring in the Vaccine Adverse Event Reporting...by TT Shimabukuro · 2015 · Cited by 715 — Generally, VAERS data cannot...
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Source: everycrsreport.com
Link: https://www.everycrsreport.com/reports/IN12486.htmlSource snippet
Sometimes vaccination coincides with a subsequent...Read more...
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Source: nebraskamed.com
Title: does vaers list deaths caused by covid 19 vaccines
Link: https://www.nebraskamed.com/COVID/does-vaers-list-deaths-caused-by-covid-19-vaccinesSource snippet
report to VAERS the following adverse events after COVID-19...
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11252891/Source snippet
by ER Miller · 2020 · Cited by 55 — Underreporting is a limitation common to passive surveillance systems, including the Vaccine Adver...
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC10872386/Source snippet
adverse events and associations post COVID-19...by Y Li · 2023 · Cited by 15 — This study analyzed the Vaccine Adverse Event Reporting S...
Additional References
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Source: science.org
Title: antivaccine activists use government database side effects scare public
Link: https://www.science.org/content/article/antivaccine-activists-use-government-database-side-effects-scare-publicSource snippet
Antivaccine activists use a government database on side...26 May 2021 — To counter misinterpretation of its data, the VAERS website prom...
Published: May 2021
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Source: adultvaccinesnow.org
Link: https://adultvaccinesnow.org/resources/cdc-releases-data-showing-safety-of-covid-vaccines/Source snippet
CDC Releases Data Showing Safety of COVID VaccinesVAERS is an existing national passive surveillance system for adverse events after vacc...
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Source: webmd.com
Link: https://www.webmd.com/vaccines/vaers-and-vaccine-safetySource snippet
VAERS and Vaccine Safety: What You Need to KnowVAERS doesn't determine whether a vaccine caused or played a role in a particular health i...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/232249468_Causality_assessment_of_adverse_events_reported_to_the_Vaccine_Adverse_Event_Reporting_System_VAERSSource snippet
We have outlined the limitations of using VAERS data for causal. assessments, yet we support the need for...Read more...
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Source: facebook.com
Link: https://www.facebook.com/DurhamHealthNC/posts/if-vaccines-are-safe-why-are-there-harmful-effects-reported-in-vaers-its-importa/1162242512582508/Source snippet
VAERS data alone cannot determine if the reported adverse event was caused by a COVID-19 vaccination. Anyone can report events to VAERS...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/280387564_Safety_monitoring_in_the_Vaccine_Adverse_Event_Reporting_System_VAERSSource snippet
Safety monitoring in the Vaccine Adverse Event Reporting...Generally, VAERS data cannot be used to determine if a vaccine caused an adve...
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Source: facebook.com
Link: https://www.facebook.com/SCEMD/posts/did-you-know-vaers-data-alone-cannot-show-that-an-adverse-event-following-covid-/394741205354542/Source snippet
f a vaccine is linked to an adverse event. Reports may...Read more...
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Source: bmjgroup.com
Link: https://bmjgroup.com/is-the-us-reporting-system-for-vaccine-safety-broken/Source snippet
pposed to be user-friendly, responsive, and transparent.Read more...
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Source: kcra.com
Title: As we said, everyone is encouraged
Link: https://www.kcra.com/article/fact-check-viral-posts-misuse-vaers-data-to-make-false-claims-about-covid-19-vaccines/36068010Source snippet
Fact Check: Viral posts misuse VAERS data to make false...31 Mar 2021 — “The biggest limitation is it usually cannot help us assess caus...
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Source: disclaimer.pervaers.com
Link: https://disclaimer.pervaers.com/Source snippet
perVAERSThe number of reports alone cannot be interpreted as evidence of a causal association between a vaccine and an adver...
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