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Data source: VAERS (Vaccine Adverse Event Reporting System)

Data through 2026 · Updated quarterly

Built by TheDataProject.ai · © 2026 VaccineWatch

Important: VAERS accepts reports of adverse events following vaccination. For any given report, there is no certainty that the reported event was caused by the vaccine. Reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable. Most reports to VAERS are voluntary, which means they are subject to biases. This data cannot be used to determine if vaccines cause or contribute to adverse events.

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Important: VAERS reports alone cannot determine if a vaccine caused an adverse event. Reports may contain incomplete, inaccurate, or unverified information. Correlation does not equal causation.

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  3. Most Reported Symptoms
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Most Reported Symptoms

The 20 most commonly reported adverse symptoms in VAERS. Most of the top symptoms are expected immune responses — fever, headache, pain at the injection site.

276,779
reports for Pyrexia — the most commonly reported symptom, representing a normal immune response to vaccination

What the Top Symptoms Tell Us

The most reported symptoms in VAERS are largely what you'd expect from normal immune responses:

  • Pyrexia (fever): The #1 reported symptom. Fever is a sign the immune system is responding to the vaccine — exactly what it's supposed to do.
  • Headache, fatigue, pain: Common side effects of almost all vaccines, usually resolving within 1-3 days.
  • Injection site reactions: Redness, swelling, and pain at the injection site are among the most common and expected side effects.

The prevalence of mild, expected symptoms at the top of the list actually provides reassurance: it shows that VAERS is capturing the full spectrum of post-vaccination experiences, not just serious events.

Severity Breakdown

While most top symptoms are mild, some have significant hospitalization rates. This reflects that even common symptoms can sometimes be severe enough to require medical attention, particularly in vulnerable populations.

Top 20 Symptoms

#SymptomReportsDeathsHosp.Severity
1Pyrexia276,7792,36123,8918.6%
2Headache228,03881511,1954.9%
3Pain199,8918059,3314.7%
4Fatigue181,3551,33610,5405.8%
5Chills156,1396506,6844.3%
6Pain in extremity143,9253845,4293.8%
7No adverse event142,25623390.0%
8Nausea135,8769649,0426.7%
9Injection site pain134,2941252,2351.7%
10Dizziness133,3234637,3035.5%
11Injection site erythema131,718341,7711.3%
12Rash113,6132214,3323.8%
13COVID-1997,6237,31635,29536.2%
14Injection site swelling96,522281,4071.5%
15Myalgia95,2022584,0114.2%
16Erythema90,703742,1752.4%
17Pruritus88,832361,4751.7%
18Arthralgia87,1711913,8064.4%
19Dyspnoea85,9764,20322,74926.5%
20Vomiting79,5471,34311,54414.5%

Key Takeaways

  • 1.The most commonly reported symptoms are expected immune responses (fever, headache, pain)
  • 2.A single VAERS report typically lists multiple symptoms, so symptom counts exceed report counts
  • 3.The dominance of mild symptoms at the top confirms VAERS captures the full spectrum of experiences

2026 Data Context

As VAERS reporting normalizes following the COVID-19 pandemic surge, the data landscape for commonly reported symptoms is shifting. Annual VAERS reports in 2025-2026 have returned to the 35,000-45,000 range typical of the pre-pandemic era (2015-2019), making year-over-year comparisons more meaningful again.

The HHS administration has signaled increased focus on vaccine safety data analysis, including the development of AI-powered tools for pattern detection in VAERS reports. While these tools are still under development, they represent a potential evolution in how adverse event data is analyzed and interpreted.

New vaccines entering the market — including RSV vaccines for older adults and pregnant women, updated COVID-19 formulations, and potential H5N1 avian flu vaccines — continue to add new data streams to VAERS. Each new vaccine type provides additional context for understanding commonly reported symptoms across the full spectrum of vaccine safety surveillance.

Limitations of This Analysis

This analysis is based entirely on VAERS passive surveillance data, which carries important limitations that must be understood:

  • Underreporting: Studies estimate that only 1-10% of adverse events are reported to VAERS. This means the true number of events is likely much higher than what appears in the data.
  • Stimulated reporting: Media coverage and public awareness can temporarily increase reporting rates for specific vaccines, independent of any change in actual safety.
  • No control group: VAERS does not include a comparison group of unvaccinated individuals, making it impossible to determine whether reported events occurred at a higher rate than expected.
  • Variable data quality: VAERS reports range from detailed medical records submitted by healthcare providers to brief descriptions from patients. Not all reports are verified for medical accuracy.
  • Duplicate reports: The same event may be reported by multiple people (patient, doctor, manufacturer), and some duplicates may remain in the data.

For these reasons, VAERS data is best used for signal detection — identifying potential safety concerns that warrant further investigation — rather than for definitive risk assessment. When VAERS surfaces a potential signal, it is investigated using more rigorous systems like the Vaccine Safety Datalink (VSD) and controlled epidemiological studies.

About This Data

All data on VaccineWatch comes from the official VAERS public-use datasets published by the CDC and FDA. Our current dataset covers reports from 1990 through early 2026. We process the raw data without filtering or editorializing — every metric is a transparent aggregation of official government data.

Our Methodology →FAQ →Disclaimer →

2026 Data Context

As VAERS reporting normalizes following the COVID-19 pandemic surge, the data landscape for commonly reported symptoms is shifting. Annual VAERS reports in 2025-2026 have returned to the 35,000-45,000 range typical of the pre-pandemic era (2015-2019), making year-over-year comparisons more meaningful again.

The HHS administration has signaled increased focus on vaccine safety data analysis, including the development of AI-powered tools for pattern detection in VAERS reports. While these tools are still under development, they represent a potential evolution in how adverse event data is analyzed and interpreted.

New vaccines entering the market — including RSV vaccines for older adults and pregnant women, updated COVID-19 formulations, and potential H5N1 avian flu vaccines — continue to add new data streams to VAERS. Each new vaccine type provides additional context for understanding commonly reported symptoms across the full spectrum of vaccine safety surveillance.

Limitations of This Analysis

This analysis is based entirely on VAERS passive surveillance data, which carries important limitations that must be understood:

  • Underreporting: Studies estimate that only 1-10% of adverse events are reported to VAERS. This means the true number of events is likely much higher than what appears in the data.
  • Stimulated reporting: Media coverage and public awareness can temporarily increase reporting rates for specific vaccines, independent of any change in actual safety.
  • No control group: VAERS does not include a comparison group of unvaccinated individuals, making it impossible to determine whether reported events occurred at a higher rate than expected.
  • Variable data quality: VAERS reports range from detailed medical records submitted by healthcare providers to brief descriptions from patients. Not all reports are verified for medical accuracy.
  • Duplicate reports: The same event may be reported by multiple people (patient, doctor, manufacturer), and some duplicates may remain in the data.

For these reasons, VAERS data is best used for signal detection — identifying potential safety concerns that warrant further investigation — rather than for definitive risk assessment. When VAERS surfaces a potential signal, it is investigated using more rigorous systems like the Vaccine Safety Datalink (VSD) and controlled epidemiological studies.

About This Data

All data on VaccineWatch comes from the official VAERS public-use datasets published by the CDC and FDA. Our current dataset covers reports from 1990 through early 2026. We process the raw data without filtering or editorializing — every metric is a transparent aggregation of official government data.

Our Methodology →FAQ →Disclaimer →

2026 Data Context

As VAERS reporting normalizes following the COVID-19 pandemic surge, the data landscape for commonly reported symptoms is shifting. Annual VAERS reports in 2025-2026 have returned to the 35,000-45,000 range typical of the pre-pandemic era (2015-2019), making year-over-year comparisons more meaningful again.

The HHS administration has signaled increased focus on vaccine safety data analysis, including the development of AI-powered tools for pattern detection in VAERS reports. While these tools are still under development, they represent a potential evolution in how adverse event data is analyzed and interpreted.

New vaccines entering the market — including RSV vaccines for older adults and pregnant women, updated COVID-19 formulations, and potential H5N1 avian flu vaccines — continue to add new data streams to VAERS. Each new vaccine type provides additional context for understanding commonly reported symptoms across the full spectrum of vaccine safety surveillance.

Limitations of This Analysis

This analysis is based entirely on VAERS passive surveillance data, which carries important limitations that must be understood:

  • Underreporting: Studies estimate that only 1-10% of adverse events are reported to VAERS. This means the true number of events is likely much higher than what appears in the data.
  • Stimulated reporting: Media coverage and public awareness can temporarily increase reporting rates for specific vaccines, independent of any change in actual safety.
  • No control group: VAERS does not include a comparison group of unvaccinated individuals, making it impossible to determine whether reported events occurred at a higher rate than expected.
  • Variable data quality: VAERS reports range from detailed medical records submitted by healthcare providers to brief descriptions from patients. Not all reports are verified for medical accuracy.
  • Duplicate reports: The same event may be reported by multiple people (patient, doctor, manufacturer), and some duplicates may remain in the data.

For these reasons, VAERS data is best used for signal detection — identifying potential safety concerns that warrant further investigation — rather than for definitive risk assessment. When VAERS surfaces a potential signal, it is investigated using more rigorous systems like the Vaccine Safety Datalink (VSD) and controlled epidemiological studies.

About This Data

All data on VaccineWatch comes from the official VAERS public-use datasets published by the CDC and FDA. Our current dataset covers reports from 1990 through early 2026. We process the raw data without filtering or editorializing — every metric is a transparent aggregation of official government data.

Our Methodology →FAQ →Disclaimer →

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