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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.

  1. Home
  2. Symptoms
  3. Lethargy

Lethargy

18,435 total reports16.7% serious outcomes
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Lethargy appears in 18,435 VAERS reports across all vaccines. Of these, 505 reports also mentioned death and 2,579 involved hospitalization. The severity rate (deaths + hospitalizations as a percentage of reports) is 16.7%. The top vaccines associated with this symptom are COVID19, DTAP, HIBV. Remember: VAERS reports show temporal association, not causation.

18,435
Total Reports
505
Deaths
2,579
Hospitalizations
16.7
Severity Rate
% serious outcomes

About Lethargy Reports

Lethargy has been reported 18,435 times in VAERS from 1990 to 2026.

Of these reports, 505 were associated with death (2.74%) and 2,579 involved hospitalization.

The overall serious outcome rate (death or hospitalization) for reports mentioning Lethargy is 16.7%.

Understanding Lethargy in VAERS

•Temporal association only: These reports show Lethargy occurred after vaccination, not necessarily because of vaccination.
•Background rates matter: Many symptoms occur naturally at baseline rates in the population, unrelated to vaccination.
•Reporting variability: Medical terminology may be used differently by various healthcare providers and over time.
•Investigation needed: High-frequency reports may trigger further epidemiological studies to determine causation.

What This Data Shows

Most Associated Vaccines: The vaccines most frequently mentioned in reports with Lethargy. This may reflect usage patterns, not causation.
Severity Patterns: The percentage of reports that involve serious outcomes can help prioritize safety investigations.
Reporting Trends: Changes in reporting frequency over time may reflect increased awareness, media attention, or actual safety signals.

Most Associated Vaccines

1. COVID1910,936
2. DTAP1,693
3. HIBV1,428
4. IPV1,338
5. VARZOS1,337
6. PNC1,247
7. MMR1,114
8. HEP894
9. RV5887
10. FLU3870
View all vaccines →

Detailed Breakdowns

Lethargy × COVID19 →Lethargy × DTAP →Lethargy × HIBV →

Quick Facts

Reports:18,435
Deaths:505
Hospitalizations:2,579
Mortality Rate:2.74%
Severity Rate:16.7%

Related Analysis

Most Common Symptoms Analysis →Serious Outcomes Analysis →When Do Side Effects Start? →Recovery Rates Analysis →

Explore Further

Compare with Other SymptomsRead Symptoms Analysis

Data Source

This data comes from the Vaccine Adverse Event Reporting System (VAERS), jointly managed by CDC and FDA.