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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. Vaccines
  3. Smallpox (Acam2000)
  4. Encephalitis
Smallpox (Acam2000)×Encephalitis

Encephalitis Reports for Smallpox (Acam2000)

#159 most reported symptom for this vaccine

54
Reports
0
Deaths
33
Hospitalizations
0
Mortality Rate
%
61.1
Hosp. Rate
%

Encephalitis and Smallpox (Acam2000)

Encephalitis has been reported 54 times in association with Smallpox (Acam2000) vaccination in VAERS. This represents 0.6% of all 8,768 reports for this vaccine.

Among these reports, 0 mentioned death (0.00%) and 33 involved hospitalization (61.1%).

Encephalitis is the #159 most frequently reported symptom for Smallpox (Acam2000) out of 1393 total symptoms.

Disclaimer: VAERS reports describe events that occurred after vaccination but do not establish that the vaccine caused the event. Many reported symptoms may be coincidental or related to underlying conditions.

What This Means

Seeing 54 reports of Encephalitis after Smallpox (Acam2000) vaccination may seem alarming, but context is critical.

The mortality rate among these reports is very low at 0.00%, suggesting most cases are non-fatal.

Important Context

•Association, not causation: These reports show Encephalitis occurred after vaccination, not that the vaccine caused it.
•Background rates: Encephalitis may occur naturally at baseline rates in the population, unrelated to vaccination.
•Anyone can report: VAERS accepts reports from anyone — patients, parents, healthcare providers — without requiring medical verification.
•Denominator missing: VAERS counts reports, not rates per dose. Without knowing how many doses were given, raw counts can be misleading. Learn more →

Similarly Ranked Symptoms

Nasal congestion55 reportsRhinorrhoea55 reportsPallor54 reportsUpper respiratory tract infection54 reports

Quick Facts

Reports:54
Deaths:0
Hospitalizations:33
% of Vaccine:0.6%
Rank:#159 of 1393

Related Pages

Smallpox (Acam2000) OverviewEncephalitis (All Vaccines)Why Raw Numbers MisleadTop Symptoms Analysis

Data Source

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