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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.

⚠️

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. Vaccine Side Effects
  3. Varicella (Chickenpox) Vaccine
5 min read
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Varicella (Chickenpox) Vaccine Side Effects

The varicella vaccine (Varivax) protects against chickenpox and is given as two doses in childhood. With over 93,000 VAERS reports, it's one of the most-reported childhood vaccines — largely reflecting its widespread use since FDA approval in 1995.

116,688
Total Reports
353
Deaths Reported
3,868
Hospitalizations
33,689
ER Visits

Most Commonly Reported Side Effects

The following symptoms are most frequently reported after varicella vaccination:

#1No adverse event
15,409
#2Pyrexia
14,829
#3Injection site erythema
12,411
#4Rash
10,701
#5Infection
8,519
#6Drug ineffective
8,148
#7Injection site swelling
7,919
#8Erythema
6,875
#9Dermatitis bullous
5,952
#10Product storage error
5,701
#11Pruritus
5,292
#12Incorrect product storage
5,193

Varivax vs ProQuad (MMRV)

Varicella protection is available as standalone Varivax or combined with MMR as ProQuad (MMRV). ProQuad has a slightly higher rate of febrile seizures in children 12-23 months compared to giving MMR and varicella separately, which is why the CDC allows either approach for the first dose.

Expected Side Effects

Common (occurring in >10% of recipients):

  • Pain, redness, or swelling at injection site
  • Fever (usually mild, within 42 days)
  • Mild varicella-like rash (about 4% of children) — usually just a few spots

Less common:

  • Irritability
  • Upper respiratory symptoms
  • Headache and fatigue

Rare:

  • Febrile seizures (slightly higher with MMRV vs separate vaccines)
  • Herpes zoster (shingles) from vaccine-strain virus — much rarer than from natural chickenpox
  • Pneumonia, encephalitis (extremely rare)
  • Severe allergic reaction

Important Context

Before the varicella vaccine, chickenpox caused about 100 deaths and 10,000+ hospitalizations per year in the U.S. Since routine vaccination began in 1995, chickenpox cases have declined by over 90%. The vaccine's benefits in preventing natural chickenpox complications far exceed the risks of reported adverse events.

Many VAERS reports for varicella involve co-administered vaccines (given at the same visit), making it difficult to attribute symptoms to any single vaccine.

The chickenpox vaccine is given in two childhood doses. See exactly when each is due on the CDC vaccine schedule, review our 2026 vaccine schedule analysis, and explore pediatric VAERS patterns.

⚠️ Remember: VAERS reports show correlation, not causation. A report filed after vaccination doesn't mean the vaccine caused the reported event. Always consult your healthcare provider for medical advice.

Explore This Data

Varicella Vaccine Detail →
Full VAERS profile
MMRV (ProQuad) →
Combined vaccine data
All Side Effects →
Overview across all vaccines

2026 Safety Monitoring Update

As of mid-2026, the varicella (chickenpox) vaccine continues to be monitored through VAERS and complementary surveillance systems including the Vaccine Safety Datalink (VSD) and the Clinical Immunization Safety Assessment (CISA) project. No new safety signals have been identified in recent data that would change the established safety profile of this vaccine.

The HHS administration's announced development of AI-powered VAERS analysis tools may provide additional insights into varicella (chickenpox) vaccine adverse event patterns. These tools aim to detect subtle signals that traditional statistical methods might miss, though their implementation timeline and methodology remain under development.

It's worth noting that VAERS reporting for routine vaccines like varicella (chickenpox) has remained stable through the post-pandemic period. While COVID-19 vaccine reports surged and then declined, reporting patterns for established childhood and adult vaccines have been remarkably consistent, suggesting that the VAERS system continues to function as designed for ongoing safety surveillance.

Understanding VAERS Data for varicella (chickenpox)

When interpreting VAERS data for varicella (chickenpox) vaccines, several key principles apply:

  • Reports ≠ Causation: A VAERS report means an event occurred after vaccination. It does not establish that the vaccine caused the event. Many reported symptoms are common health occurrences that would happen regardless of vaccination.
  • No denominator: VAERS does not track the number of doses administered. Without knowing how many people received the vaccine, raw report counts cannot be used to calculate risk rates or compare safety across vaccines.
  • Co-administration: Many vaccines are given at the same visit. When a VAERS report lists multiple vaccines, it's impossible to determine which vaccine (if any) was responsible for the reported adverse event.
  • Reporting variability: Healthcare provider awareness, media attention, and public concern all influence how many reports are filed. Changes in report volume may reflect changes in reporting behavior rather than changes in actual safety.

How to Use This Data Responsibly

VAERS data is most useful as a starting point for conversation with your healthcare provider, not as a basis for medical decisions. If you're concerned about varicella (chickenpox) vaccine side effects:

  • Discuss your specific risk factors with your doctor or pharmacist
  • Ask about the relative risks of the disease the vaccine prevents vs. the vaccine itself
  • Consider your age, health status, and any previous vaccine reactions
  • Remember that clinical trials and post-market studies provide much stronger safety evidence than VAERS alone

For the most up-to-date safety information, consult the CDC's vaccine information pages or speak with a qualified healthcare professional.

More Resources

When Do Side Effects Start?
73% occur within 3 days of vaccination
Serious vs Non-Serious Outcomes
The full severity spectrum in VAERS
Report an Adverse Event
How to file a VAERS report
Our Methodology
How we process VAERS data

2026 Safety Monitoring Update

As of mid-2026, the varicella (chickenpox) vaccine continues to be monitored through VAERS and complementary surveillance systems including the Vaccine Safety Datalink (VSD) and the Clinical Immunization Safety Assessment (CISA) project. No new safety signals have been identified in recent data that would change the established safety profile of this vaccine.

The HHS administration's announced development of AI-powered VAERS analysis tools may provide additional insights into varicella (chickenpox) vaccine adverse event patterns. These tools aim to detect subtle signals that traditional statistical methods might miss, though their implementation timeline and methodology remain under development.

It's worth noting that VAERS reporting for routine vaccines like varicella (chickenpox) has remained stable through the post-pandemic period. While COVID-19 vaccine reports surged and then declined, reporting patterns for established childhood and adult vaccines have been remarkably consistent, suggesting that the VAERS system continues to function as designed for ongoing safety surveillance.

Understanding VAERS Data for varicella (chickenpox)

When interpreting VAERS data for varicella (chickenpox) vaccines, several key principles apply:

  • Reports ≠ Causation: A VAERS report means an event occurred after vaccination. It does not establish that the vaccine caused the event. Many reported symptoms are common health occurrences that would happen regardless of vaccination.
  • No denominator: VAERS does not track the number of doses administered. Without knowing how many people received the vaccine, raw report counts cannot be used to calculate risk rates or compare safety across vaccines.
  • Co-administration: Many vaccines are given at the same visit. When a VAERS report lists multiple vaccines, it's impossible to determine which vaccine (if any) was responsible for the reported adverse event.
  • Reporting variability: Healthcare provider awareness, media attention, and public concern all influence how many reports are filed. Changes in report volume may reflect changes in reporting behavior rather than changes in actual safety.

How to Use This Data Responsibly

VAERS data is most useful as a starting point for conversation with your healthcare provider, not as a basis for medical decisions. If you're concerned about varicella (chickenpox) vaccine side effects:

  • Discuss your specific risk factors with your doctor or pharmacist
  • Ask about the relative risks of the disease the vaccine prevents vs. the vaccine itself
  • Consider your age, health status, and any previous vaccine reactions
  • Remember that clinical trials and post-market studies provide much stronger safety evidence than VAERS alone

For the most up-to-date safety information, consult the CDC's vaccine information pages or speak with a qualified healthcare professional.

More Resources

When Do Side Effects Start?
73% occur within 3 days of vaccination
Serious vs Non-Serious Outcomes
The full severity spectrum in VAERS
Report an Adverse Event
How to file a VAERS report
Our Methodology
How we process VAERS data

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