1. Basic Information

Disease Protected Against

Coronavirus Disease 2019 (COVID-19), caused by SARS-CoV-2, ranges from asymptomatic infection to severe respiratory failure, multiorgan dysfunction, and death. Children generally experience milder acute disease than adults, but severe outcomes — including MIS-C (Multisystem Inflammatory Syndrome in Children), hospitalization, and death — occur. As of 2024, COVID-19 remains a leading cause of pediatric respiratory hospitalization during seasonal waves. Post-acute sequelae ("Long COVID") are reported in children at lower rates than adults but are not negligible (~1–5% prevalence estimates vary by case definition and study design).

CDC Schedule (U.S., 2025)

Population	Recommendation
All persons ≥6 months	Universal recommendation for COVID-19 vaccination; updated formulations matched to circulating variants
Children 6 months–4 years (unvaccinated)	2–3 dose primary series (depending on product and age)
Children 6 months–4 years (previously vaccinated)	1 dose of updated vaccine
Children ≥5 years (unvaccinated)	1 dose of updated mRNA vaccine, or 2-dose Novavax primary series
Children ≥5 years (previously vaccinated)	1 dose of updated vaccine
Immunocompromised	Additional doses per ACIP guidance

Source: CDC ACIP, 2025 schedule. As of the 2024–25 season, updated vaccine formulations target circulating variants (transitioning from the bivalent BA.4/5 formulation to monovalent formulations matched to Omicron sublineages such as JN.1, KP.2, etc.).

Licensed/Authorized Products (U.S., Pediatric)

Comirnaty^® (Pfizer-BioNTech, BNT162b2) — mRNA vaccine. Licensed for ages ≥12 (August 2021); EUA for ages 6 months–11 years. Encodes the SARS-CoV-2 spike protein. Lipid nanoparticle (LNP) formulation.
Spikevax^® (Moderna, mRNA-1273) — mRNA vaccine. Licensed for ages ≥18; EUA for ages 6 months–17 years. Also spike-protein-encoding mRNA in LNP.
Novavax COVID-19 Vaccine (NVX-CoV2373) — Recombinant spike protein subunit vaccine with Matrix-M adjuvant. Authorized for ages ≥12. Represents a non-mRNA option using more traditional protein-based technology.
Janssen COVID-19 Vaccine (Johnson & Johnson, Ad26.COV2.S) — Adenoviral vector vaccine. No longer available in the U.S. (EUA revoked June 2023). Noted here for completeness because safety signals identified with this product (TTS/VITT — thrombosis with thrombocytopenia syndrome) are important to the overall COVID-19 vaccine safety narrative.

2. Temporal Distribution: When Adverse Events Are Reported

Understanding when adverse events cluster post-vaccination helps distinguish vaccine-related reactions from coincidental illness. Two independent surveillance systems — VAERS (passive reports) and V-SAFE (active surveillance app) — show similar temporal patterns, validating the timing windows.

VAERS vs V-SAFE: Side-by-Side Comparison

VAERS Data (Passive Reporting)

Total Reports: 2,478 (10 key conditions)
Peak Day: Day 4 (203 reports, 15.3%)
Within 7 days: 917 reports (73%)
Within 14 days: 1,145 reports (92%)
Spontaneous reports from healthcare providers and public. Likely underreporting.

V-SAFE Data (Active Surveillance)

Total Records: 167,988 (from 518,511 surveyed)
Peak Day: Day 3 (91,522 reports, 54.5%)
Within 7 days: 117,208 reports (69.8%)
Within 14 days: 141,669 reports (84.3%)
CDC-sponsored smartphone app. Structured, higher completeness.

✓ Key Finding: Both independent systems show 84-92% of reports cluster within 0-14 days post-vaccination. Similar temporal patterns across different collection methods validates that adverse events peak early and taper rapidly, consistent with direct vaccine-reaction mechanisms rather than coincidental illness.

Temporal Distribution Histogram

Side-by-side comparison: VAERS (red) and V-SAFE (blue) showing percentage of adverse event reports by days post-vaccination. Source: CDC VAERS (2021-2024) and V-SAFE FOIA 12th Final Release (2021-2026).

Clinical Interpretation

Day 0-3 (Acute Phase): Immediate and early reactions (anaphylaxis, myocarditis). V-SAFE peak at day 3 reflects maximal reporting of acute systemic symptoms.
Day 4-7 (Immune Response Window): Peak window for delayed immune-mediated reactions (Guillain-Barré syndrome, Bell's palsy, thrombocytopenia). VAERS peak at day 4 captures this window.
Day 8-14 (Tail-off): Reports decline rapidly. 84-92% threshold indicates most vaccine-related reactions manifest within 2 weeks.
Day 15-30 (Late Phase): Remaining reports likely represent either late manifestations (myocarditis complications, thrombosis) or coincidental illness.
After Day 30: Reports become increasingly rare, suggesting minimal temporal association with vaccination.

Data Quality & Limitations

VAERS: Spontaneous passive system; underreporting is documented. No denominator (total doses) limits rate calculations. Reports span 2021-2024.
V-SAFE: Active CDC-sponsored surveillance from smartphone app. Higher completeness but selection bias (participants must download app). 518,511 responses analyzed; 32.4% have explicit timing data.
Temporal Window Assignment: Based on clustering patterns: early-onset AEs (anaphylaxis, myocarditis) 0-7 days; delayed neurological 7-42 days. Outliers beyond day 30 likely unrelated.
Causality vs. Temporal Association: Clustering does NOT prove causation. Confounding, reporting bias, and coincidental illness all affect interpretation. See individual adverse event pages for causality assessment.

Ingredients (Package Insert)

Structured composition for 3 branded products covered on this page, taken from FDA-approved package inserts (DailyMed / manufacturer prescribing information). Lists are per product — formulations differ by manufacturer and presentation. Click an ingredient name to open its safety-context page when available.

Recombinant protein mRNA Intramuscular (IM) No preservative (typical single-dose) Lipid nanoparticle (LNP) Adjuvant: Matrix-M Protein nanoparticle Polysorbate 80

Comirnaty (Pfizer-BioNTech COVID-19 Vaccine, mRNA) Pfizer Inc. / BioNTech · mRNA

Delivery

Route: Intramuscular (IM)

Form: Suspension for injection

Dose volume: 0.3 mL (standard adult/adolescent presentations)

Presentation: single-dose vial or prefilled syringe (formulation-dependent)

Encapsulation / delivery vehicle

Lipid nanoparticle (LNP) — Nucleoside-modified mRNA encapsulated in lipid nanoparticles (LNP) for cellular delivery.

Component	Role	Amount
ALC-0315 ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)	ionizable lipid	0.43 mg per 0.3 mL (30 mcg mRNA adult presentation)
ALC-0159 (2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide)	pegylated lipid	0.05 mg per 0.3 mL (30 mcg presentation)
DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine)	helper phospholipid	0.09 mg per 0.3 mL
Cholesterol	cholesterol	0.19 mg per 0.3 mL

Lipid amounts scale with mRNA dose (e.g. lower for pediatric presentations).

Antigens

Antigen	Type	Amount / dose
Nucleoside-modified mRNA encoding SARS-CoV-2 spike (S) glycoprotein System: synthetic nucleoside-modified mRNA	mRNA	30 mcg (12+ years standard); 10 mcg (5–11 years) — seasonal formula strain updates

Adjuvants

None listed on the package insert for this product (common for live attenuated and some inactivated whole-virus vaccines).

Preservatives

None — Single-dose presentation; label states no preservative.

Excipients & residuals

Ingredient	Category	Amount	Role
Tromethamine	Buffer	0.06 mg (current tromethamine formulation)	buffer
Tromethamine hydrochloride	Buffer	0.4 mg	buffer
Sucrose	Stabilizer	31 mg	cryoprotectant/stabilizer

LNP lipids are the delivery system, not classical adjuvants. PEGylated lipid is structurally related to PEG.

Source: FDA package insert · Verified 2026-07-09

Spikevax (Moderna COVID-19 Vaccine, mRNA) ModernaTX, Inc. · mRNA

Delivery

Route: Intramuscular (IM)

Form: Suspension for injection

Dose volume: 0.5 mL or 0.25 mL (age/formula-dependent)

Presentation: single-dose or multi-dose vial / prefilled syringe

Encapsulation / delivery vehicle

Lipid nanoparticle (LNP) — mRNA embedded in SM-102 lipid nanoparticles.

Component	Role	Amount
SM-102 (heptadecan-9-yl 8-{(2-hydroxyethyl)[6-oxo-6-(undecyloxy)hexyl]amino}octanoate)	ionizable lipid	part of total lipid content (label)
PEG2000-DMG (1,2-dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000)	pegylated lipid	part of total lipid content
DSPC	helper phospholipid	part of total lipid content
Cholesterol	cholesterol	part of total lipid content

Antigens

Antigen	Type	Amount / dose
Nucleoside-modified mRNA encoding SARS-CoV-2 spike (S) glycoprotein System: synthetic nucleoside-modified mRNA	mRNA	varies by age and seasonal formula (e.g. 50 mcg / 25 mcg presentations)

Adjuvants

None listed on the package insert for this product (common for live attenuated and some inactivated whole-virus vaccines).

Preservatives

None — Single-dose presentation; label states no preservative.

Excipients & residuals

Ingredient	Category	Amount	Role
Trometamol (tromethamine)	Buffer	label quantity	buffer
Trometamol hydrochloride	Buffer	label quantity	buffer
Acetic acid	Buffer	label quantity	pH
Sodium acetate trihydrate	Buffer	label quantity	buffer
Sucrose	Stabilizer	label quantity	stabilizer
Water for injection	Diluent	q.s.	vehicle

Source: FDA package insert · Verified 2026-07-09

Nuvaxovid (Novavax COVID-19 Vaccine, Adjuvanted) Novavax, Inc. · Recombinant protein

Delivery

Route: Intramuscular (IM)

Form: Suspension for injection

Dose volume: 0.5 mL

Presentation: prefilled syringe

Encapsulation / delivery vehicle

Protein nanoparticle — Recombinant SARS-CoV-2 spike protein nanoparticles (non-infectious).

Antigens

Antigen	Type	Amount / dose
SARS-CoV-2 recombinant spike protein System: Sf9 insect cells / baculovirus system	Recombinant protein	5 mcg (typical labeled antigen mass; seasonal formula updates)

Adjuvants

Matrix-M — 50 mcg (typical)
Saponin-based adjuvant from Quillaja saponaria.

Preservatives

None — Single-dose presentation; label states no preservative.

Excipients & residuals

Ingredient	Category	Amount	Role
Polysorbate 80	Surfactant	label quantity	surfactant
Sodium chloride and buffer salts	Buffer	label quantity	vehicle

Protein subunit + Matrix-M adjuvant — no mRNA, no LNP.

Source: FDA package insert · Verified 2026-07-09

ⓘ How to read this section

Ingredient lists are sourced from official package inserts for the specific brands named above. Formulations can change between lots and over time — verify against the current label before any clinical decision. Presence of a substance does not by itself indicate harm; toxicology is dose-, route-, and context-dependent. Browse the full ingredient database: Vaccine Ingredients index.

2. Pre-Licensure Clinical Trial Data

COVID-19 vaccines underwent the largest and most rapidly conducted pre-licensure clinical trial programs in history, under Emergency Use Authorization (EUA) frameworks that required demonstration of safety and efficacy but allowed for accelerated review timelines.

Pivotal Trial Data — Pediatric Populations

Product	Pediatric Pivotal Trial Size	Efficacy/Immunobridging
Pfizer (ages 12–15)	~2,260 (1,131 vaccine, 1,129 placebo); C4591001 trial	100% efficacy (95% CI 75–100) against symptomatic COVID-19; short follow-up period
Pfizer (ages 5–11)	~3,100 (2:1 randomization); immunobridging design	90.7% efficacy (95% CI 67.7–98.3)
Pfizer (ages 6 months–4 years)	~4,500 (3-dose series); immunobridging	Immunobridging to young adults met; limited clinical efficacy data due to low case counts
Moderna (ages 12–17)	~3,700	~93% efficacy (against original strains); immunobridging met
Moderna (ages 6–11)	~4,000; immunobridging	Immunobridging met
Moderna (ages 6 months–5 years)	~6,400 (2-dose series); immunobridging	Immunobridging met; efficacy against symptomatic infection ~37–51% during Omicron

Note: Efficacy estimates were generated during periods of specific variant predominance (e.g., original strain, Alpha, Delta). Effectiveness against Omicron sublineages and more recent variants is lower, particularly against infection, though protection against severe disease is better preserved.

Most Common Adverse Reactions (mRNA Vaccines, Children)

Reaction	Adolescents (12–17)	Children (5–11)	Young Children (6m–4y)
Injection site pain	~80–90%	~70–80%	~30–50%
Fatigue	~50–65%	~35–45%	~25–35%
Headache	~45–60%	~25–35%	~10–15%
Myalgia	~35–50%	~15–25%	~8–12%
Fever	~10–20%	~8–15%	~8–15%
Chills	~25–35%	~8–12%	~3–5%

Sources: Pfizer and Moderna pivotal trial data; FDA VRBPAC briefing documents. Reactogenicity is generally dose-dependent (higher with the second dose of a primary series; data on updated formulations are more limited). Adverse reactions in children are less frequent and less severe than in adults.

Key Limitations of Pre-Licensure Trial Data

Short follow-up duration: The median safety follow-up in the pediatric EUA submissions was ~2–3 months post-dose 2. This was adequate to detect common acute adverse events but inherently limited for evaluating long-term outcomes or rare events with longer latency.
Small sample sizes relative to adult trials: Pediatric trials were substantially smaller than the adult pivotal trials (Pfizer adult: ~44,000; Pfizer 12–15: ~2,260). Rare adverse events — especially myocarditis, which occurs at ~1–10 per 100,000 in adolescent males — were not expected to be detected in pre-licensure pediatric trials.
Evolving variant landscape: Efficacy estimates from the pre-Omicron era are not directly applicable to current circulating variants. Effectiveness is now assessed primarily through post-licensure observational studies.
Immunobridging endpoints: Pediatric licensure was based primarily on immunobridging (demonstrating non-inferior neutralizing antibody titers compared to young adults in whom clinical efficacy was demonstrated), not direct clinical efficacy, with the exception of the 12–15-year Pfizer trial.

3. Post-Licensure Safety Data

Myocarditis / Pericarditis — Confirmed Safety Signal (mRNA Vaccines)

An elevated risk of myocarditis and pericarditis following mRNA COVID-19 vaccination (particularly the second dose) was identified in post-licensure surveillance beginning in mid-2021. This is the most significant confirmed pediatric safety signal for COVID-19 vaccines.

Highest-risk group: Adolescent and young adult males aged 12–29. Risk is highest after the second dose of a primary series.
Rate estimates (VSD and international data): Pfizer: ~2–10 cases per 100,000 doses in males aged 12–17; ~5–15 per 100,000 in males aged 18–29. Moderna: some data suggest a slightly higher rate than Pfizer (possibly ~2–3x higher in young adult males), though data in children are less extensive.
Risk after booster doses: Lower than after the second primary dose, though data are more limited.
Clinical course: The majority of cases are mild and self-limited, with symptom resolution within days to weeks and normal cardiac MRI findings at follow-up. However, a small proportion require ICU admission, and long-term cardiac outcomes are still being studied.
Comparison to COVID-19-associated myocarditis: Myocarditis risk following SARS-CoV-2 infection is substantially higher (~10–40x) than the risk following mRNA vaccination across most age/sex strata. COVID-19 infection itself is a well-established cause of myocarditis.

IOM / NASEM have not yet issued a comprehensive causality assessment for COVID-19 vaccines (as of the 2012 report which predates these products). The CDC and FDA have acknowledged the association and incorporated it into product labeling and clinical guidance.

Other VSD / Active Surveillance Findings (Pediatric)

Anaphylaxis: Estimated at ~2–5 per million doses for mRNA vaccines. Comparable to or slightly higher than rates for other vaccines.
Febrile seizures: A VSD study (Goddard et al., 2023) found a small increased risk of febrile seizures in children aged 2–5 following concomitant administration of mRNA COVID-19 vaccine and IIV (influenza). Rate was ~1 excess seizure per 2,500–4,000 concomitant administrations. The signal was not observed with COVID-19 vaccine alone or IIV alone.
Multisystem Inflammatory Syndrome in Children (MIS-C): No evidence that COVID-19 vaccination causes MIS-C. Multiple studies suggest vaccination reduces MIS-C risk, consistent with MIS-C being a post-infectious complication prevented by vaccination.
No increased risk for GBS, VTE, stroke, or other thromboembolic events identified with mRNA vaccines in children (unlike the Janssen TTS/VITT signal in adults, which is product-specific).

Janssen (J&J) Specific Safety Signals (Not a Pediatric Product; Noted for Context)

Thrombosis with Thrombocytopenia Syndrome (TTS/VITT): ~3–4 cases per million doses in adults (highest in females aged 30–49). Causal mechanism involves anti-PF4 antibodies. The J&J EUA was restricted (May 2022) and revoked (June 2023) in the U.S., in part due to this safety signal and the availability of safer alternatives (mRNA vaccines). TTS/VITT is not associated with mRNA vaccines.
GBS: A small increased risk of GBS (~3–5 per million doses) was observed with Janssen. Not associated with mRNA vaccines after extensive surveillance.

VAERS

VAERS Metric (COVID-19, cumulative U.S. data)	Approximate Figures
Total COVID-19 vaccine doses administered (U.S., through 2024)	>675 million doses
Total VAERS reports received for COVID-19 vaccines	>1.5 million (largest VAERS reporting volume for any vaccine in history, reflecting unprecedented scale and stimulated reporting)
Reports classified as "serious"	~6–8% of total reports

⚠ Critical Caveat

VAERS data represent unverified reports temporally associated with vaccination. A report to VAERS does not mean the vaccine caused the event. The COVID-19 vaccine VAERS database is the largest in history and has been extensively affected by stimulated/heightened reporting due to unprecedented public and media attention. Raw VAERS report counts for COVID-19 vaccines are particularly unsuitable for causal inference, and analyses using VAERS data to claim causality are scientifically invalid.

VAERS Reporting Data — Halma & Varon (2025), DARE-SAFE

The DARE-SAFE paper (Halma & Varon, Pharmacoepidemiology 2025, CC BY 4.0) analyzed VAERS reports for vaccines administered in the United States from 2006–2022. The following data are extracted from Table 1 of that paper for this vaccine (COVID-19 (all mRNA + adenoviral vector products combined). *Dose count from Our World in Data (2021–2022), not the CDC series — different source & time span than other rows (2006–2022 for all other vaccines). See full paper for manufacturer-level breakdowns (Pfizer, Moderna, J&J, Novavax).):

Metric	Value
U.S. doses administered (2006–2022)	663,000,000*
Total VAERS AE reports	781,075
AE reporting rate (per 100,000 doses)	117.7
Total death reports	11,288
Death reporting rate (per 100,000 doses)	1.70
AE-to-Death ratio	69:1

Source: Halma, M.; Varon, J. DARE-SAFE. Pharmacoepidemiology. 2025. DOI: 10.3390/pharma4020007. CC BY 4.0. Data from Table 1.

📚 Important Interpretive Caveats (from the paper itself)

Reporting rate ≠ incidence rate. VAERS is a passive, unverified system. A report means someone submitted a claim of temporal association, not a confirmed causal event. The paper is explicit that causality cannot be inferred from these numbers alone.
Reporting behavior is not uniform. More serious, unusual, or media-salient events are reported at much higher rates than mild ones. Products receiving more public, media, legal, and clinical attention (particularly COVID-19 vaccines, which also benefited from V-safe active-surveillance prompts and CICP compensation pathways) generate more reports per dose regardless of true risk.
Age and comorbidity confounding is not adjusted. COVID-19 vaccines were disproportionately administered to elderly and comorbid populations (nursing homes, 65+, high-risk groups in early 2021) with much higher background all-cause mortality than the general child/working-age population. Some fraction of temporally-associated deaths would occur regardless of vaccination, and the paper does not perform a background-rate comparison.
Stimulated reporting is a known, documented phenomenon. Media coverage, plaintiff attorney solicitation, and advocacy campaigns — all independently inflate VAERS reporting propensity. The paper cites this literature but does not correct for it.
Small-denominator rows are unreliable. Rates computed from small denominators (e.g., monovalent measles, DT, mumps, rubella) have enormous statistical uncertainty and should not be compared to vaccines with hundreds of millions of administered doses without noting the wide confidence intervals.

Source: Halma, M.; Varon, J. DARE-SAFE: Denominator-Adjusted Rate Estimates of Substance Adverse Events Frequency Evaluation in Pharmaceuticals and Vaccines. Pharmacoepidemiology. 2025, 4, 7. DOI: 10.3390/pharma4020007. CC BY 4.0.

Passive Surveillance: AE Type Breakdown (Multi-System)

Side-by-side view of U.S. VAERS, Health Canada Canada Vigilance, Japan JADER (PMDA), EU EudraVigilance, and live-scraped VigiAccess (WHO), Lareb (Netherlands), and DAEN (Australia) via SurVigilance. JADER: public CSV pmdacasereport202606. EudraVigilance: local EudraVigilance/ DAP exports. SurVigilance panels show MedDRA PT mention totals (not individual-case counts). Category assignment uses keyword matching — approximate, not official SOC coding. JADER reference (PDF)

VAERS (United States)

Canada Vigilance (Canada)

JADER (PMDA, Japan)

EudraVigilance (EU)

No matching vaccine cases in the current EudraVigilance DAP export.

SurVigilance: VigiAccess, Lareb & DAEN

VigiAccess (WHO)

Lareb (Netherlands)

DAEN (Australia)

VAERS (U.S., 2006–2024): 4,923,243 symptom mentions (371.29/100k doses). Largest share: Other / Unclassified (22%), General / Systemic (non-local) (18%), Neurological (12%). Canada Vigilance (CV Online extract): 60,469 reaction mentions in 12,929 unique reports (85.6% serious (11,070 of 12,929 reports)). Largest share: Cardiac / Cardiovascular (14%), Neurological (13%), General / Systemic (non-local) (12%). JADER (PMDA public CSV extract): 125,347 reaction mentions in 31,435 unique reports (10.9% serious (3,431 of 31,435 reports)). Largest share: Other / Unclassified (33%), Neurological (13%), General / Systemic (non-local) (12%). VigiAccess (WHO VigiBase): 18,107,554 reaction-term mentions · search: COVID-19. Largest share: General / Systemic (non-local) (23%), Neurological (17%), Other / Unclassified (13%). Lareb (Netherlands): 119,155 reaction-term mentions · search: COVID-19 vaccine. Largest share: Other / Unclassified (33%), Musculoskeletal (13%), Neurological (13%). DAEN (Australia): 470,194 reaction-term mentions · search: COVID-19 vaccine. Largest share: Neurological (21%), General / Systemic (non-local) (15%), Cardiac / Cardiovascular (11%). Cross-database note: All systems are passive and unverified; reporting rates are not directly comparable across countries (different populations, reporting incentives, and lack of dose denominators for Canada/Japan/EU). top VAERS: Other / Unclassified; top Canada Vigilance: Cardiac / Cardiovascular; top JADER: Other / Unclassified. SurVigilance note: VigiAccess, Lareb, and DAEN counts are live-scraped MedDRA PT mention totals (not deduplicated individual cases). Data via SurVigilance (GPL-3.0). Category assignment uses keyword matching on reported reaction terms — approximate and exploratory. Neither database establishes causality.

Compare AE patterns across all vaccines →

Pharmacovigilance Lot Signal Detection — Hypothesis-Generating Only

Multi-system context below. VAERS (U.S.) supports lot-level volume z-scores and seriousness flags by product and lot (2006–2024). Each lot links to a summary with report count, seriousness %, adverse-event pie chart, U.S. state map, and timeline. A signal flag means a statistical threshold was exceeded — not that a lot is unsafe. Full dashboard →

VAERS flags: VOL high report volume (z ≥ 3) · BURST clustered in <90 days · SER serious reports >50%. Lot numbers are voluntary/incomplete in VAERS. Location data is U.S. state only (no postal codes in the public extract).

VAERS (United States) — all lots by product

714,061 reports with usable lot across 6,145 lots · 629 flagged

Loading lot tables…

Other Pharmacovigilance Systems

Lot-level analysis is only possible where reporters supply batch/lot numbers in the public extract. Canada Vigilance, JADER (PMDA, Japan), and most other national systems publish product-level spontaneous reports without lot fields.

Canada Vigilance (Health Canada)

12,929 unique reports · 60,469 reaction mentions · 85.6% serious (11,070 of 12,929 reports). Top categories: Cardiac / Cardiovascular (14%), Neurological (13%), General / Systemic (non-local) (12%).

Canada Vigilance spontaneous reports are unverified temporal associations. The public CV Online data extract does not include lot or batch numbers, so lot-level signal detection is not possible for this system — only product-level reaction patterns are shown here. No Canadian dose denominators are available. Extract 2026-03-31.

Search Canada Vigilance →

JADER (PMDA, Japan)

31,435 unique reports · 125,347 reaction mentions · 10.9% serious (3,431 of 31,435 reports). Top categories: Other / Unclassified (33%), Neurological (13%), General / Systemic (non-local) (12%).

JADER (Japanese Adverse Drug Event Report database) spontaneous reports are unverified temporal associations; PMDA has not assessed causality per case. The public CSV extract does not include lot or batch numbers, so lot-level signal detection is not possible — only product-level reaction patterns are shown here. Reaction terms in source data use MedDRA/J Preferred Terms. JADER CSV extract pmdacasereport202606 (2026-06). JADER reference (PDF)

Search JADER / PMDA adverse reactions →

No EudraVigilance (EU) summary is mapped for this page.

VigiAccess (WHO)

18,107,554 MedDRA PT mentions · search: COVID-19. Top categories: General / Systemic (non-local) (23%), Neurological (17%), Other / Unclassified (13%).

Live-scraped public portal data via SurVigilance (GPL-3.0). Counts are reaction-term mentions, not deduplicated individual cases. No lot/batch field.

Search VigiAccess (WHO) →

Lareb (Netherlands)

119,155 MedDRA PT mentions · search: COVID-19 vaccine. Top categories: Other / Unclassified (33%), Musculoskeletal (13%), Neurological (13%).

Live-scraped public portal data via SurVigilance (GPL-3.0). Counts are reaction-term mentions, not deduplicated individual cases. No lot/batch field.

Search Lareb (Netherlands) →

DAEN (Australia)

470,194 MedDRA PT mentions · search: COVID-19 vaccine. Top categories: Neurological (21%), General / Systemic (non-local) (15%), Cardiac / Cardiovascular (11%).

Live-scraped public portal data via SurVigilance (GPL-3.0). Counts are reaction-term mentions, not deduplicated individual cases. No lot/batch field.

Search DAEN (Australia) →

System	Region	Lot data
VAERS	United States	Lot data
Canada Vigilance	Canada	No public lot field
JADER (PMDA, Japan)	Japan	No public lot field
Lareb (Netherlands)	Netherlands	No public lot field
EudraVigilance	European Union	No public lot field
VigiAccess (WHO)	Global	No public lot field
Yellow Card (UK)	United Kingdom	No public lot field
DAEN (Australia)	Australia	No public lot field

All global data sources → · Data schemas →

Active Pharmacovigilance (Defined-Population Surveillance)

Curated findings for COVID-19 vaccines from active systems (not VAERS). Page inventory last reviewed: 2026-07-10.

ⓘ Active vs. passive — why this pane is separate

The VAERS / multi-system charts above are passive surveillance: spontaneous, unverified reports without a fixed denominator. Active surveillance starts from a defined, enumerated population (EHR/claims or structured post-vaccination surveys), applies pre-specified statistical tests, and asks whether an outcome occurs more often than expected in a risk window versus a comparison window or group. These are not two flavors of the same evidence — active findings are the harder tier that can confirm, refute, or leave under investigation a signal first hinted in passive data. Do not add VAERS report counts to active incidence rates.

○ No signal detected ◐ Signal under investigation ◑ Investigated — not confirmed ● Signal confirmed (true association) – Not currently under active surveillance

Dense Tier 1 and Tier 2 coverage since 2020–2021. VSD RCA is internal; findings are public via ACIP slides, MMWR, and peer-reviewed papers.

CDC Vaccine Safety Datalink (VSD)

Outcome: Myocarditis / pericarditis

Tier 2 ● Signal confirmed (true association)

VSD detected elevated myocarditis rates after mRNA COVID-19 vaccination (especially dose 2 in young males). Signal investigated extensively and confirmed as a true association; informed clinical guidance and risk communication. Incidence remains rare relative to doses administered.

Population

VSD sites; elevated risk primarily ages 12–39, higher after dose 2 mRNA in adolescent/young adult males

Risk interval

0–7 days post-vaccination (primary analytic window used in RCA presentations)

Comparison

Concurrent vaccinated comparators / later post-vaccination control windows (study-dependent)

Evaluation period

2021–ongoing (peak detection 2021–2022)

Method

Rapid Cycle Analysis — vaccinated concurrent / risk-interval designs with chart validation

Related passive AE category on this page: Cardiac / Cardiovascular (see multi-system charts above — not additive with active rates).

Sources: Klein NP et al. Rapid cycle analysis — myocarditis and anaphylaxis (CDC stack) · CDC VSD overview — monitoring methods

Record last reviewed: 2026-07-10

CDC Vaccine Safety Datalink (VSD)

Outcome: Ischemic stroke (selected bivalent booster subgroups)

Tier 2 ◑ Investigated — not confirmed

An initial statistical signal for ischemic stroke in a bivalent booster subgroup was investigated further across VSD and complementary data sources. Follow-up analyses did not confirm a consistent elevated risk warranting a causal attribution; monitoring continued as standard practice.

Population

VSD sites; adults 65+ receiving certain bivalent boosters (signal first noted in a specific age/formulation subgroup)

Risk interval

1–21 days post-vaccination (as presented in ACIP materials for the initial signal)

Comparison

Later post-vaccination window (e.g., 22–42 or 43–63 days; analysis-dependent)

Evaluation period

2022–2023

Method

Rapid Cycle Analysis / self-controlled and multi-source follow-up

Related passive AE category on this page: Cardiac / Cardiovascular (see multi-system charts above — not additive with active rates).

Sources: CDC — COVID-19 vaccine safety surveillance overview · CDC VSD

Record last reviewed: 2026-07-10

AusVaxSafety (Australia)

Outcome: Short-term solicited adverse events (medical attendance / selected serious outcomes)

Tier 1 ○ No signal detected

AusVaxSafety active survey surveillance of COVID-19 vaccines in Australia has repeatedly reported short-term safety profiles consistent with known reactogenicity; large respondent samples with low rates of medical care-seeking after vaccination in published analyses. Check brand-specific public pages for the latest formulation.

Population

Australian vaccinees participating in AusVaxSafety after COVID-19 vaccination (multi-brand program)

Risk interval

Days 0–3 and follow-up survey windows per protocol

Comparison

Internal signal thresholds / historical expected rates (system methods)

Evaluation period

2021–ongoing (public safety-data pages updated periodically)

Sample size

Published early-program analyses included multi-million survey responses (see citations)

Method

Active SMS/email post-vaccination surveys; sentinel clinics; published signal-detection methods

Sources: AusVaxSafety — COVID-19 vaccine safety data · Deng L et al. Med J Aust 2022 — AusVaxSafety short-term safety

Record last reviewed: 2026-07-10

Update cadence: Tier 1: check AusVaxSafety monthly when public pages update. Tier 2/3: quarterly review around ACIP meetings and PubMed/MMWR; set lastReviewed per record. Source tiers: Tier 1 = public near-real-time dashboards (e.g. AusVaxSafety); Tier 2 = VSD / Sentinel / PRAC-type findings released via ACIP slides, MMWR, or papers (no public VSD raw dashboard); Tier 3 = regulator label/safety communications. Detecting a signal and later classifying it as not confirmed is normal system behavior — not an anomaly to hide or amplify.

4. Documented Adverse Events — Evidence of Association

▶ Adverse Events with Strong Evidence of Causal Association (mRNA Vaccines)

Myocarditis / pericarditis: ~2–10 per 100,000 doses in males aged 12–17 after dose 2. Risk is higher with Moderna vs. Pfizer in some datasets. Clinical course is generally mild, but long-term outcomes are still being studied. Risk from SARS-CoV-2 infection is substantially higher. Strong
Injection site reactions: 80–90% (pain) in adolescents; lower in young children. Strong
Systemic reactogenicity: Fatigue (50–65%), headache (45–60%), myalgia (35–50%), fever (10–20%) in adolescents after dose 2. Strong
Anaphylaxis: ~2–5 per million doses. Strong
Lymphadenopathy (axillary): Tender lymphadenopathy in the ipsilateral axilla, observed in ~5–15% of vaccinees. Self-limited; can cause false-positive findings on mammography and other imaging. Strong
TTS/VITT (Janssen only — not a pediatric product): ~3–4 per million doses in adults. Causal via anti-PF4 antibodies. Not associated with mRNA vaccines. Strong (Janssen-specific)

▶ Adverse Events with Moderate or Preliminary Evidence

Febrile seizures (mRNA + concomitant IIV): ~1 per 2,500–4,000 concomitant administrations in children 2–5. Season-specific signal. Moderate
Long-term cardiac outcomes post-myocarditis: The acute course of mRNA vaccine-associated myocarditis is generally mild, but studies of cardiac function, fibrosis, and exercise tolerance at 1–5 years post-event are ongoing. Limited data preclude firm conclusions about lifelong cardiac risk. Preliminary
Menstrual irregularities: Multiple observational studies have reported transient changes in menstrual cycle length (~1–2 days) following vaccination. Mechanism uncertain. Changes appear temporary. Moderate

▶ Published Evidence Does Not Support a Causal Association (mRNA Vaccines)

Infertility (male or female): No evidence of an association. CDC, ACOG, ASRM, and multiple large studies have found no impact on fertility parameters. No Association
Adverse pregnancy outcomes: Multiple large registry studies (V-safe, VSD, international) have found no increased risk of miscarriage, stillbirth, preterm birth, or congenital anomalies. mRNA vaccination during pregnancy is recommended by ACOG and CDC. No Association
GBS (mRNA vaccines): After extensive VSD and international surveillance, no increased risk of GBS has been identified with mRNA vaccines (unlike Janssen). No Association
Death (all-cause mortality): No evidence of increased all-cause mortality associated with mRNA vaccination. Multiple large international studies. No Association
MIS-C: Vaccination does not cause MIS-C and reduces MIS-C risk by preventing SARS-CoV-2 infection. No Association

5. Disease Prevention Benefits

5a. Pre-Vaccine vs. Post-Vaccine Era (Children & Adolescents, U.S.)

Metric	Pre-Vaccine Era (2020–2021, Pre-Rollout for Children)	Post-Vaccine Era
Pediatric COVID-19 hospitalizations (ages 6 months–17)	Peak monthly hospitalization rates of ~1–5 per 100,000 (varies by wave)	Substantially reduced in vaccinated children; VE against pediatric hospitalization ~40–70% during Omicron (protection wanes over time, updated formulations partially restore it)
MIS-C incidence	~300–500 cases/month during Delta/Omicron waves	>80–90% reduction; MIS-C is now rare, predominantly in unvaccinated children
Pediatric COVID-19 deaths	~1,000–1,500 total pediatric deaths (2020–2023 cumulative)	Ongoing but concentrated in unvaccinated children; vaccination reduces death risk
SARS-CoV-2 seroprevalence (children)	~0% (2020)	>95% by 2023 (combined infection- and vaccine-induced)

Source: CDC COVID Data Tracker; MMWR; Pediatric RSV/COVID-19/Flu hospitalization surveillance. The interpretation of pediatric COVID-19 vaccine effectiveness requires careful attention to variant evolution, waning immunity, and the high background seroprevalence from prior infection — all of which make current VE estimates lower than the >90% efficacy observed in the original trials against ancestral strains.

Current Context

Protection against severe disease: COVID-19 vaccination continues to provide protection against hospitalization and death in children, though effectiveness wanes over 4–6 months and is partially restored by updated formulations. Pediatric ICU studies consistently show that the majority of critically ill children with COVID-19 are unvaccinated.
Protection against infection: Effectiveness against symptomatic SARS-CoV-2 infection with Omicron sublineages is modest (~20–40%) and short-lived (2–4 months for infection, somewhat longer for severe disease). This is a marked contrast to the >90% efficacy against original strains.
Pediatric vaccination coverage: As of 2024, U.S. pediatric COVID-19 vaccination coverage is substantially lower than for other childhood vaccines. Approximately 40–60% of adolescents and 10–20% of children under 5 have completed a primary series. Updated booster coverage is even lower.

Disease Burden Over Time

Reported U.S. disease burden by year. The dashed vertical line marks vaccine introduction. Hover or tap data points for values; use arrow keys when a chart has focus.

ⓘ About these charts: These are accessible SVG line charts with keyboard navigation, hover tooltips, and an underlying data table (expand below). The dashed vertical line marks the year of vaccine introduction. Reported cases undercount true incidence; case definitions, reporting practices, and diagnostic methods have changed over time. See Section 5 for additional context and pre-vs-post era comparisons.

7. Evidence Summary — Overall Assessment

Quality and Quantity of Safety Data

The COVID-19 vaccine safety evidence base is the largest in global public health history. More than 675 million doses have been administered in the U.S., and active surveillance through VSD and passive surveillance through VAERS span nearly 5 years. The evidence base includes:

Large randomized clinical trials (Pfizer adult N=~44,000; Moderna adult N=~30,000; multiple pediatric trials).
Active surveillance (VSD) covering ~9–10 million persons annually with near-real-time rapid cycle analyses specifically designed for COVID-19 vaccines.
Passive surveillance (VAERS) with >1.5 million reports — the largest safety database for any medical product in history.
International surveillance networks (GACVS, EudraVigilance, multiple national registries).
Targeted epidemiological studies addressing specific safety concerns (myocarditis, TTS/VITT, pregnancy outcomes, menstrual changes).

Areas Where Data Are Robust

Myocarditis risk (mRNA): The association is well-characterized by age, sex, dose, and product. The clinical course is well-described, though long-term cardiac outcomes are still being studied.
Acute reactogenicity: Rates of common adverse reactions (injection site pain, fatigue, headache, fever) are precisely characterized across age groups.
Absence of TTS/VITT with mRNA vaccines: Extensive surveillance has established that TTS/VITT is specific to the adenoviral vector platform and is not associated with mRNA vaccines.
Absence of GBS with mRNA vaccines: Large VSD and international studies are consistent in finding no association.
Pregnancy safety: Multiple large, independent datasets are consistent in finding no increased risk of adverse pregnancy outcomes.
Absence of infertility association: Multiple studies across several countries are concordant.

Areas Where Data Are Limited or Conflicting

Long-term (>5 years) safety outcomes: COVID-19 vaccines have been in use since December 2020. Follow-up beyond 5 years is not available. This is inherent to the recency of licensure and is not a deficiency specific to these vaccines. Theoretical concerns about long-term effects cannot be definitively addressed until sufficient time has elapsed, though the biological mechanisms of mRNA vaccines (rapid mRNA degradation, transient protein expression) do not suggest plausible long-term adverse effect mechanisms.
Myocarditis long-term cardiac outcomes: Five-year follow-up data on cardiac function post-vaccine-associated myocarditis in adolescents are not yet available. Preliminary 1–2 year data are generally reassuring, but the evidence is still evolving.
Effectiveness against current variants: The rapid evolution of SARS-CoV-2 means that efficacy data from the original pivotal trials are not applicable to current variants. All current effectiveness estimates are observational and subject to confounding (prior infection, waning, variant differences).
Updated vaccine formulations: Each updated formulation (BA.4/5 bivalent, XBB.1.5 monovalent, JN.1/KP.2 monovalent) undergoes more limited pre-licensure testing than the original products, relying on immunobridging and manufacturing process consistency. This is standard for strain-change vaccines (similar to influenza) but limits the pre-licensure safety database for each new formulation.
Very long-term effects in young children: The youngest vaccinated cohort (6 months–4 years) has the shortest post-licensure follow-up. Data on safety outcomes in this age group are necessarily less extensive than for older children and adults.

Overall Summary Table

Domain	Evidence Grade	Key Finding
Prevention of severe COVID-19 (children)	Strong	VE against hospitalization ~40–70% during Omicron; wanes without updated doses
Prevention of MIS-C	Strong	>80–90% reduction; MIS-C now rare
Prevention of symptomatic infection (Omicron)	Moderate	~20–40% short-term; limited durability
Myocarditis (mRNA)	Strong	~2–10 per 100,000 in males 12–17; generally mild clinical course
Anaphylaxis	Strong	~2–5 per million doses
TTS/VITT (mRNA vaccines)	No Association	Specific to adenoviral vector vaccines (Janssen)
GBS (mRNA vaccines)	No Association	Extensive VSD and international data; no signal
Infertility	No Association	Multiple large studies; no evidence
Adverse pregnancy outcomes	No Association	Multiple large studies; no increased risk
Long-term (>5 year) safety	Limited	Insufficient follow-up time; inherent to recency

8. International Surveillance & Global Data

Quick links to public pharmacovigilance databases and trial registries relevant to COVID-19 Vaccine. Reporting counts do not establish causality.

Note: Spontaneous reports are unverified observations. Compare with epidemiological studies in Sections 3–6 before drawing conclusions.

9. Curated Adverse Event Literature

Curated peer-reviewed literature linking specific adverse events to COVID-19 Vaccine. Each entry is a case report, case series, or related safety publication identified via PubMed. Expand Search PubMed for additional literature below to run custom queries.

Disclaimer: Published reports describe observations and associations; they do not establish population incidence or causality.

10. Key References

Polack FP, Thomas SJ, Kitchin N, et al. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med. 2020;383(27):2603–2615. DOI: 10.1056/NEJMoa2034577 (Pfizer adult pivotal trial, N=43,448)
Baden LR, El Sahly HM, Essink B, et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N Engl J Med. 2021;384(5):403–416. DOI: 10.1056/NEJMoa2035389 (Moderna adult pivotal trial, N=30,420)
Frenck RW Jr, Klein NP, Kitchin N, et al. Safety, immunogenicity, and efficacy of the BNT162b2 Covid-19 vaccine in adolescents. N Engl J Med. 2021;385(3):239–250. DOI: 10.1056/NEJMoa2107456 (Pfizer 12–15 trial)
Walter EB, Talaat KR, Sabharwal C, et al. Evaluation of the BNT162b2 Covid-19 vaccine in children 5 to 11 years of age. N Engl J Med. 2022;386(1):35–46. DOI: 10.1056/NEJMoa2116298
Oster ME, Shay DK, Su JR, et al. Myocarditis cases reported after mRNA-based COVID-19 vaccination in the US from December 2020 to August 2021. JAMA. 2022;327(4):331–340. DOI: 10.1001/jama.2021.24110
Goddard K, Lewis N, Fireman B, et al. Risk of febrile seizures after co-administration of COVID-19 and influenza vaccines in children. Pediatrics. 2023 (VSD study).
Shimabukuro TT, Nguyen M, Martin D, DeStefano F. Safety monitoring in the Vaccine Adverse Event Reporting System (VAERS). Vaccine. 2015;33(36):4398–4405. (Describes VAERS methodology)
See I, Su JR, Lale A, et al. US case reports of cerebral venous sinus thrombosis with thrombocytopenia after Ad26.COV2.S vaccination. JAMA. 2021;325(24):2448–2456. (TTS/VITT with Janssen) DOI: 10.1001/jama.2021.7517
CDC. COVID-19 Vaccine Safety Technical Reports (VaST). cdc.gov/vaccine-safety-systems/covid-19
CDC. VSD. cdc.gov/vaccine-safety/about/vsd.html
CDC/FDA. VAERS. vaers.hhs.gov
CDC. 2025 Child & Adolescent Immunization Schedule. cdc.gov/vaccines/hcp/imz-schedules

Vaccine Injury Compensation Overview

How to Access Compensation

COVID-19 vaccine injuries are covered under the CICP (Countermeasures Injury Compensation Program), which has different rules than the traditional VICP (Vaccine Injury Compensation Program).

Filing deadline: 1 year from vaccination date (strict)
Coverage: Reasonable medical treatment costs only (no pain/suffering damages)
Appeal: HHS Secretary only (no federal court available)
Attorney fees: Not covered by program

Overall Approval Rate

1.8%

137 of 7,542 claims eligible for compensation

Context: 49% of claims still pending. Rates provisional until final decisions made.

Procedural Denials

78.6%

5,820 claims denied for procedural reasons

Breakdown: 2,632 missed deadline | 2,772 missing records | 416 non-covered

How Claims Are Decided

7,542

Filed

→

5,820

Procedural Denials

→

1,585

Merit Denied

→

137

Approved

7,214 claims still pending decision (not shown). View detailed Sankey diagram →

Important Limitations

Approval ≠ Causation: Being approved for compensation does not mean the vaccine caused your injury. CICP has lower evidentiary bar than VICP causality table.
Pending backlog: 49% of claims still await decision. Final approval rates will shift as backlog is cleared.
Procedural barriers: 2,632 claims (35% of denials) rejected for missed deadline alone—no extension available.
Settlement mechanism: Some approvals may come from settlement/negotiation, not causality finding.
No federal court appeals: Unlike VICP, CICP claims cannot be appealed to U.S. Court of Federal Claims.

Which Program Covers My Vaccine?

Interactive tool to determine eligibility and filing requirements based on your vaccine and injury timeline.

Launch Program Router

COVID-19 Vaccine Injury Claims: Processing Timeline & Statistics

Total Claims Filed

7,542

Since December 2020

Decisions Made

7,542

100.0% of filings

Approved

137

1.8% approval rate

Pending Decision

7,214

95.7% awaiting review

Expected Processing Timeline

Processing rate: 88 claims/month

Current average throughput (2024-2026)

For 7,214 Pending Claims:

At current processing rate, pending claims will likely be resolved within 6.8 years (81 months).

Note: This is an estimate. Processing speed varies by case complexity and available resources.

Processing Bottlenecks

Procedural Denials: 78.6%

5,820 claims rejected for missing records, missed deadline, or non-covered product (not merit-based)

1-Year Filing Deadline

2,632 claims (~35%) denied for filing late. Strict deadline, no extensions.

49% Still Pending

7,214 claims awaiting decision. Timeline uncertain; rates are provisional.

Claims by Status (CICP COVID-19)

Status	Count	% of Total	Timeline Impact
Approved for Compensation	137	1.8%	Average 4-6 years from filing
Denied on Merits	1,585	21.0%	Substantial review required
Denied (Procedural)	5,820	77.0%	Faster (administrative only)
Pending Decision	7,214	48.9%	Est. 6.8 more years

⚠ Critical Information About Timelines

1-Year Strict Deadline: Claims must be filed within 1 year of vaccination. Missing this deadline results in immediate procedural denial—no exceptions.
Processing Delays: Missing medical records or incomplete documentation significantly delays claims. Gather evidence early.
Limited Appeal Rights: CICP appeals only go to HHS Secretary, not federal court. Unlike VICP (traditional vaccines), there is no federal court option.
Provisional Rates: With 49% of claims still pending, final approval rates will shift. These figures are not final.
No Pain/Suffering Damages: CICP covers reasonable treatment costs only. Does not include pain/suffering compensation like VICP.

Data source: HRSA CICP Data (April 1, 2026) | For real-time status: File or check claim at HRSA CICP

Time Window	VAERS		V-SAFE
0-6 days	3.7%	n=3	4.2%	n=12
7-14 days	66.7%	n=54	65.9%	n=189
15-30 days	24.7%	n=20	25.4%	n=73
31-60 days	4.9%	n=4	4.5%	n=13

Time Window	VAERS		V-SAFE
0-1 days	8.2%	n=187	12.1%	n=542
2-3 days	36.1%	n=823	32.4%	n=1456
4-7 days	42.3%	n=962	39.9%	n=1789
8-14 days	8.3%	n=189	8.9%	n=401
15-30 days	5.0%	n=113	7.2%	n=323

Time Window	VAERS		V-SAFE
0-1 days	9.1%	n=18	11.2%	n=67
2-3 days	39.4%	n=78	39.1%	n=234
4-7 days	36.4%	n=72	33.1%	n=198
8-14 days	11.1%	n=22	12.0%	n=72
15-30 days	4.0%	n=8	4.7%	n=28

Time Window	VAERS		V-SAFE
0-3 days	2.0%	n=2	3.1%	n=8
4-7 days	34.0%	n=34	43.1%	n=112
8-14 days	52.0%	n=52	45.8%	n=119
15-30 days	12.0%	n=12	8.1%	n=21