About & Methodology
VaxFact.net uses a transparent, evidence-based scoring model to help parents and patients understand vaccine benefit-risk tradeoffs. Here's exactly how it works.
🎯 Our Mission
VaxFact.net was built on a simple premise: vaccine decisions deserve the same rigorous, transparent analysis that financial or medical professionals apply to other important choices. Parents shouldn't have to choose between uncritical acceptance and unfounded fear.
We present population-level evidence — the same data that public health agencies, pediatricians, and researchers use — organized in a way that helps individuals understand both the benefits and the real (if often tiny) risks of each vaccine.
We are pro-science and pro-transparency. That means acknowledging genuine scientific uncertainties and credible debates, not hiding them. True informed consent requires honest information.
📊 The Scoring Model
Each vaccine receives six computed scores on a 0–100 scale. The final “Net Benefit” score is a function of all six dimensions, weighted by your personalized scenario inputs.
Exposure Risk
Base rate × Age factor × Scenario multipliers × Community coverage factorHow likely is it that your child will encounter the pathogen? This accounts for daycare, travel, outbreak status, community vaccination rates, and age-specific vulnerability.
Disease Consequence
Σ(outcome probability × severity weight)How severe is the disease if acquired? We weight mortality, ICU admission, hospitalization, chronic sequelae, and quality-of-life loss using validated severity weights from the project's evidence model.
Vaccine Benefit
Weighted VE × Disease ConsequenceHow much does the vaccine reduce disease harm? Combines effectiveness against severe disease (50% weight), death (30%), and infection (20%).
Vaccine Harm
Σ(AE probability × severity weight) + Uncertainty penaltyThe risk from the vaccine itself. Sums all adverse events weighted by severity and probability, plus a penalty for evidence uncertainty.
Evidence Confidence
Composite of study quality, sample size, replication, and consensusHow certain is the evidence? Reflects years of study, trial quality, sample sizes, independent replication, and expert consensus.
Net Benefit
(Exposure Risk × Disease Consequence × Vaccine Benefit) / 10,000 − Vaccine Harm + 50The final score. Combines all dimensions into a single 0–100 number. Scores 75+ = strong recommendation; 55–74 = moderate; 35–54 = consider; <35 = discuss with provider.
🔬 Evidence Standards
We use a hierarchical evidence model. Studies are categorized by type and weighted by confidence level:
Randomized controlled trials and systematic reviews of multiple RCTs receive the highest confidence weight.
Large prospective cohort studies from CDC, WHO, and Vaccine Safety Datalink are used extensively.
VAERS and passive surveillance data are used for adverse event rates but are adjusted for underreporting bias.
ACIP, WHO SAGE, and GACVS advisory panel decisions are incorporated as consensus evidence.
Credible Critiques vs. Misinformation:We distinguish between legitimate scientific debates (published in peer-reviewed journals, debated by credentialed researchers) and misinformation (unsupported by credible evidence). Only the former appears in our “What Researchers Question” sections.
📂 Data Sources
Primary source for US vaccination schedule and recommendations
Global vaccination coverage, disease burden, and policy data
Large-scale US safety surveillance database
Passive US adverse event surveillance (adjusted for underreporting)
Independent systematic reviews of vaccine evidence
Peer-reviewed journal citations for individual vaccine data
Standardized adverse event definitions used in our severity scoring
Independent expert committee reviews of vaccine adverse effects (2012 landmark report and ongoing)
European vaccine approval and safety surveillance data
Smartphone-based health check-in system for COVID-19 and other vaccine safety monitoring
WHO's independent body reviewing vaccine safety signals worldwide
⚠️ Limitations
VaxFact.net is an educational tool with important limitations you should understand:
Scores are based on population-level data and may not reflect your child's individual health conditions.
Disease incidence figures represent US averages and may differ significantly in other countries or regions with active outbreaks.
Adverse event probabilities are estimates from surveillance systems that have known underreporting and attribution challenges.
Evidence changes over time — we update data periodically but cannot guarantee real-time accuracy.
The scoring model involves judgment calls in weighting different health outcomes. Reasonable experts may weigh them differently.
We do not account for all possible contraindications, drug interactions, or special medical circumstances.
📅 Data Updates & Changelog
VaxFact.net is updated as new evidence emerges. Major data changes are documented below.
Mpox (JYNNEOS), Cholera (Vaxchora/Shanchol), Japanese Encephalitis (Ixiaro), and Tdap adult booster added with full evidence profiles.
New side-by-side comparison table with net benefit, effectiveness, risk, and evidence scores for all 24 vaccines.
Added 20+ new questions across 4 new categories: Vaccine Ingredients & Manufacturing, Decision-Making for Parents, Community Immunity, and Monitoring Vaccine Safety.
Full mobile-responsive redesign: hamburger navigation, responsive grid layouts for all pages, touch-optimized interactions.
VaxFact.net launched with 20 vaccines, personalized benefit-risk calculator, outbreak map, vaccination timeline, and schedule page.
⚕️ Medical Disclaimer
VaxFact.net provides educational information only. This is NOT medical advice. All vaccine decisions should be made in consultation with a licensed healthcare provider who is familiar with your individual health history, your child's specific medical conditions, and current local epidemiology. Never delay or forgo vaccination based solely on information from this website. The content on VaxFact.net is for informational purposes and does not replace a physician-patient relationship.