HIV Risk Report
~PROPRIETARY BAYESIAN RISK MODELING ENGINE~
🕓 Model last updated: 1 November 2026
HIV Risk Report takes a fundamentally different approach to HIV risk estimation. The CDC's HIV Risk Estimator calculates transmission probabilities assuming one partner is already HIV-positive. Our proprietary Bayesian-inspired risk engine goes a step further by also estimating the probability that your partner had HIV in the first place. Using country-level epidemiological data, partner characteristics, exposure-specific transmission rates, condom use, PrEP, treatment status and biological modifiers, our engine combines these factors into a personalized statistical estimate of your actual encounter. Rather than simply presenting the risk of transmission from a known HIV-positive partner, we estimate the probability of HIV acquisition based on the circumstances you report, expressed as both a percentage and a "1 in X" figure. Your results are delivered in a comprehensive 6-page PDF report, including a detailed calculation breakdown, scientific context, and personalized HIV testing timelines.
Proprietary Bayesian analysis using encounter-specific data. Not a generic questionnaire.
WHY THIS ISN'T JUST ANOTHER HIV CALCULATOR
Most HIV risk tools ask a few questions and return a vague label. HIV Risk Report is fundamentally different. You don't just get a number. You get a 6-page personalized analysis that walks you through the entire calculation, explains what drove your result and gives you clear next steps.
Behind the report is our proprietary engine, which uses Bayesian probability modeling. Bayesian methods are widely used across medical and epidemiological research. Our engine applies this framework to calculate a personalized transmission probability for your scenario.
The model is regularly reviewed and updated as relevant new evidence becomes available. Model assumptions, epidemiological datasets and risk modifiers are regularly reviewed against the relevant published evidence. This isn't a static lookup table. It's a living statistical system.
Our methodology sits at the intersection of established HIV science and emerging AI-assisted health analysis, allowing evidence to be applied with greater context and specificity.
How the Engine Processes Your Data
Your inputs flow through a multi-stage Bayesian pipeline. Each stage updates the probability based on a new piece of evidence.
Inside the Bayesian Risk Engine
The system processes your encounter through multiple statistical layers. Each factor is a node in the calculation pipeline.
Exposure Type
Anal, vaginal and oral exposure each carry different baseline transmission probabilities, further split by insertive vs. receptive role.
Partner Probability
Country-level prevalence, partner demographics and risk indicators construct the Bayesian prior for the encounter.
ART Cascade
Treatment coverage and viral suppression rates are modeled using country-specific data to filter transmission probability.
Protective Measures
Condom use and PrEP are applied as risk-reducing multipliers derived from clinical trial data.
Biological Modifiers
Ejaculation, mucosal integrity, circumcision status and inflammation, each calibrated against peer-reviewed evidence.
Country Epidemiology
Country-specific HIV prevalence and treatment data contextualize your estimate within the relevant epidemic profile.
Understanding Our Methodology
Explore the scientific research, statistical models, and assumptions behind your personalized HIV risk estimate.
Probability-Based Modeling
Our engine combines published HIV transmission estimates with statistical assumptions about partner HIV prevalence and encounter-specific factors to produce an individualized risk estimate.
Research-Informed Approach
Our methodology draws on published scientific research, epidemiological statistics, and established HIV prevention data. Estimates depend on the available evidence and underlying modeling assumptions.
Transparent Calculations
Understand the inputs, assumptions, and mathematical factors contributing to your estimate. Explore our Risk Engine methodology .
Encounter-Specific Analysis
Your estimate considers the circumstances you report, including exposure type, geographical factors, condom use, and relevant HIV prevention measures.
Important: HIV Risk Report provides educational statistical estimates, not clinical diagnoses or individually validated predictions. Results are subject to uncertainty and should not replace HIV testing or advice from a qualified healthcare professional.
CDC HIV Risk Estimator vs. HIV Risk Report
Both approaches use published HIV transmission research, but they answer different questions. The CDC estimates transmission risk assuming one partner has HIV. HIV Risk Report goes a step further by also estimating the probability that a partner with unknown HIV status has HIV in the first place.
CDC HIV Risk Estimator
- Assumes one partner is HIV-positive and the other is HIV-negative
- Estimates transmission risk for individual sexual activities
- Provides numerical estimates per 10,000 exposures
- Accounts for condoms, PrEP, ART and certain additional risk factors
- Does not calculate the probability that a partner of unknown status has HIV
- Does not incorporate geographical HIV prevalence into its transmission estimates
HIV Risk Report
- Estimates the probability that your partner has HIV when their status is unknown
- Incorporates country-level epidemiological data and reported partner characteristics
- Combines estimated partner HIV probability with exposure-specific transmission statistics
- Considers relevant factors including condom use, PrEP and treatment-related protection
- Provides a personalized statistical estimate as a percentage and "1 in X" figure
- Explains the calculation inputs, assumptions and modeled risk factors
- Delivers a comprehensive 6-page PDF report with scientific context and testing timelines
Important: HIV Risk Report provides educational, model-based statistical estimates rather than clinically validated predictions of individual infection. Estimates depend on population data, reported information and modeling assumptions. Neither approach can determine HIV status or replace HIV testing.
Proprietary Bayesian analysis. 6-page personalized report. Full calculation transparency.
HIV Risk Calculator Resources
Learn more about how our Bayesian engine works, what factors influence HIV transmission probability and how to interpret your results.
Latest Risk Engine Update
The Bayesian model is regularly reviewed and refined as new evidence, methodology improvements and report functionality evolve.
VERSION 6.7
- Evidence Audit of Risk Multipliers: All risk multipliers in the Bayesian framework were cross-referenced against the supporting peer-reviewed evidence used by the model.
- Wound and Inflammation Adjustment: The applicable modifier was fine-tuned to better reflect published meta-analytic evidence.
- Circumcision Factor Update: Circumcision logic was harmonized across relevant exposure pathways where the same biological mechanism applies.
- On-Demand PrEP Calibration: The protection assumption for on-demand PrEP was adjusted to more closely reflect the IPERGAY evidence used by the model.
- Multiple Partner Factor: The applicable partner-risk modifier was recalibrated against supporting epidemiological literature.
- Intravenous Drug Use Logic: Partner-risk handling was reorganized within the formula to improve mathematical clarity and transparency.
- Expanded Source Citations: Additional peer-reviewed sources were added directly to the report reference section.