38% — Measles cases in U.S. by May 31?: 1925
Leader: 2000 at 38% · Polymarket 38% · 2 contracts · $10K volume · low confidence
Updated 2026-05-28 22:18:27 UTC

Tracks the leading outcome in a winner-take-all prediction market set with 2 outcomes.

Why this matters:
This market predicts whether U.S. measles cases will total 1,925 or fewer by May 31, 2026. The 96% probability reflects confidence that cases will remain below this threshold, with only 12 days remaining until resolution. Measles case counts depend on ongoing transmission rates, vaccination coverage, and outbreak containment efforts. The market assigns roughly equal probability (68–96%) to staying below 2,000 cases versus falling below 1,925, suggesting traders expect a relatively narrow final tally. Resolution occurs automatically on May 31 when CDC reports cumulative 2026 case data. Current momentum and the short timeframe suggest the outcome is largely determined by present transmission trends.

Key factors:
- CDC reported measles surveillance data through mid-May 2026 will indicate whether year-to-date cases have accelerated or plateaued relative to contract thresholds
- Vaccination rates and outbreak control measures in high-risk populations directly affect transmission velocity in the final 12 days
- Any large institutional or healthcare outbreak detected and reported before May 31 could push cumulative cases across the 1,925 threshold
- The 68¢ price on the 1,950-case contract implies traders see meaningful probability of the final count landing between 1,925 and 1,950
- Low trading volume ($35–$232 per contract in 24 hours) suggests limited liquidity and potential for price movements on new case reports

Contracts:
- Measles cases in U.S. by May 31?: 2000 — 38¢ Polymarket $7K (weight 72%)
- Measles cases in U.S. by May 31?: 2200 — 5¢ Polymarket $3K (weight 28%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-05-28T21:20:08.932Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "38% per prediction markets (SimpleFunctions, May 2026)"
Canonical: https://simplefunctions.dev/answer/measles-cases-us-may-31
Full data: https://simplefunctions.dev/api/public/query?q=Measles%20cases%20in%20U.S.%20by%20May%2031%3F%3A%201925
Provider: SimpleFunctions — https://simplefunctions.dev