What will the average number of measles cases be during Trump's term?

**Stage 1 — Blind analysis (ignore current market price):**

- *Data anchor:* The clearest hard data point is CDC’s report of **1,983 confirmed U.S. measles cases as of May 28, 2026**, reported from **40 jurisdictions**, with large local outbreaks (e.g., Utah at 663 cases). Measles is highly transmissible and outbreak sizes are fat‑tailed: a few big outbreaks account for most cases in any given year.

- *Mechanics and epidemiology:* Because measles incidence is dominated by sporadic, concentrated outbreaks, a single very large outbreak (or two) during a four‑year window will materially raise the 4‑year average. If 2026 finishes near or above 2,500–3,000 cases (plausible given the YTD pace), that single year lifts a four‑year average substantially even if other years are lower. Social/behavioral drivers (vaccine hesitancy, policy changes, cross‑state clusters) and importations make repeat large outbreaks plausible over a multi‑year span.

- *Counterforces:* Public‑health responses (intensive outbreak control, ring vaccination, catch‑up campaigns) can blunt and shorten outbreaks. Large outbreaks also deplete the local susceptible pool (temporarily), and heightened public concern typically raises vaccine uptake during/after high‑visibility outbreaks. These effects can reduce cases in subsequent years.

- *Synthesis and independent probability:* Weighing the very high early‑2026 count, the broad geographic spread, and the high variance of measles outcomes, I judge it more likely than not that the 2025–2028 average will be in the elevated regime that market participants label as "Yes." Concretely: **72% independent probability** that the average during the Trump administration meets the market’s 'Yes' condition (see caveat about ambiguity below).

**Stage 2 — Market calibration (compare to market prices and explain differences):**

- *Market state:* Current market prices show **Yes: 0.32 / No: 0.68** (i.e., the market treats the 'Yes' outcome as unlikely). My independent 72% estimate is materially higher than the market price.

- *Why the market might be pricing 'Yes' lower than my estimate:* - **Ambiguity in the market question.** The event statement does not specify the numerical threshold or the averaging method (e.g., arithmetic annual average over 2025–2028, median, or a bin cutoff). Traders unsure what 'Yes' means will trade conservatively and push probability toward 0.5 or the side they intuitively believe is less extreme. If the market's 'Yes' means a *very* high threshold (e.g., average > 2,000–3,000), the market price of 0.32 could be rational. I have assumed a more moderate elevated threshold consistent with the provided context. If my interpretation of the threshold is wrong, that can explain most of the divergence. - **Risk‑averse/contrarian liquidity providers.** Some traders may be selling 'Yes' because they expect aggressive public health responses or they prefer to take the other side when news is noisy. Large volume (146,923 contracts) suggests active trading; short‑term liquidity and hedging can depress the 'Yes' price below a fundamental view. - **Recency skepticism.** Market participants can underweight a single-year spike (even one as large as 2026) because they expect regression to the mean in later years; this bias would lower 'Yes' probability versus my view.

- *Conclusion on calibration:* I believe the market is **undervaluing** the chance of a sustained elevated average because: (a) the 2026 YTD count is already very large and geographically broad; (b) measles dynamics are fat‑tailed so one or two big outbreaks in a four‑year window are sufficient to produce an elevated average; and (c) policy and social trends in 2024–2026 have increased susceptibility pockets. However, if the market’s 'Yes' condition is a much higher numerical threshold than I assumed, the market price might be reasonable — this is the central ambiguity that should be resolved before trading.