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

**Stage 1 — Blind analysis (ignore market prices)**

Assumption declared up front: *I take the binary proposition "Yes" to mean the average annual number of confirmed U.S. measles cases across 2025–2028 is ≥1,000 ("in the thousands").* This is the natural reading of the prompt and the news summary referring to an average "in the thousands." If the market uses a different numeric threshold, probabilities should be re-estimated to match.

Detailed factual context and reasoning:

- The U.S. has recorded a record-high measles year in 2025 and, as of June 25, 2026, already has **2,134 confirmed cases** in 2026 with cases in **41 states**. Through mid-year 2026 the outbreak is already larger than 2025’s total, which implies a high baseline for the multi-year average. 2025 ↗ 2026 indicates a recent upward trend rather than a one-off blip.

- The main structural drivers pushing case counts upward are clear: **lower childhood vaccination rates** in many communities, clusters of unvaccinated or under-vaccinated populations, and politicized/uneven vaccine access and uptake. Measles is highly transmissible (R0 well above many other childhood diseases) so even relatively small pockets of susceptibility can sustain sizable chains of transmission and repeatedly seed outbreaks.

- Public-health countermeasures (surge response, targeted MMR campaigns, school exclusion policies, strengthened surveillance) can and do reduce spread, but they often operate reactively. Large outbreaks increase short-term immunity in affected cohorts (reducing susceptibility locally) but also reveal weaknesses in routine immunization programs that are slow to correct nationwide.

- Seasonal and stochastic factors matter: measles transmission can vary by season and by highly local superspreading events (schools, religious communities, travel). Given current widespread multi-state transmission, it is plausible outbreaks will occur repeatedly across multiple years rather than being confined to a single year.

Synthesis and quantitative judgment:

- Given that 2025 was already record-high and 2026 is on pace to surpass it, plausible multi-year averages hinge mainly on whether 2027–2028 see dramatic improvement in vaccination coverage and faster suppression of transmission. Historical precedent: when vaccination coverage falls and measles re-enters communities, outbreaks commonly persist for several years until coverage is restored.

- I estimate about a 72% chance that the 4-year average (2025–2028) ends up ≥1,000 per year. This reflects: current multi-thousand-year-to-date numbers in 2026, the scale and geographic breadth of outbreaks (41 states), slow correction of vaccination gaps, and the difficulty of galvanizing sustained, rapid nationwide increases in routine childhood coverage.

**Stage 2 — Market calibration (considering current market price Yes: 0.30)**

- The market price (Yes = 30%) is substantially below my independent estimate (72%). Possible reasons for the gap: - *Ambiguity/threshold mismatch:* Market participants may be interpreting the question differently (e.g., a higher numeric threshold such as ≥2,000 average per year rather than ≥1,000). If the contract’s threshold is unstated or different, that would explain a lower Yes price. - *Short-term optimism bias / belief in public-health intervention:* Some traders may overweight rapid therapeutic/public health responses or successful MMR catch-up campaigns that materially suppress 2027–2028 counts. That could justify a lower Yes probability but seems optimistic given recent trends. - *Liquidity, noise and political bettors:* Active volume (~148k contracts) suggests participation but doesn't guarantee correct pricing; political markets often attract bettors who anchor to narratives or partisan expectations rather than epidemiology. - *Time-discounting and risk aversion:* Traders may be implicitly giving extra weight to potential corrective actions (school mandates, emergency funding, targeted large-scale vaccination drives) that reduce multi-year averages, or they may be misreading the continuing risk of repeated outbreaks.

- My assessment is that the market is likely *underpricing* the probability that the 4-year average is ≥1,000 per year, *unless* the market is referencing a materially higher numeric threshold. If the threshold is indeed 1,000, I view the market price as a buying opportunity for Yes exposure; if the threshold is higher (e.g., 2,000 average), the market price may be more defensible.

- Practical calibration recommendation: confirm the contract’s numeric threshold. If it is 1,000, my model suggests that fair price should be closer to **0.70–0.75**, so market Yes = 0.30 looks undervalued. If threshold is 2,000+, the market may be reasonable.

(Notes: This entire analysis ignores rare exogenous shifts such as an immediate, very large-scale federal vaccination mandate, a novel long-lasting therapeutic that changes measles dynamics, or catastrophic breakdown of public-health reporting.)