How the contract works
A contract on this market settles at $1 if the CDC's official Measles (Rubeola) counter shows 5,000 or more confirmed US cases for calendar year 2026, and at $0 if it does not. Settlement is based solely on the CDC's figures at cdc.gov/measles/data-research, not on state health department tallies or news reports, which can run higher or lower before CDC verification. The question resolves after the calendar year closes, with the resolution date set at 1 January 2027. The price at any given time reflects what buyers and sellers currently think the chance is; a contract trading at 0.30, for example, would imply the market sees roughly a three-in-ten chance of reaching that threshold. Positions can typically be sold before settlement at whatever price the market offers at that time, rather than held to the resolution date.
Yes69%
No31%
Probability
How the price has moved
The available data shows a consensus of 69% across the one venue currently trading this question, Polymarket, on volume of $287,182. No breakdown of the price's movement over the past day or week, or its range since the market opened, has been reported here, so the specific trajectory that produced today's level cannot be described with confidence. What can be said is that a single-venue market at this size reflects a moderate but not deeply liquid pool of opinion, meaning the price can be sensitive to comparatively small trades and should be read as an approximation rather than a tightly settled consensus.
Analysis
Context
The United States declared measles eliminated in 2000, meaning the virus no longer circulated continuously within the country; any cases since then have come from importation, mostly by unvaccinated travelers. That status held for nearly 25 years until an outbreak centered on under-vaccinated Mennonite communities in West Texas, spreading into New Mexico and neighboring states, took hold in early 2025. By spring 2025 the case count for that single outbreak had already surpassed the 1,274 cases recorded in all of 2019, itself the previous worst year since elimination.
The CDC tracks confirmed cases nationally through its Measles (Rubeola) data page, updated weekly with state-by-state and outbreak-linked breakdowns. Public health officials have watched closely for whether the chain of transmission from the 2025 outbreak would run past 12 continuous months, a technical threshold that would formally end the country's elimination status. That anniversary falls in early 2026, which is part of why the case count for calendar year 2026 itself has become a distinct question worth tracking, separate from the 2025 total.
Underlying vaccination rates are the structural driver behind all of this. MMR vaccination coverage among kindergartners has slipped below the 95% level considered necessary for herd immunity in a growing number of states and counties, particularly where religious or philosophical exemptions have expanded. That gap creates pockets where a single imported case can seed a large chain of transmission, which is what happened in Texas in 2025.
The consensus figure of 69%, drawn from $287,182 in trading volume concentrated on Polymarket, reflects a market that sees a 5,000-case year as more likely than not but far from certain. That level has to be read against the scale of what already happened in 2025: the West Texas-New Mexico outbreak alone pushed past the 1,274 cases recorded in 2019, which had stood as the worst year since national elimination in 2000. A 5,000-case threshold for 2026 alone is roughly four times that former record, which is a high bar in absolute terms, but not an unreasonable one if the same transmission chains, or new ones seeded by the same under-vaccinated communities, continue running through the year.
The key mechanical fact is that CDC counts are cumulative and confirmed, not projected. Every case has to go through state and local health department verification before it lands on the national counter, which introduces reporting lag but also means the number is not inflated by unconfirmed reports. Given that 2025 case totals were already elevated for most of the year, the question for 2026 turns on whether transmission chains active at year-end 2025 persist, and whether new clusters emerge in states with falling MMR coverage, such as Texas and Idaho, where kindergarten vaccination rates have dropped below the 95% herd-immunity benchmark in various counties.
A second factor is the elimination-status question itself. If the outbreak chain that began in early 2025 runs continuously past its 12-month mark into 2026, the CDC would be expected to formally note the loss of elimination status, a designation the country held since 2000. That kind of announcement tends to increase public and clinical attention to case counting and outbreak response, which can itself affect how quickly and completely cases are reported and confirmed, feeding into the 2026 figures the market is pricing.
The fact that trading is concentrated on a single venue, Polymarket, with a five-figure but not deep volume, means the price is likely to move on relatively modest trading activity, and should be read as an approximation of collective expectation rather than a tightly arbitraged consensus across many independent pools of money.
What moves the probability
Persistence of the 2025 outbreak chain
If the transmission chain rooted in West Texas and New Mexico continues into 2026 rather than burning out, cumulative cases build on an already-elevated base, pushing the probability of hitting 5,000 upward. A confirmed break in that chain by early 2026 would work against reaching the threshold.
Vaccination coverage in under-vaccinated counties
Kindergarten MMR coverage below the 95% herd-immunity level in parts of Texas, Idaho and other states creates the conditions for large outbreaks from single imported cases. Any state-level push to close exemption loopholes or run catch-up vaccination campaigns would reduce the odds of reaching 5,000.
Formal loss of elimination status
Should CDC confirm that continuous transmission has run past 12 months, the resulting scrutiny and case-finding effort could itself increase the confirmed case count for 2026, since more testing and follow-up typically means more confirmed cases identified.
International importation and travel season
Measles is far more prevalent globally than in the US, and imported cases linked to international travel, especially around school terms and holiday travel periods, have historically seeded new domestic clusters. A rise in international case exportation to the US would push the count higher.
Public health response effectiveness
Targeted vaccination campaigns and rapid outbreak containment in affected communities, as seen in parts of the 2025 response, can shorten chains of transmission and cap case totals well below worst-case trajectories.
The case for
- The transmission chain active in Texas and New Mexico through 2025 continues without a confirmed 12-month gap, keeping the outbreak legally and epidemiologically active into 2026.
- MMR vaccination coverage in several counties remains below the 95% threshold needed for herd immunity, leaving room for large clusters from single imported cases.
- Continued international travel-linked introductions seed new clusters in additional states beyond the original outbreak area.
- A formal CDC announcement on elimination status increases surveillance and case-finding, raising the confirmed count faster than in a lower-scrutiny year.
The case against
- Even the historically severe 2025 outbreak, the worst since 2000, would need to be roughly matched or exceeded again in 2026 alone to cross 5,000, a bar no year has approached in the elimination era.
- Targeted vaccination catch-up campaigns and containment measures in the affected Texas and New Mexico communities could break the transmission chain before the 12-month elimination-status threshold is reached.
- CDC verification requirements mean unconfirmed or state-reported cases do not count until reviewed, which can slow the pace at which the national counter climbs regardless of on-the-ground spread.
- A shift in public attention and resources toward vaccination promotion following the 2025 outbreak could suppress new clusters before they scale.
What to watch
The CDC's weekly Measles (Rubeola) data updates at cdc.gov/measles/data-research are the primary source to track, since they are the only figures that count toward settlement. Watch for any formal CDC statement on the loss of US measles elimination status, expected around the point the West Texas-New Mexico outbreak chain crosses 12 months of continuous transmission in early 2026. State-level vaccination exemption data released ahead of the 2026-27 school year, and any new outbreak clusters reported outside the original affected states, will also shape the trajectory toward or away from the 5,000-case threshold.
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