Prediction Markets Now Take Bets on Measles Outbreaks, FDA Decisions, and Vaccine Mandates — Outside Every Gambling Safeguard

Polymarket and Kalshi host wagers on US health outcomes — measles cases, drug approvals, vaccine policy — while operating in a regulatory gap that exempts them from gambling oversight, consumer protections, and insider-trading rules.

Polymarket and Kalshi, the two dominant online prediction markets, now offer contracts on US public health outcomes. Users can bet on measles case counts for 2026, whether the US loses its measles-elimination status, when the FDA will approve a skin-cancer vaccine, and whether the CDC will alter its vaccine recommendations. Drug trial outcomes and approval timelines are also on the board. A Polymarket sign posted next to a Brooklyn elementary school advertised bets on whether any state would end vaccine mandates — a fact that tells you everything about the target audience.

The regulatory architecture is the story. Prediction markets classify themselves as financial derivatives, not gambling, which places them under the Commodity Futures Trading Commission rather than state gambling regulators. This is not a technicality — it is the entire business model. As Lia Nower, director of the Center for Gambling Studies at Rutgers, put it: prediction markets are "functionally identical" to regulated gambling but sit outside every consumer-protection framework designed to limit gambling harm. No deposit limits, no self-exclusion tools, no advertising restrictions, no state tax revenue flowing to treatment programs. Several states have filed lawsuits alleging the platforms function as gambling sites. The insider-trading risk is structural, not hypothetical. Matthew Eisenberg, professor and chair of health policy and management at Johns Hopkins, identified the core problem: predictions on FDA decisions and trial endpoints "create a payoff for anyone with nonpublic information" — agency reviewers, trial investigators, legislative staff. The risk, he said, is not necessarily that a reviewer takes a bribe but that "the market now rewards leaks." Advocates and lawmakers could place bets on ending vaccine mandates and then introduce legislation to make it happen; Nower confirmed there appear to be no laws against this. Kalshi's defense is revealing. Spokesperson Dani Lever argued that clinical trial markets would "improve transparency" because "the people who best know whether a trial will succeed are scattered, and their insight rarely reaches the public." This is a description of insider information repackaged as a public good. Polymarket did not respond to questions about public health consequences. The gambling harm dimension compounds the public health dimension. A new Rutgers report found that more than half of Americans aged 13 to 27 gambled in the past year; among young gamblers, 39.5% had some degree of gambling-related risk and 10.3% were high risk for problem gambling. Eisenberg's research found that legalization of online sports betting was followed by measurable increases in treatment for depression and anxiety among young men. States have begun building consumer protections around sports betting — deposit limits, self-exclusion, advertising rules, treatment funding from betting taxes — but prediction markets sit outside all of it. Eisenberg offered an important calibration: the public health contracts are small. "Prices that small can be moved by a single trader and shouldn't be read as public opinion," he said. "A few-hundred-dollar contract on the childhood vaccine schedule is not a forecast of anything." The markets are not yet large enough to distort outcomes at scale. But the infrastructure is being built, the regulatory gap is real, and the incentive structures point in one direction. Within a week of its posting, the Polymarket sign in Brooklyn was vandalized. Someone ripped away the bottom portion — the Polymarket logo and the betting prompt. What remained was a single word: "Vaccines." The public edited the ad into the public health message it was pretending to be.