90-Second Read: Polymarket’s Hot New Bet: Hantavirus

Medical professionals sail towards the cruise ship MV Hondius in response to a deadly outbreak of Hantavirus. AFP/Getty Over the past four days, bettors on the prediction platform Polymarket have wagered nearly $3 million on whether we'll see a Hantavirus pandemic this year. But Polymarket users are spending big across several Hantavirus-related propositions—including whether a vaccine will be developed this year and whether or not officials will tie the cruise ship outbreak to a "lab leak." Polymarket declined to comment on Hantavirus betting. Users have wagered nearly $3 million on the odds of a Hantavirus pandemic. A cluster of cases of a particularly deadly strain of the virus erupted on a cruise ship last month, killing three people out of eight suspected cases linked to the vessel.

Though the news has stoked fears, the World Health Organization currently classifies the risk of a full-blown pandemic as low. It spreads very, very differently." Because outbreaks of this Hantavirus strain have occurred before, infectious disease experts already know that the virus requires close contact to spread between people, and a person with the virus is only infectious for about a day. Now, on mega-platforms like Polymarket and Kashi, users can bet on almost anything—including public health crises. Online gambling has been on the rise since sports betting was legalized by the Supreme Court in 2018, but the Covid pandemic gave it a huge boost. But a 2024 court ruling took the rails off of websites known as prediction markets.

Just as those metrics allow public health officials to calibrate their response, they also inform how some online gamblers are placing their money. But there were other bets to be placed, like how many people would die from Covid-19, a topic some people wagered on as early as April 2020. Ayers, a public health professor at University of California, San Diego. That gambling is a public health issue in itself, Ayers says. This is not the start of a Covid pandemic," said Maria Van Kerkhove, director of epidemic and pandemic management at the WHO, at a Thursday press conference.

A study Ayers led that came out last year found that Google searches seeking help for gambling addiction jumped 23 percent nationwide since the legalization of sports betting. Platforms like Kalshi and Polymarket grow based on use, helping the range of niche bets to multiply—and since taking off during the Covid pandemic, the prediction-market industry has multiplied in size many times. In 2020, sports betting revenues jumped up 69 percent over the previous year, though not too many sports events were happening. Other researchers estimate about 10 percent of men ages 18 to 30 have a problematic relationship to gambling. By 2030, it's been estimated, prediction markets could grow to $1 trillion in annual trading volume.