Hantavirus Pandemic 2026

Hantavirus risk has kept fading. Polymarket's headline Hantavirus pandemic in 2026? trades at 2.6% on $3,130 of 24-hour volume and $1.21M of open interest, down from 3.65% three weeks ago. Kalshi's WHO Public Health Emergency of International Concern Single is 3.4%, down from 6%, on $2,400.

The inversion this page flagged in September holds on both venues. Polymarket and Kalshi each price a generic new pandemic in 2026 at 4.5%, above their hantavirus lines. The books rate the named pathogen as less likely than an unnamed one: the market is saying the MV Hondius cluster is contained.

With three months left in the year, every line here is also decaying toward its year-end settlement. This workspace keeps the headline Singles side by side, the origin question that is still open, and the broader 2026 pandemic-risk books that give the hantavirus number its context.

Polymarket's Hantavirus pandemic in 2026? at 2.6% paired with Kalshi's WHO PHEIC for hantavirus Single at 3.4%. Same story, two settlement primitives—pandemic definition against PHEIC declaration—which is most of why the Kalshi line sits higher. A PHEIC is a lower bar than a pandemic, and it is declared by a committee rather than triggered by case counts. The gap between them has narrowed from 2.35 points to 0.8.

The June 30 Polymarket outbreak and lab-leak checkpoints both settled No and have been retired. What remains of the forensic question lives on Manifold: whether the MV Hondius outbreak is traced to rats aboard the ship itself, now 8.2%, down a point since September and untraded today. Polymarket has not listed a replacement dated checkpoint, so this row runs half width by design rather than carrying a settled book.

Year-level pandemic questions without the hantavirus narrowing. Kalshi's Pandemic in 2026? and Polymarket's New pandemic in 2026? both price 4.5%, down from 5.5% and 6.5%. Kalshi's is the busiest book on the page today at $13,655; Polymarket's turned $115. Both sit above their venue's hantavirus line, so none of the pandemic pricing is attributable to this pathogen.

Manifold's mirror of the Polymarket pandemic Single reads 0.7% against Polymarket's 2.6%: the play-money book prices the same question at roughly a quarter the probability. The hantavirus-vaccine Single at 2.5%, down from 5.5%, is the asymmetric tail; it reprices on regulatory news rather than case counts and did not trade today.

• Hantavirus trades below generic pandemic risk on both venues. 2.6% against 4.5% on Polymarket, 3.4% against 4.5% on Kalshi. A move back above the generic line would be the first sign of renewed concern.
• The cross-exchange gap on the headline is definitional, and it has narrowed. Kalshi's WHO-declaration line sits 0.8 points above Polymarket's pandemic line, from 2.35 points in September.
• Time decay. Every book here settles at year end. With three months left and no new cluster, the lines drift down on their own.
• Manifold reads a quarter of Polymarket. The play-money mirror at 0.7% is the most bearish book in the workspace. Gaps this size on thin books usually reflect stale quotes rather than a view.
• The MV Hondius origin question is still open on Manifold at 8.2%.
• Volume. Kalshi's generic pandemic book turned $13,655; the hantavirus headline turned $3,130 on Polymarket, a tenth of September's $31,000. A price move on a few hundred dollars is noise.