Above 15 human H5N1 cases in the United States during 2026

30-day trend

Analysis

This contract resolves to 'yes' if 15 or more confirmed human H5N1 cases are reported in the United States during 2026. The 15% probability reflects that such an outbreak would represent a significant escalation from recent years. H5N1 cases in the U.S. have been sporadic, with most occurrences limited to agricultural workers with direct animal exposure. The probability depends primarily on two factors: whether the virus continues spreading in U.S. livestock populations (particularly dairy cattle) and whether human-to-animal transmission rates increase or human-to-human transmission emerges. As of mid-2026, actual case data through the year will provide the primary signals for resolution. The contract's value chain shows declining probabilities at higher thresholds—above 10 cases trades at 6% and above 15 at 3%—suggesting market participants view sustained human transmission as unlikely but not impossible. Seasonal patterns and ongoing surveillance will shape how certainty evolves through the remainder of 2026.

• ›Current confirmed U.S. H5N1 cases in humans through May 2026 compared to historical annual totals (typically 0-3 cases annually before 2024)
• ›Extent of H5N1 circulation in U.S. livestock, particularly dairy herds, as a prerequisite for human exposures
• ›Evidence of human-to-human transmission capability, as nearly all historical U.S. cases involved direct animal contact
• ›Laboratory testing and reporting capacity across states to detect and confirm cases
• ›Seasonal transmission patterns, particularly during fall/winter months when influenza activity typically increases

What moved the line

• May 22Above 5↓5pp23→18¢ · Kalshi
• May 21Above 15↑4pp4→8¢ · Kalshi

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These markets stopped trading. Last odds and any captured outcome are shown above — full settlement detail lives at the venue.

How we compute these odds