As of June 11, 2026, the CDC has confirmed 2,073 measles cases in the United States for the year, already approaching the full-year 2025 total of 2,288, with 93% outbreak-associated across 40 jurisdictions and 30 new outbreaks reported. Low MMR vaccination coverage in specific communities—such as the large ongoing South Carolina and Utah clusters—drives sustained local transmission of this highly contagious virus (basic reproduction number typically 12–18), with 92% of cases unvaccinated or unknown status and most infections domestically acquired rather than imported. Weekly CDC surveillance updates and state health reports on case counts, hospitalizations, and new outbreaks remain key near-term catalysts for market movement, as continued weekly increments of 40–60 cases could push the annual total well above prior records before year-end.