Real-time measles surveillance from 700+ CDC monitoring sites during the 2025–2026 US resurgence
⚠ The US is experiencing a significant measles resurgence in 2025–2026. Wastewater surveillance is detecting measles RNA at sites across multiple states. If you are unvaccinated or unsure of your vaccination status, contact your healthcare provider.
The United States declared measles eliminated in 2000, but elimination does not mean eradicated — it means sustained domestic transmission was interrupted. When vaccination rates decline below the herd immunity threshold (approximately 95% for measles, one of the most contagious diseases known), pockets of vulnerability emerge, and imported cases can spark outbreaks.
The 2025–2026 measles season has seen outbreaks in multiple states, driven by declining MMR vaccination rates in some communities. Wastewater surveillance is now detecting measles RNA at monitoring sites across the country — providing an unprecedented real-time view of how broadly the virus is circulating.
Traditional measles surveillance relies on clinicians recognizing the distinctive rash and reporting cases. But measles is contagious for 4 days before the rash appears — meaning a person is spreading the virus before anyone knows they have measles. Wastewater surveillance can detect measles RNA in community sewage before cases are clinically identified, providing earlier warning of local transmission.
Measles wastewater surveillance is newer than COVID-19, flu, and RSV tracking. The CDC expanded NWSS measles monitoring in response to the 2024–2025 outbreak activity. Coverage is improving, but some gaps exist — particularly in rural areas.
Measles has a basic reproduction number (R0) of 12–18, meaning one infected person can spread it to 12–18 unvaccinated contacts. It spreads through the air and can survive on surfaces for up to 2 hours. If you are unvaccinated and enter a room where someone with measles has been, you have a 90% chance of becoming infected.
This extreme contagiousness is why the wastewater data deserves serious attention — even small detected signals can indicate meaningful community spread.
Measles begins with fever, cough, runny nose, and red eyes (conjunctivitis), followed by the characteristic red, blotchy rash that starts on the face and spreads downward. The illness typically lasts 7–10 days.
Complications are common and can be severe:
The MMR (measles-mumps-rubella) vaccine is one of the most effective vaccines ever developed. Two doses provide approximately 97% protection against measles. The vaccination schedule is:
If you are unsure whether you or your child are vaccinated, contact your healthcare provider. A blood test (titer test) can confirm immunity.
Measles wastewater data comes from the CDC NWSS. Because measles wastewater monitoring is newer than the other pathogens on this site, some monitoring sites have shorter historical records, and the percentile context may be less robust than for COVID-19 or flu. We display the data as available and note where coverage is limited.