The federal government shutdown has brought respiratory virus surveillance to a halt at the national level, leaving local governments, health systems and the general public with critical blind spots as the season starts to ramp up.

Key federal reports on flu, Covid-19 and RSV haven’t been updated in nearly a month, even as virus activity picks up.

These viruses kill tens of thousands of people in the US each year and hospitalize hundreds of thousands more, but they typically follow seasonal patterns and don’t spread as quickly as diseases like measles.

During a shutdown, national disease surveillance reports are updated only if they “protect from imminent loss of life,” said Dr. Caitlin Rivers, an epidemiologist and director of the Center for Outbreak Response Innovation at the Johns Hopkins Bloomberg School of Public Health.

The federal government’s measles response is an “active public health intervention” and permitted by law to continue, according to a statement from the US Department of Health and Human Services, but the shutdown “thwarts the CDC’s ability to continue to publish routine flu data from its public health partners”

The US Centers for Disease Control and Prevention’s general Respiratory Illness Data Channel – which offers insight into viral activity through trends in early warning signs like wastewater surveillance and emergency department visits – was last updated September 26, a few days before the shutdown began. Weekly updates from the more specific FluView have stopped, as have summary reports from RESP-NET that tracks hospitalizations for Covid-19, flu and RSV from a network of hospitals across the country.