Public health relies on data – whether it is tracking the effectiveness of a given year’s flu vaccine, monitoring blood lead levels around the country or estimating the prevalence of diabetes. This data forms the basis for decisions such as whether a community should expand screening for diabetes and which communities are at greatest risk of severe flu-related illnesses.

But in January 2025, at the beginning of President Donald Trump’s second term, webpages and data from the Centers for Disease Control and Prevention – and from many other federal agencies – began to disappear. In total, at least 200 CDC datasets and more than 8,000 webpages from across the government were taken down.

Though many of these resources were subsequently restored in the months that followed, the speed and scale of the removals make a full accounting difficult. Even now, more than a year after so much data from federal agencies was removed, researchers like me are discovering new mechanisms through which this same data remains at risk.

Most recently, for example, more than 6,000 webpages on energy conservation wwere removed from federal websites while a heat wave ravaged the U.S. through Fourth of July celebrations.

I am an infectious disease epidemiologist who studies how respiratory pathogens affect communities around the world and how data is used to monitors these impacts. Every day, health departments, practitioners and researchers have to make decisions on where to direct resources, which conditions to monitor and even which research questions to prioritize. Without high-quality data to support them, these decisions run the risk of becoming mere........

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