The gaps in CDC's public health data are creating dangerous blind spots

The Centers for Disease Control and Prevention, known as the CDC, is the main U.S. agency that tracks health information across the country. Starting in January 2025, thousands of health data pages and datasets began disappearing from government websites. In all, at least 200 CDC datasets and more than 8,000 webpages were removed. Health experts say those gaps make it harder to protect people from diseases and other health dangers.

Public health workers depend on data every single day. They use it to track how well flu vaccines are working, to check blood lead levels in communities, and to figure out how many people have diseases like diabetes. When that data disappears or stops being updated, doctors, researchers, and health departments lose a key tool. As one expert put it, without good data, health decisions run the risk of becoming mere guesses.

Many of the removed pages were later brought back. But the removals happened so fast and on such a large scale that it is still hard to know exactly what was lost. Even more than a year later, researchers are finding new ways that important health data is still at risk. For example, more than 6,000 webpages about energy conservation were taken down during a dangerous heat wave over the Fourth of July holiday.

A study published in January 2026 found a troubling pattern. Among CDC datasets that used to be updated every month, nearly half — about 46% — had stopped being updated without any explanation. Most of those pauses, about 90%, involved data on vaccines or common respiratory viruses like the flu, COVID-19, and RSV. Respiratory viruses can cause serious illnesses like pneumonia, so losing track of that data is a big concern.

HIV data was also affected. The CDC stopped updating information on how many people have HIV and whether they know they are infected. The agency's own website blamed staff cuts for the pause. As of early July 2026, some of that HIV data had still not been updated, even though a note on the website said the CDC was working on it.

The CDC is part of a larger government department called Health and Human Services, or HHS. Starting in early 2025, HHS made deep cuts to its staff, which hurt the CDC's ability to collect and share health data. Some CDC data is open for anyone to read online, but other sensitive data requires researchers to apply and be approved before they can see it. When the staff members who handle those approvals are fired, no one can get to the data — even if it still exists.

That is exactly what happened with a program called the Pregnancy Risk Assessment and Monitoring System, the gold standard for data on the health of mothers and babies in the U.S. In January 2025, the CDC quietly stopped processing requests to access that data, and on April 1 the whole team running the program was let go. Now, data from 2016 onward can only be requested from individual states or territories, which is a slow and difficult process. This puts a heavy burden on both researchers and local health departments.

Later in 2025, more CDC teams were fired. In October, two important groups lost their jobs — one that planned the National Health and Nutrition Examination Survey, which has tracked Americans' health and nutrition since 1999, and another that managed the National Death Index, a database that records causes of death. Both terminations were reversed within a few months, but the scare sent shock waves through the public health community. Researchers worried they might lose access to decades of important health records.

Trust is a huge part of how the CDC does its work. People and communities share personal health information with the agency, and local health departments help collect it. If people worry that their data might be shared without permission or used the wrong way, they may stop sharing it — or even stop seeking health care. Experts say that once trust is broken, it is very hard to rebuild.