Almost half of US CDC databases due to be updated at least monthly were instead paused for significant time periods during 2025, the vast majority relating to vaccination-related topics, a new study reports.
The authors — led by Janet Freilich, a professor of law at Boston University School of Law — examined the metadata for all public CDC databases on October 28, 2025. They found that of 82 databases updated at least monthly, 38 (46%) had unexplained pauses. Most of the 38 covered data relating to vaccinations for influenza, COVID-19, or respiratory syncytial virus (RSV); one monitored RSV disease burden, another effectiveness in infants of nirsevimab, a monoclonal antibody treatment for RSV, and another on respiratory illnesses treated in the emergency department.
One non-infectious disease database — the Provisional Overdose Death Counts — was also paused, according to the study, published online January 26 in the Annals of Internal Medicine.
Freilich, who regularly studies government data, told Medscape Medical News that she undertook the study after noticing that some datasets had disappeared, and that many others were not being updated. “I wanted to get a sense of whether this was just an isolated incident with the datasets I was looking for or whether it was something more widespread and systematic,” she said.
Although the researchers looked at the data at a time when the federal government had been shut down for 27 days, that does not explain the pauses, said Freilich. The pauses primarily began in March and April 2025, soon after Robert F. Kennedy, Jr was confirmed as Department of Health and Human Services secretary, she and her colleagues report. Thirty-four of the 38 databases had no data entries during the previous 6 months, they found.
The lack of current information may have led to harm, the authors wrote.
“Many of these databases are specifically intended to be surveillance systems that give up-to-date information,” Freilich told Medscape. “Getting the data 6 months later doesn’t really help,” she said.
“We have relied on CDC for many decades to be our early warning system,” said Robert H. Hopkins, Jr, MD, medical director of the National Foundation for Infectious Diseases. In infectious disease and vaccines, “there are not a whole lot of other complementary systems that can give us that information,” Hopkins, who is also professor of internal medicine and pediatrics at the University of Arkansas for Medical Sciences, Fayetteville, told Medscape.
In an editorial accompanying the paper, Jeanne Marrazzo, MD, MPH, CEO of the Infectious Diseases Society of America, called it a “disturbing report.”
“The evidence is damning: The administration’s anti-vaccine stance has interrupted the reliable flow of the data we need to keep Americans safe from preventable infections,” wrote Marrazzo, who was fired in 2025 from her previous position as the director of the National Institute on Allergy and Infectious Disease (NIAID).
The study authors checked on the databases again on December 2 and found that only one had been updated.
Many Back Online, but Gaps Persist
It appears that some databases are now more current but still incomplete.
Hopkins noted there is updated data for how many adults and children received a flu vaccine but nothing for pregnant women. Instead, it says, “The summaries for the 2025-26 season will be populated as the data become available throughout the fall/Winter.”
“That’s unusual,” said Hopkins.
There are also gaps in current RSV vaccination data, including for pregnant women, and some adults over age 75, he said. That, too, is not usual, he said.
“When we don’t have data, it makes it really challenging to respond,” said Hopkins. “And if we don’t have data on immunization, it makes it hard to address communities that may have particular needs to improve their vaccination rates,” he said.
Without a national-level view of disease burden, “it makes it challenging in areas that are low to know, are they low because they just don’t have the disease, or they low because we don’t have the data?” he added.
Even if some of the databases are coming back online, it’s not clear how often they are being updated and how up-to-date the data is, said Hopkins.
Fiona Havers, MD, who helped oversee the CDC’s Respiratory Virus Hospitalization Surveillance Network and COVID tracking data before resigning in June 2025, told Medscape that the data in RESP-NET is “still reliable.”
Many of those databases had been paused but are back online.
“But I am concerned that if the CDC budget continues to be slashed and staff continue to be fired or leave, that CDC won’t be able to continue to track those important public health measures with the same level of accuracy,” said Havers, now an adjunct associate professor at Emory School of Medicine in Atlanta.
Reasons for Pauses Unclear
The authors said they couldn’t determine the reasons for why so many databases had been paused. Layoffs at the CDC, budget constraints, and “changing governmental policy directives,” may all have played a role, they wrote.
Hopkins said that “the implication of the article is that some of this may be intentional,” adding, “the fact that it seems to be skewed toward databases of things related to vaccination, and vaccine preventable diseases, at least gives that impression to me,” he said.
Marrazzo, in the editorial, said it did not matter whether the pauses were due to CDC layoffs or if they were intentional. “Either causative pathway demonstrates a profound disregard for human life, scientific progress, and the dedication of the public health workforce that has provided a bulwark against the advance of emerging, and reemerging, infectious disease,” she wrote.
Freilich, Havers, and Hopkins had no disclosures. Marrazzo is suing the Trump administration alleging that she was illegally fired from NIAID after filing a whistleblower complaint.
Alicia Ault is a Saint Petersburg, Florida-based freelance journalist whose work has appeared in many health and science publications, including Smithsonian.com. You can find her on X @aliciaault and on Bluesky @aliciaault.bsky.social.
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