Urgent CDC Data and Analyses on Influenza and Bird Flu Go Missing as Outbreaks Escalate

Sonya Stokes, an emergency room physician in the San Francisco Bay Area, braces herself for a daily deluge of patients sick with coughs, soreness, fevers, vomiting, and other flu-like symptoms.

She’s desperate for information, but the Centers for Disease Control and Prevention, a critical source of urgent analyses of the flu and other public health threats, has gone quiet in the weeks since President Donald Trump took office.

“Without more information, we are blind,” she said.

Flu has been brutal this season. The CDC estimates at least 24 million illnesses, 310,000 hospitalizations, and 13,000 deaths from the flu since the start of October. At the same time, the bird flu outbreak continues to infect cattle and farmworkers. But CDC analyses that would inform people about these situations are delayed, and the CDC has cut off communication with doctors, researchers, and the World Health Organization, say doctors and public health experts.

“CDC right now is not reporting influenza data through the WHO global platforms, FluNet [and] FluID, that they’ve been providing information [on] for many, many years,” Maria Van Kerkhove, interim director of epidemic and pandemic preparedness at the WHO, said at a Feb. 12 press briefing.

“We are communicating with them,” she added, “but we haven’t heard anything back.”

On his first day in office, President Donald Trump announced the U.S. would withdraw from the WHO.

A critical analysis of the seasonal flu selected for distribution through the CDC’s Health Alert Network has stalled, according to people close to the CDC. They asked not to be identified because of fears of retaliation. The network, abbreviated as HAN, is the CDC’s main method of sharing urgent public health information with health officials, doctors, and, sometimes, the public.

A chart from that analysis, reviewed by KFF Health News, suggests that flu may be at a record high. About 7.7% of patients who visited clinics and hospitals without being admitted had flu-like symptoms in early February, a ratio higher than in four other flu seasons depicted in the graph. That includes 2003-04, when an atypical strain of flu fueled a particularly treacherous season that killed at least 153 children.

Without a complete analysis, however, it’s unclear whether this tidal wave of sickness foreshadows a spike in hospitalizations and deaths that hospitals, pharmacies, and schools must prepare for. Specifically, other data could relay how many of the flu-like illnesses are caused by flu viruses — or which flu strain is infecting people. A deeper report might also reveal whether the flu is more severe or contagious than usual.

“I need to know if we are dealing with a more virulent strain or a coinfection with another virus that is making my patients sicker, and what to look for so that I know if my patients are in danger,” Stokes said. “Delays in data create dangerous situations on the front line.”

Although the CDC’s flu dashboard shows a surge of influenza, it doesn’t include all data needed to interpret the situation. Nor does it offer the tailored advice found in HAN alerts that tells health care workers how to protect patients and the public. In 2023, for example, a report urged clinics to test patients with respiratory symptoms rather than assume cases are the flu, since other viruses were causing similar issues that year.

“This is incredibly disturbing,” said Rachel Hardeman, a member of the Advisory Committee to the Director of the CDC. On Feb. 10, Hardeman and other committee members wrote to acting CDC Director Susan Monarez asking the agency to explain missing data, delayed studies, and potentially severe staff cuts. “The CDC is vital to our nation’s security,” the letter said.

Several studies have also been delayed or remain missing from the CDC’s preeminent scientific publication, the Morbidity and Mortality Weekly Report. Anne Schuchat, a former principal deputy director at the CDC, said she would be concerned if there was political oversight of scientific material: “Suppressing information is potentially confusing, possibly dangerous, and it can backfire.”

CDC spokesperson Melissa Dibble declined to comment on delayed or missing analyses. “It is not unexpected to see flu activity elevated and increasing at this time of the year,” she said.

A draft of one unpublished study, reviewed by KFF Health News, that has been withheld from the MMWR for three weeks describes how a milk hauler and a dairy worker in Michigan may have spread bird flu to their pet cats. The indoor cats became severely sick and died. Although the workers weren’t tested, the study says that one of them had irritated eyes before the cat fell ill — a common bird flu symptom. That person told researchers that the pet “would roll in their work clothes.”

After one cat became sick, the investigation reports, an adolescent in the household developed a cough. But the report says this young person tested negative for the flu, and positive for a cold-causing virus.

Corresponding CDC documents summarizing the cat study and another as-yet unpublished bird flu analysis said the reports were scheduled to be published Jan. 23. These were reviewed by KFF Health News. The briefing on cats advises dairy farmworkers to “remove clothing and footwear, and rinse off any animal biproduct residue before entering the household to protect others in the household, including potentially indoor-only cats.”

The second summary refers to “the most comprehensive” analysis of bird flu virus detected in wastewater in the United States.

Jennifer Nuzzo, director of the Pandemic Center at Brown University, said delays of bird flu reports are upsetting because they’re needed to inform the public about a worsening situation with many unknown elements. Citing “insufficient data” and “high uncertainty,” the United Kingdom raised its assessment of the risk posed by the U.S. outbreak on dairies.

“Missing and delayed data causes uncertainty,” Nuzzo said. “It also potentially makes us react in ways that are counterproductive.”

Another bird flu study slated for January publication showed up in the MMWR on Feb. 13, three weeks after it was expected. It revealed that three cattle veterinarians had been unknowingly infected last year, based on the discovery of antibodies against the bird flu virus in their blood. One of the veterinarians worked in Georgia and South Carolina, states that haven’t reported outbreaks on dairy farms.

The study provides further evidence that the United States is not adequately detecting cases in cows and people. Nuzzo said it also highlights how data can supply reassuring news. Only three of 150 cattle veterinarians had signs of prior infections, suggesting that the virus doesn’t easily spread from the animals into people. More than 40 dairy workers have been infected, but they generally have had more sustained contact with sick cattle and their virus-laden milk than veterinarians.

Instead, recently released reports have been about wildfires in California and Hawaii.

“Interesting but not urgent,” Nuzzo said, considering the acute fire emergencies have ended. The bird flu outbreak, she said, is an ongoing “urgent health threat for which we need up-to-the-minute information to know how to protect people.”

“The American public is at greater risk when we don’t have information on a timely basis,” Schuchat said.

This week, a federal judge ordered the CDC and other health agencies to “restore” datasets and websites that the organization Doctors for America had identified in a lawsuit as having been altered. Further, the judge ordered the agencies to “identify any other resources that DFA members rely on to provide medical care” and restore them by Feb. 14.

In their letter, CDC advisory committee members requested an investigation into missing data and delayed reports. Hardeman, an adviser who is a health policy expert at the University of Minnesota, said the group didn’t know why data and scientific findings were being withheld or removed. Still, she added, “I hold accountable the acting director of the CDC, the head of HHS, and the White House.”

Hardeman said the Trump administration has the power to disband the advisory committee. She said the group expects that to happen but proceeded with its demands regardless.

“We want to safeguard the rigor of the work at the CDC because we care deeply about public health,” she said. “We aren’t here to be silent.”

KFF Health News is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF—an independent source of health policy research, polling, and journalism. Learn more about KFF.

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This article first appeared on KFF Health News and is republished here under a Creative Commons license.