As a bird flu outbreak continues to escalate across the United States, the Trump administration has halted the release of critical public health studies, delaying research that could shed light on the virus’s transmission among animals and humans.

The blocked studies, slated for publication in the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report (MMWR)—a respected source of public health information since 1952—are now caught in limbo. One report investigates whether veterinarians working with cattle have inadvertently contracted the virus, while another examines potential transmission of the virus from people to pet cats.

A memo issued by the Department of Health and Human Services (HHS) mandates an “immediate pause” on these communications, requiring approval from a presidential appointee before any publication can proceed. Critics argue that this move undermines the transparency and objectivity of scientific research.

“This idea that science cannot continue until there’s a political lens over it is unprecedented,” said Dr. Anne Schuchat, former principal deputy director at the CDC. “I hope it’s going to be very short-lived, but if it’s not short-lived, it’s censorship.”

Public health experts warn that any delay in disseminating research on the bird flu could heighten the risk for veterinarians, farmworkers, and the general public. One of the pending studies, which was due to be published last week in the MMWR, examined cases in Michigan where dairy workers may have transmitted bird flu to their pet cats. Dr. Jennifer Morse, medical director at the Mid-Michigan District Health Department and a contributing scientist on the study, confirmed that colleagues had noted delays beyond their control.

The decision to pause these reports has drawn comparisons to past incidents during President Donald Trump’s first term when government officials were accused of interfering with COVID-19 research. “What’s happening now is quite different than what we experienced in COVID, because there wasn’t a stop in the MMWR and other scientific manuscripts,” Schuchat noted.

CDC insiders expect the pause to last until at least February 6, although it remains uncertain whether publications will resume on schedule. The bird flu outbreak has so far infected at least 67 people in the U.S., including one fatality in Louisiana earlier this year, and has affected more than 148 million birds, intensifying concerns about potential human transmission.

“Maintaining open lines of communication and continuing research with our federal partners is critical as we fight this outbreak,” said Dr. Fred Gingrich, executive director of the American Association of Bovine Practitioners.

As the outbreak continues, public health officials and researchers stress the importance of unfettered scientific inquiry to develop timely and effective interventions. Critics of the recent publication halt hope that political influence will not compromise the integrity of future CDC reports.