It was the kind of news that made scientists grab their phones and start texting colleagues.

H5N1, commonly called bird flu, had been detected in cows. Scientists had been closely watching avian flu for years, worried about the potential jump to livestock. But their money was on pigs next. This was late March 2024. Seema Lakdawala, PhD, remembers texting associates while on vacation with her family. The infection of cows “was very surprising,” said Lakdawala, associate professor of microbiology and immunology at the Emory University School of Medicine in Atlanta.

Then came another surprise: The virus was in the mammary glands. “It was thought to be respiratory,” Lakdawala said. The news got worse in April and May: Several human cases were identified — first in Texas, then in Michigan. In July, 10 more human cases were reported in Colorado. To Kamran Khan, MD, MPH, an infectious disease specialist, that suggested that the extent of H5N1 in livestock was “probably larger and more expansive than was understood at the time.”

The numbers jumped out at the experts: between 10 thousand and 10 million virus particles per milliliter of milk. “That’s when everyone went, ‘Whoa, let’s get on calls with the CDC and the USDA,’” Lakdawala said. The immediate response was “not very strong and is still not strong,” Lakdawala said in an interview in late April. Recent government cutbacks, she and others said, are thwarting prevention even more.

Now it’s more than a year later, and scientists are focused on two big questions: Could bird flu become a pandemic? How can we stop that from happening?

The CDC views the risk of bird flu to the public as low. Khan agrees — for now. “The concern is that this outbreak could quickly transform into a pandemic if the virus evolved so it is capable of efficiently spreading between humans,” said Khan, a professor of medicine at the University of Toronto and founder and CEO of BlueDot, a biothreat intelligence company.  “The reality is none of us knows whether this is next week, next year, or never,” he told 60 Minutes.  “I don’t think it’s never.”

According to the CDC, no known person-to-person spread of bird flu has occurred.  But 70 cases, including one death, have been confirmed in the U.S. Of those cases, exposure was mostly from dairy herds (41 cases), followed by poultry farms (24). Two others were from animal exposure such as backyard flocks, and three had an unknown source. When people get bird flu, the CDC says, it is most often after close and unprotected exposure to birds or other animals infected with the virus. Seventeen states had reported outbreaks in dairy cows and 1,049 dairy herds had been affected, according to the CDC.

The virus, as it’s understood now, “clearly is not able to multiply and be transmitted person-to-person efficiently,” said William Schaffner, MD, professor of infectious diseases at Vanderbilt University Medical Center in Nashville and spokesperson for the Infectious Diseases Society of America.