Bird flu could be the next big health risk. Where's the vaccine?

NOW THAT THE WORLD HAS ADJUSTED TO LIVING WITH COVID-19, a new infectious disease threat is looming—this time from wild birds. Highly pathogenic avian influenza, or H5N1 bird flu, is spreading among dairy cattle that provide our milk and starting to cause serious disease in people. An elderly man with underlying health conditions became the first to develop severe disease in the U.S. and died in early January, and a 13-year-old girl with asthma in Canada became so sick with H5N1 in late 2024 that she had to be put on a ventilator.

- BY ALICE PARK

The U.S. Centers for Disease Control and Prevention (CDC) maintains that the risk to the general public is low, since H5N1 doesn't generally cause serious illness in people, but these recent cases are reason for public-health officials to prepare for wider outbreaks and a possible epidemic or pandemic. The key to that response will be an effective vaccine.

“The concern is that this virus could acquire the capacity to attach to human cells and spread widely. That would be opening the door to a new pandemic for sure,” says Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center and spokesperson for the Infectious Disease Society of America.

For that to happen, the virus would have to develop mutations that allow it to more easily infect human cells—a process that could be accelerated if someone were infected with both seasonal flu and H5N1, for instance, allowing the two viruses to exchange genetic information and recombine into a strain that spreads readily among people.