Why a teenager’s bird-flu infection is leaving scientists concerned

A teenager in Vancouver, Canada, is in critical condition after contracting an H5N1 avian influenza virus, raising concerns among researchers about the virus’s potential to adapt to humans.
Genome sequencing suggests that the virus has mutations that might enhance its ability to infect human airway cells, sparking fears about its evolution, according to a report in Nature.
Despite this development, experts have highlighted no immediate risk of a pandemic. “There is reason to be concerned, but not reason to totally freak out,” says Scott Hensley, an immunologist at the University of Pennsylvania. Importantly, no evidence has emerged of human-to-human transmission in this case.
The source of the infection remains unclear. The teen had no exposure to poultry farms or infected animals, and no cases have been identified among household pets, according to public health officer Bonnie Henry. She noted the possibility of never finding the infection’s source.
WHY IS THE VIRUS CONCERNING?
The virus shares similarities with strains circulating in poultry and waterfowl but carries three critical mutations: two that could help it infect human cells and one that might aid replication in human hosts. Researchers believe these mutations may have evolved within the infected teenager, as the virus initially caused an eye infection that progressed to severe lung infection.
Jesse Bloom, a virologist at the Fred Hutchinson Cancer Center, called the mutations a significant finding, suggesting that the virus is evolving in ways that merit attention.
IS BIRD FLU THE NEXT PANDEMIC?
Experts urge caution but not panic. No evidence suggests that this strain can easily spread among humans. “Being able to bind to human cells is a prerequisite for a pandemic but not sufficient,” Hensley explains.
Efforts are underway to prepare for potential risks. Vaccines developed for earlier H5N1 strains are being tested and might still offer protection.
While rare, H5N1 infections have historically been severe, particularly in young people, like the teenager currently battling the virus. Henry underscores the importance of vigilance: “This case reminds us that the virus can cause severe illness, even in healthy individuals.”