French infectious disease specialists are warning that the bird flu virus, currently spreading among wild birds, poultry, and some mammals, could cause a pandemic more severe than COVID-19 if it mutates to spread efficiently between humans. Marie-Anne Rameix-Welti, medical director at the Institut Pasteur’s respiratory infections centre, said the virus’s adaptation to mammals is a major concern. “If it becomes capable of human-to-human transmission, that virus would be a pandemic virus,” she told Reuters.
Highly pathogenic avian influenza has already led to the culling of hundreds of millions of birds worldwide, causing food shortages and driving up prices. Although human infections remain rare, ongoing cases in people highlight the potential risk.
Lack of Immunity Makes Humans Vulnerable
A critical concern is that humans have no natural immunity to the H5 bird flu strain. Unlike common seasonal flu strains like H1 and H3, the body has no pre-existing antibodies to H5—similar to the early stages of COVID-19. Rameix-Welti explained that, unlike COVID-19, influenza viruses can severely affect healthy individuals, including children.
Human infections with H5 viruses have occurred over the years, often in people in close contact with infected animals. In the U.S. this month, the first ever human case of H5N5 was reported in Washington state; the infected man, who had underlying conditions, later died. According to the World Health Organization, nearly 1,000 human outbreaks of bird flu have been recorded between 2003 and 2025, with a fatality rate of 48%, mainly in Egypt, Indonesia, and Vietnam.
Preparedness Could Reduce Impact
Despite the warnings, experts emphasize that the risk of a human pandemic remains low. Gregorio Torres of the World Organisation for Animal Health said people can continue their daily activities safely, as the probability of widespread transmission is still small.
Rameix-Welti highlighted that the world is better prepared than it was before COVID-19. Vaccine candidates are already available, production can be scaled up quickly, and antiviral stockpiles exist. These measures, she said, could help contain the virus if it ever mutates to spread between humans.
While vigilance is necessary, current health systems have tools to respond, providing some reassurance amid concerns about the bird flu’s pandemic potential.
