Austin, Texas – The World Health Organization has issued warnings about the concerning spread of H5N1 bird flu, highlighting its remarkably high mortality rate in humans.

Since the onset of an outbreak in 2020, tens of millions of poultry have succumbed to the virus. Recent reports indicate its transmission to various mammal species, including domestic cattle in the US, intensifying the risk of cross-species infection to humans, as stated by the WHO.

Chief scientist Jeremy Farrar expressed his unease during a press briefing in Geneva, emphasizing the unexpected infections in cows and goats last month. This revelation puzzled experts as these animals were not believed to be susceptible to this strain of influenza. A recent case in Texas showed a person recovering from bird flu after exposure to infected dairy cattle, with 16 herds across six states becoming infected, likely through contact with wild birds.

Describing the A(H5N1) variant as a “global zoonotic animal pandemic,” Farrar stressed the looming threat of the virus evolving the ability to infect humans and potentially facilitate human-to-human transmission. Despite no confirmed instances of human-to-human spread, the mortality rate for those infected with H5N1 through animal contact over the past two decades remains alarmingly high due to the lack of natural immunity in humans.

With 889 reported cases and 463 fatalities from H5N1 worldwide since 2003, the WHO reports a staggeringly high case fatality rate of 52%. The recent case of human infection in the US following contact with an infected mammal underscores the escalated risk, with Farrar cautioning about the virus seeking novel hosts as it crosses into mammalian populations.

Farrar emphasized the urgency of enhanced monitoring to track potential human infections, underscoring the necessity for swift responses in the event of human-to-human transmission. Efforts towards developing vaccines and therapeutics for H5N1 are underway, with a critical emphasis on ensuring global health authorities are equipped to diagnose the virus promptly and effectively. The need for equitable access to vaccines, therapeutics, and diagnostics is paramount to preemptively tackle any potential outbreak of H5N1.