There has recently been substantial concern that highly pathogenic avian influenza virus A (H5N1) may have the potential to cause a pandemic.

The European Centre for Disease Prevention and Control describes H5N1 as:

highly infectious for a number of bird species, including most species of domestic poultry. Unlike most other avian influenza viruses, this virus has also infected mammals, including cats, pigs and tigers, and has shown to be able to transmit to humans. However, the virus remains poorly adapted to humans, and transmission from birds to humans is a rare event. Since the first detection of zoonotic transmission of HPAI A(H5N1), limited clusters of human cases have occurred but no sustained human-to-human transmission has been observed but showed.

While no sustained human-to-human transmission has been seen, there have recently been instances of sustained transmission between other mammals, including between minks. And there is very extensive ongoing transmission in avian populations — H5N1 has killed millions of wild and farmed birds and is behind the recent spike in egg prices in some countries.

According to the U.S. CDC, since December 2021 there have been less than 10 reported human cases of H5N1 globally.

A January 30, 2023 technical risk assessment by the UK Health Security Agency (UKHSA) assigns H5N1 a "level 3" risk level, which is when there is "Evidence of viral genomic changes that provide an advantage for mammalian infection.". They note "The apparent transmission between mink is of significant concern but there is no clear evidence that this has continued in mammalian species since the initial outbreak ... At present, there are no indicators of increasing risk to human health, however this is a low confidence assessment."

A "level 5" risk level by UKHSA would indicate "indicate "Any human-to-human transmission.".

Will there be any reported human-to-human transmission of H5N1 before 2024?

Based on 477 predictions by 113 forecasters