And needless to say, it ain’t over.

“It” being highly pathogenic avian influenza.

The disease among wild birds and poultry flocks has backed off of its virulent spread of a year ago, and the poultry supply chain could be forgiven for letting out a sigh of relief. But let’s not get too comfortable with the past tense just yet.

As pointed out in this article in the Bulletin of the Atomic Scientists, while the H5N1 strain killed more than half of the people who became infected with it across the globe over the last 20 years, the virus has been rarely transmissible among humans. “Since around 2015, human H5N1 cases and fatalities have almost disappeared,” the article notes.

Nature has taken its course, apparently, with the virus mutating into less dangerous strains as it spread among fowl. Except, that’s not the whole story.

Viruses mutate in multiple directions at once, including mutations that render it more easily transmitted between and among species. The Bulletin article calls out a 2012 study that “found that of five changes to H5N1 that were thought to make the virus transmissible among ferrets, two were already common in nature. Just three more changes and H5N1, a virus that essentially only infects people with close contact to birds, could become a pandemic threat.”

Nobody, including me, throws the word “pandemic” around lightly these days, if they ever did. So let’s take a look at the situation as it stands now:

As The Lancet has noted, beginning 2021, HPAI has remained present year-round in wild birds in Europe, spread across North America, and still is spreading southward in South America.
In addition to the destruction of more than 100 million birds globally, we’ve seen repeated H5N1 outbreaks among mammals, such as seals and mink — about 30 different mammal species altogether.
How the virus is spreading among mammals hasn’t been proven, but spreading through the air, like COVID-19 does, cannot be ruled out.

According to the World Health Organization, the number of human deaths due to H5N1 have been 0 or 1 each year since 2018, all in Asian countries. In 2022 and 2023, the number of cases have been climbing.

As we have learned, the way viruses jump from animals to humans, and then from human to human, can be devastating. The poultry supply chain needs to figure out how to get ahead of even the specter of a bird flu pandemic.

Actually doing that will take some global-level cooperation. Inoculating the birds and other animals has proven effective in the past, in China, where a poultry vaccination mandate is believed to have stopped a localized epidemic of H7N9 in its tracks in 2018. In the U.S., however, getting producers to administer vaccines to their flocks has to overcome the hurdle of cost, a speed bump that has stymied other efforts to address threats — typically pathogens — at the front end of the supply chain.

Furthermore, viruses mutate rapidly, reducing a vaccine effectiveness. Birds could still shed the virus. Introducing a vaccine could change international trade relationships, as some countries won’t import vaccinated birds.

The path to preventing a deadly resurgence of HPAI, then, is not straight and not smooth. The complications mean that the USDA and possibly FDA need to apply some pressure, and some funding, toward an all-out effort to find solutions. Beyond the government's efforts, though, given H5N1’s virulence in humans, the poultry supply chain should consider corralling the virus among its top long-term priorities, while it's still a threat mostly to the birds.

It ain’t over ‘til it’s over

Join for free* to continue reading.