Roberta Villa, MD

DISCLOSURES | December 09, 2024

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It’s been a while since I’ve discussed the H5N1 avian influenza clade 2.3.4.4b and its rapid spread in North America. I hope the facts prove me wrong, but many experts have been warning for some time that ideal conditions are forming for this virus, which for now only causes zoonoses, to pose a pandemic threat.

Let me recap for anyone who may have missed some of the developments, either because they work in other medical fields or think that the experience of the COVID-19 pandemic was a worst-case scenario that is unlikely to be repeated in the short term.

The Virus Has Flown to Hawaii

According to data from the Centers for Disease Control and Prevention in Atlanta, the infection has now affected more than 500 cattle herds in 15 states. There are about 30 outbreaks reported in poultry, equally distributed between backyard and farm-raised birds, primarily located in California. Here alone, over 3 million birds have been affected. 

Wild birds are believed to have transported the highly pathogenic virus via migration routes across the Pacific, introducing it to Hawaii for the first time. Just days after wastewater analysis detected the presence of H5N1 on the island of Oahu, home to the capital Honolulu, the first outbreak was promptly reported, killing at least a dozen ducks and geese in a backyard coop. Some of these birds had been taken in early November to the Mililani Pet Fair, a sort of domestic animal festival. Local authorities recommended that anyone who attended the fair, touched a duck or goose at the event, and developed symptoms including fever, cough, sore throat, and conjunctivitis, should isolate and seek medical advice.

Meanwhile, more than 50 farmers, animal handlers, or workers involved in the slaughter of cattle or poultry across seven states have been confirmed infected, presumably contracted at their workplace. The latest case, diagnosed recently in Oregon, presented with severe conjunctivitis and mild respiratory symptoms. More than half of these patients have been identified in recent weeks in California, where active surveillance measures have been implemented. However, there is strong suspicion that the actual number of people infected with mild symptoms in the rest of the country is much, much higher.

The Red Alert Lights Up in Canada

The level of concern was raised further with news of the first severe — indeed very severe — case of H5N1 avian influenza originating from the western edge of Canada. A teenager (gender not disclosed), previously healthy and without risk factors, was hospitalized with severe respiratory failure in the intensive care unit at British Columbia Children’s Hospital in Vancouver. The source of the infection is unknown, similar to only one other case in Missouri involving an adult already hospitalized for other reasons, which was identified by chance through influenza surveillance programs. We also know that the Canadian adolescent does not live on a farm and had no known contact with potentially infected animals. The only suspicions focus on the family dog, euthanized owing to unspecified health problems in the early days of the epidemiologic investigation. Although the dog tested negative for avian influenza, a necropsy will be conducted to rule out its involvement in the transmission chain.

An initial characterization of the virus has linked it to genotype D1.1, which is circulating among wild birds and poultry farms in Canada’s westernmost province, rather than the strain typical of dairy cows in the United States. The publication of the complete viral sequence over the past weekend has, for the first time, highlighted mutations that could enhance the virus’s ability to infect human cells.

How do we know this? From the highly contested “gain-of-function” studies, which artificially modify viruses to understand which genomic points require the most surveillance — those mutations that can make the infectious agent more virulent or more transmissible between people.

Under Special Surveillance for 20 Years

The influenza A (H5N1) avian virus is not new or previously unknown, like SARS-CoV-2, and this could (in theory) give us a slight advantage. We have known about it for decades, and it began infecting humans about 20 years ago, causing pneumonia with respiratory failure. It proved lethal in about half of the cases, but only in people who had close contact with infected poultry, primarily in Southeast Asia.

Hundreds of other human cases occurred worldwide, but always in low-income countries with poor hygiene conditions and where families lived in close contact with animals. This contributed to a false sense of security in Europe and North America, where the threat has been consistently underestimated. Despite an estimated fatality rate of around 50%, the media often labeled scientists’ warnings and health authorities’ efforts to remain prepared as false alarms, tainted by suspicions of catering to the interests of pharmaceutical companies.

Some people may recall the scandal involving Tamiflu, the Roche antiviral oseltamivir, that governments stockpiled when there were fears that the avian virus might acquire the ability to spread among humans. It was dubbed “a false antidote for a false pandemic,” referring to the potential avian pandemic and the 2009 H1N1 influenza pandemic, improperly called “swine flu,” and which turned out to be less severe than expected. There was talk of €2.64 billion being “wasted” to “please” the manufacturer. Although the Cochrane Collaboration made legitimate demands for rigor and transparency in conducting and publishing clinical trials, much of the public, and the journalists who wrote the stories, cared little about these technical aspects. The prevailing message was that stockpiling drugs (or vaccines) for a disease we don’t even know will occur is a waste of taxpayers’ money rather than a prudent preventive measure.

More Vulnerable Than Ever

If we were to ascribe strategic thinking to the virus, which it is not capable of, we might argue that it chose the ideal moment to conquer the world. It began circulating in the new clade in 2020, when experts and authorities were focused on the coronavirus. It spread from birds to marine mammals and finally to cattle, exploiting the public’s post-pandemic fatigue, as people no longer wanted to hear about infectious diseases and containment measures. It ultimately rode the wave of political polarization that irrationally equates prevention with supposed cowardice on the left, and recklessness with courageous freedom on the right.

The coincidence between the future appointments announced by the incoming Trump administration and the virus’s accelerated spread deserves attention from decision-makers and health professionals worldwide. The COVID-19 pandemic experience should have taught us that ignoring a threat doesn’t make it go away, if not in our health, then at least in our wallet. The economic repercussions of a virus circulating among animals crucial to our food chain and national economies should concern everyone, well before the threat crosses the ocean, because only then can we defend ourselves.

The proposed Secretary of Health and Human Services, Robert F. Kennedy, is a proponent of the supposed benefits of raw milk, which could serve as a potent vector for the virus. He is ideologically opposed to vaccinations. It’s hard to imagine he would utilize the H5N1 vaccine stockpiles held by the US government for a campaign starting at least with farmers, as was done prophylactically in Finland with products jointly procured by 15 European countries — a group the Italian government decided not to join.

If Kennedy indeed becomes responsible for US public health, it’s reasonable to fear that, in the name of freedom, he will try to delay as much as possible — even if necessary — the obligation to undergo testing and wear masks, not to mention more restrictive infection containment measures. It’s also unlikely he would support and promote the development of new mRNA products already under study, which would become indispensable if the disease begins to spread more easily among people, as well as animals. In such a case, traditional influenza vaccine cultivation methods using chicken eggs would prove too slow and quantitatively insufficient, especially if the virus continues to circulate among poultry.

In short, let’s keep our fingers crossed, but recognize that crossing our fingers might not be enough.

This story was translated from Univadis Italy using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. 

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