H5N1 bird flu in U.S. cattle: A wake-up call to action

The recent detection of H5N1 bird flu in U.S. cattle, coupled with reports of a dairy worker contracting the virus, demands a departure from the usual reassurances offered by federal health officials. While they emphasize there’s no cause for alarm and assert diligent monitoring, it’s imperative we break from this familiar script.

H5N1, a strain of the flu virus known to infect bird species globally and several mammalian species in the U.S. since 2022, has now appeared to have breached a new barrier of inter-mammalian transmission, as exemplified by the expanding outbreak in dairy cows in several jurisdictions linked to an initial outbreak in Texas. Over time, continued transmission among cattle is likely to yield mutations that will further increase the efficiency of mammal-to-mammal transmission.

As the Centers for Disease Control continues to investigate, this evolutionary leap, if confirmed, underscores the adaptability of the H5N1 virus and raises concerns about the next step required for a pandemic: its potential to further evolve for efficient human transmission. Because humans have no natural immunity to H5N1, the virus can be particularly lethal to them. Despite assertions of an overall low risk of H5N1 infection to the general population, the reality is that the understanding of this risk is limited, and it’s evolving alongside the virus. The situation could change very quickly, so it is important to be prepared.

Comparisons to seasonal flu management underestimate the unique challenges posed by H5N1. Unlike its seasonal counterparts, vaccines produced and stockpiled to tackle bird flu were not designed to match this particular strain and are available in such limited quantities that they could not make a dent in averting or mitigating a pandemic, even if deployed in the early stages to dairy workers. The FDA-approved H5N1 vaccines — licensed in 2013, 2017, and 2020 — do not elicit a protective immune response after just one dose. Even after two doses, it is unknown whether the elicited immune response is sufficient to protect against infection or severe disease, as these vaccines were licensed based on their ability to generate an immune response thought to be helpful in preventing the flu.

Early studies done by mRNA vaccine companies on seasonal flu are promising, which could be good news here since mRNA vaccines can be made more quickly than vaccines using eggs or cells. Congressional funding is needed to catalyze rapid vaccine development and production.

While FDA-approved antiviral drugs like Tamiflu and Xofluza could be an important line of defense against H5N1, logistical barriers impede their timely administration, as they work best when given as early as possible within 48 hours of the onset of symptoms. Most Americans would find it challenging to get a prescription filled for these medicines within the optimal time frame. Streamlining access to stockpiled antiviral drugs through improved test-to-treat measures like behind-the-counter distribution or dedicated telemedicine consultations could vastly improve their effectiveness as a frontline defense. Making plans to do that need to start now.

For vulnerable people — older adults and anyone who is immunocompromised — clinicians have become accustomed to relying on monoclonal antibodies. Sadly, their performance for flu has been disappointing in many clinical trials and can’t be counted on.

The need for robust diagnostic capabilities cannot be overstated. H5N1 will not be detected by the typical rapid flu antigen tests that are administered in emergency rooms and many doctors’ offices. New tests will have to be made from scratch. The dismantling of diagnostic infrastructure post-Covid-19 and supply chain disruptions, however, pose significant challenges to the availability of such tests. Rapid investment in diagnostic testing, coupled with efforts to secure essential materials, is imperative to ensure timely detection and antiviral treatment.

President Biden’s emphasis on infrastructure presents a unique opportunity to fortify America’s defenses against infectious diseases. A national initiative to enhance indoor air quality in schools and communal spaces could mitigate transmission risks should this virus learn how to efficiently be transmitted between humans, and would pay dividends every respiratory virus season and for years to come.

In the face of uncertainty, complacency is not an option. The U.S. must act decisively, acknowledging the potential gravity of the H5N1 situation while leveraging every available resource to safeguard public health. The stakes are too high to repeat past mistakes.

Luciana Borio is an infectious disease physician, a senior fellow for global health at the Council on Foreign Relations, a venture partner at ARCH Venture Partners, and former director for medical and biodefense preparedness policy at the National Security Council. Phil Krause is a virologist, infectious disease physician, and former deputy director of the Office of Vaccines Research and Review at the FDA. The authors have no links to any companies producing or evaluating any of the vaccines or therapies mentioned in this article, and declare no conflicts of interest.