THE UNITED STATES NEEDS TO STEP UP ITS RESPONSE TO BIRD FLU

By Michaela Simoneau, Sophia Hirshfield, and Maclane Speer

As 2024 closes, the United States continues to fall short in its management of the threat posed by bird flu, or H5N1. The virus causes regular outbreaks in wild birds and livestock across the world that generate serious agricultural and economic disruptions. But H5N1 can also spill over from birds to infect other animals, including humans.

On March 24, 2024, the virus was detected among dairy cows for the first time in the United States. Since then, the U.S. Centers for Disease Control and Prevention (CDC) has reported 61 human cases of H5N1 across eight states. For now, the risk of H5N1 to the general public appears to remain low, as the virus does not spread easily between people.

Recently, human cases of unknown origin in Missouri, California, and Vancouver have raised alarm bells that the virus might develop the capability for human-to-human transmission, which in turn might unleash a larger epidemic. The virus’s potential to rapidly mutate and cause high mortality rates among people—up to 50 percent—has had public health experts on high alert.

No one can reliably predict whether or when the current outbreak will evolve into a more serious threat to human health. Since 1997, there have been several scares from H5N1 when the virus did not develop the ability to pass between people, and this pattern is not well understood. But if H5N1 did cross that threshold, it is unlikely U.S. officials would be able to detect it in time to mobilize an effective response.

Since the turn of the century, every presidential administration has highlighted gaps in U.S. public health capabilities, and every Congress has left them underfunded. The H5N1 outbreak has revealed the resulting and dangerous shortcomings in U.S. pandemic preparedness: lagging data, incomplete surveillance, sluggish coordination, considerable mistrust, and insufficient planning and stockpiling of vaccines and therapies. That poor performance cuts across political parties, the federal interagency, and state leadership. Multiple players have sought to downplay the threat: the dairy industry fears further economic setbacks, state leaders are wary of federal intervention, and the Biden administration did not want to aggravate relations during the 2024 election cycle.

It is not too late to change course. Strong interagency, interstate, and global coordination; better protections for farm workers; accelerated planning and investment in surveillance; and the development and promotion of better vaccines and therapies remain the essential elements to prevent the sustained spread of H5N1.

THE SCOPE OF THE THREAT

It is important not to be alarmist. An additional mutation or mutations would need to occur for the current strain in dairy cows—or that circulating in wild birds—to become well adapted to human-to-human transmission.

Human cases have been mostly mild so far, with patients presenting with conjunctivitis and sometimes respiratory symptoms. However, this reality could change quickly, as evidenced by a serious case in a critically ill teenager in Vancouver, and a hospitalized patient with a severe case in Louisiana.

H5N1 is extremely contagious and lethal in chickens, and poultry outbreaks cause significant agricultural and economic hardship. Farmers have to depopulate entire flocks exposed to the virus—those losses have contributed to a 30 percent rise in egg prices in the past year. The hardest hit states, such as California, which just declared a state of emergency, will take months to recover.

Encouragingly, to date, most infected cows have not gotten severely ill, and the safety of the food supply chain has remained intact; humans are not at risk of getting the virus from pasteurized milk or properly prepared meat.

Scientists, veterinarians, and public health officials are concerned because the recent H5N1 outbreak in cows is not the only new development—it is one among a pattern of worrisome firsts for the virus.

H5N1 TRANSMISSION

As the virus has spread through wild birds to poultry flocks and dairy herds across the United States, H5N1 has also been detected in a growing number of wild species of mammals. It is unclear exactly how and to what extent the virus is spilling over among birds, cows, pigs, and other species.

CHALLENGES IN COORDINATING AN EFFECTIVE RESPONSE

The Covid-19 pandemic catalyzed key investments in outbreak response, including for disease surveillance, the development of vaccines and therapies, personal protective equipment (PPE), and greater attention to improving trust and coordination between communities, local officials, and national public health decisionmakers.

That response mainly involved the human health sector, whereas animals are the source of 75 percent of emerging infectious disease threats. In the H5N1 outbreak and increasingly in future outbreaks, public health experts should instead prepare to follow a  “One Health” approach—an integrated response among human, animal, and environmental health experts.

Executing such a coordinated response brings several new challenges.

ON THE GROUND

Since the beginning of the outbreak, there have been serious coordination challenges, with deep interagency tensions among the White House, CDC, Administration for Strategic Preparedness and Response (ASPR), and U.S. Department of Agriculture (USDA). Guidance from national-level officials has not always been clear for under-resourced veterinarians and public health officials at the local level.

The agricultural industry, USDA, and state-level agencies have mixed mandates to protect animal health while simultaneously ensuring the stability and productivity of the food market. Importantly, they are distinct from the CDC and state public health agencies with a mandate to protect human health.

Officials originally hesitated to restrict the movement of herds for fear of disrupting production or alienating and losing access to farmers. While the USDA began to require H5N1 testing for lactating cattle moving across state lines in May 2024, restrictions on intra-state movement vary.

Reliable testing of both animals and at-risk humans is necessary to track exposures and viral evolution. But since farmers fear that reporting infections could risk economic losses, many have refused or delayed testing.

Farm workers with mild symptoms are unlikely to seek testing and treatment if they lack insurance or sick leave. In addition, farm workers may come from at-risk populations, including undocumented immigrants, and face language barriers or mistrust authorities.

Dairy farms do not have sufficient or consistent biosecurity measures in place to control transmission of the virus. Even with additional support from the USDA and CDC, adding PPE or cleaning protocols can be expensive and inconvenient.

Altogether, these factors have caused cases to go woefully underreported. So long as the virus is circulating—especially undetected—it has the time and potential to evolve into a more transmissible and deadly variant.

TRACKING THE VIRUS

Reliable, real-time surveillance is essential for public health officials to institute targeted, protective measures to prevent the further spread of H5N1.

However, that real-time picture does not currently exist.

Despite a strong Animal Health Laboratory Network, testing and sequencing samples from infected animals is inconsistent, and may be reported with little detail and lengthy delay.

The USDA took an important step with its new National Milk Testing Strategy, requiring dairy farms, transporters, and processing facilities to submit raw milk samples for testing and requiring cattle owners with H5-positve animals to share information for testing and surveillance. Building on lessons from milk testing in Colorado, these measures should help identify areas where H5N1 is spreading among cattle asymptomatically, and where further investigation or quarantine are needed.

On the human health side, Covid-era investments in CDC programs have enabled the testing of thousands of possible H5N1 specimens over the past 10 months. Yet those programs are limited, rely on cooperation from individual states, and are in jeopardy as supplemental pandemic funding tapers off.

The CDC has issued several commercial contracts to increase diagnostic capacity in case demand spikes, and is piloting programs with pharmacies to provide free testing.

Decisionmakers need efficient surveillance to assess the risk of H5N1 to human health and to understand if the outbreak has moved into a new phase. Without those signals, there cannot be sufficient lead time to accelerate the production of critical medical countermeasures.

DEPLOYING VACCINES AND THERAPIES

Many regular tools to fight seasonal influenza remain effective against H5N1—to a point.

The CDC has broadened recommendations for Tamiflu (oseltamivir), a post-exposure prophylaxis for farm workers, which appears to remain an effective therapy against current strains of H5N1. However, it requires a prescription, and it works best when taken within 48 hours of symptom onset. Some experts worry that overreliance on Tamiflu is preventing the U.S. government from investing in the development of new, alternative therapies that could be more effective against severe cases in the event of a pandemic.

While PPE use is recommended by the CDC and increased in some high-risk areas after H5N1 was found in cows, not all workers are willing to adhere to guidance. Environmental conditions on farms and in milking parlors can make it uncomfortable to wear certain types of PPE, especially masks and respirators.

The CDC has allocated over 100,000 doses of the seasonal influenza vaccine to 12 states with bovine cases. These vaccines do not protect workers against H5N1, but they could help reduce severe seasonal flu cases, minimizing the risk of coinfection and further reassortment with seasonal and avian influenza.

Additionally, the United States holds a reserve of human H5N1 vaccines in the Strategic National Stockpile. The federal government has pledged to increase the stockpile to 10 million doses by the spring of 2025 and has made investments to ensure that those vaccines would be ready to distribute if need be.

Given that individuals need two doses of the vaccine to develop effective immunity, the stockpile would only be sufficient to vaccinate five million people. And stockpiled vaccines may become less effective in the face of rapid mutations.  

TIME TO GET SERIOUS ABOUT H5N1

The response to the H5N1 outbreak among dairy cows has revealed persistent weaknesses in U.S. public health preparedness, coordination failures among the animal and human health sectors, and a disconnect among agencies and between federal and state, tribal, local, and territorial jurisdictions. Recent policy and legislative advances have proven important but insufficient.

The U.S. government needs to significantly upgrade its engagement of governors, state and local leaders, and U.S. industry and provide additional resources to prepare for, detect, and respond to One Health threats like H5N1.

Although the risk of widespread human-to-human transmission of H5N1 in the United States currently appears to be low, the landscape could change rapidly. Four key actions are needed.

DO NOT WAIT
FOR PANIC

It is not time to panic about bird flu. Nor is it the time for complacency and hoping the virus will burn itself out.

So long as H5N1 spreads unchecked, there is a risk that the virus will evolve into a major human pandemic. Preventing the health and economic disruptions of an emergency of that scale is critical for the stability and national security of the United States.

White House leadership will be essential to drive progress and overcome the divisions that have blocked an effective response.

There is an opportunity to make investments in health security infrastructure now to strengthen U.S. preparedness for the future. These investments in surveillance, in vaccines and therapies, and in One Health coordination will safeguard Americans from many more emerging threats than just H5N1 or influenza, generating tools and playbooks that will be needed for future emergencies.

This is a moment of vulnerability for the United States, as the new year will bring a transition in U.S. leadership in the presidency, Congress, and federal agencies.

Viruses continue to circulate during periods of both political turbulence and stability. Public health officials at all levels of government have the responsibility to ensure that the national response to emerging threats such as H5N1 remains a priority.

This report is made possible by the generous support of the Bill & Melinda Gates Foundation.