In 2005, U.S. President George W. Bush stood at a lectern in Bethesda, Maryland, to make an important announcement. He was joined by five members of his cabinet, two senators, three congressmen, and multiple international guests. It was an unusual show of force for a press conference, and with two unpopular wars underway and the response to Hurricane Katrina still floundering, there was plenty else to attend to.
“Leaders at every level of government have a responsibility to confront dangers before they appear and engage the American people on the best course of action”, he declared. A failure to do so, he said, could cost millions of lives and trillions of dollars. Bush then announced a sweeping new program meant to tackle those dangers head-on.
But it wasn’t a military conflict that commanded presidential attention. It wasn’t another hurricane or a terrorist attack. It was influenza.
“Pandemic flu”, Bush explained, “occurs when a new strain of influenza emerges that can be transmitted easily from person to person—and for which there is little or no natural immunity”. No such strain existed then, but Bush was worried that one soon might. To that end, he was announcing the creation of the National Strategy for Pandemic Influenza, a comprehensive government plan for handling pandemic flu outbreaks. “By preparing now, we can give our citizens some peace of mind”, he said.
His warning proved prescient. Four years later, in 2009, two children in southern California with no connection to each other developed fevers and coughs. Laboratory tests soon revealed that they were both infected with a new subtype of influenza. Within two weeks, the Centers for Disease Control and Prevention activated its Emergency Operations Center and began work to develop a vaccine. The Strategic National Stockpile sent antivirals and personal protective equipment to states. The World Health Organization declared a “Public Health Emergency of International Concern” and raised the influenza pandemic alert to the highest level. The H1N1 pandemic had begun.
Now, 14 years after H1N1, and with COVID-19 still roiling the world, the United States is again facing the prospect of an influenza pandemic. Avian influenza, or H5N1, has been tearing through animals for over a year, spreading more widely than it ever has before. In the United States, H5N1 has been detected in more than 6,300 wild birds and in every state. Outbreaks in commercial flocks have been registered in 47 states, leading farmers to cull over 58 million birds. It has been found in American mammals, such as raccoons and harbor seals. And the number of affected birds and mammal species continues to grow.
Yet this time, there is little evidence of the tenacity that propelled action in 2005 and 2009. Instead, the world has largely chosen to wait and see what happens next. It is a dangerous proposition. Thus far, although H5N1 has rarely infected humans, among the cases that have been diagnosed, the fatality rate has been roughly 50 percent. A bird flu that spreads efficiently among people would result in a new pandemic and exact extraordinary costs to human life, society, and the global economy.
The United States needs to make sure it is ready for such a pandemic—just in case it happens. It can start by updating evaluations of how likely H5N1 is to start spreading between humans and what effect such spread would have. It should identify and prepare emergency steps to control the virus, should it mutate. The country also needs to look at the existing vaccines it has for the avian flu to see if they are effective, and it must review its distribution plans. It has to restock whatever health supplies it burned through while fighting COVID-19. And it must communicate all these steps to the U.S. population. Otherwise, the United States risks finding itself mired in another catastrophic pandemic.
NO CHICKEN LITTLE
Although it has attracted relatively little public attention, the scope of the avian flu outbreak is far beyond anything the world has seen before. The World Organization for Animal Health has recorded hundreds of H5N1 outbreaks in dozens of countries. In January 2023 alone, the organization recorded 70 outbreaks across three continents, resulting in the culling of three million birds in a three-week reporting period.
Infections have also been reported in a variety of mammals, including skunks, foxes, bobcats, bears, mountain lions, and a tiger. For scientists, these cases are particularly alarming. The influenza virus is notorious for its propensity to adapt, mutate, and combine with other influenza viruses to form new subtypes. Its versatility and long track record of driving pandemics are the principal reasons why influenza has long been ranked as the top infectious disease risk. The fact that the virus is already infecting various mammals raises the possibility that H5N1 could gain the ability to spread between humans.
A recent study out of Spain snapped the plausibility of this scenario into focus. Most mammal infections with the virus are one-offs, acquired when an animal has direct contact with a bird. (A fox, for example, could pick it up by scavenging a carcass.) But in Spain, investigators observed a more concerning pattern. Mink in a commercial farming facility became ill with H5N1 even though no poultry outbreaks had been reported in the region. A subsequent investigation led epidemiologists to conclude that the virus was likely spreading among the animals. Mink can become infected with both avian and human influenza viruses, which suggests they could serve as vessels for the virus to learn how to spread between people.
Mink are not the only mammals that may have experienced internal H5N1 transmission. Peruvian health officials reported in March that tens of thousands of wild birds and nearly 3,500 sea lions were found dead off the country’s coast, all infected with the avian flu. The sea lions may all have had direct contact with infected birds and encountered the virus that way. But given the size of the die-off, it is possible that the virus was spreading among the mammals themselves. A rapid investigation by veterinary health officials was unable to rule out that possibility.
To be clear, the mink and possible sea lion outbreaks are not themselves catalytic events that would make H5N1 a human threat. Both ended without infecting people, and the mink bout was thoroughly controlled by Spanish health authorities. But they are teachable moments, shots over the bow that show how the virus might find a path to spread in humans.
READY TO ROLL
There are multiple ways that the avian flu could evolve. The virus could remain primarily a threat to animal health until it recedes, as it has in the past. It could also stay limited to animals without routinely infecting humans, becoming a persistent ecological and economic threat, including by driving up egg and poultry prices and threatening endangered species. But the third scenario, and the one of greatest concern, is that H5N1 could evolve to spread efficiently between people.
It is impossible to say which of these scenarios will come to pass, and overreacting risks wasting public attention and resources. In the wake of the 2001 anthrax attacks, for example, concerns about future acts of bioterrorism motivated the United States to offer smallpox vaccines to health-care workers and emergency responders. But the vaccine in use at the time was fairly risky, and smallpox attacks were a theoretical concern, so the program was stymied by low participation. Ultimately, the federal government spent important political capital on something unpopular.
But an even worse failing would be to underreact to the next emerging threat, especially given the stakes. Policymakers therefore must take steps to prepare for a human H5N1 pandemic. That way, if one does emerge, the country can respond swiftly and aggressively.
The most important immediate action that governments can take is to better gauge exactly how likely it is that bird flu will efficiently spread between humans. The Centers for Disease Control and Prevention uses a standardized Influenza Risk Assessment Tool that is meant to do just that. But the agency has not updated it for H5N1 since March 2022—before the recent explosion of cases, and before scientists gained a greater understanding of the virus. The tool should be updated now and more frequently going forward, at least until this animal epidemic ends.
The federal government should also establish metrics and triggers for when to escalate its public health response to H5N1. During previous public health crises, officials lost time negotiating over when such a response is justified. During the 2014 to 2016 outbreak of the Ebola virus in West Africa, the international public health community infamously took months to rally because it falsely assumed the outbreak would easily come under control. The result was an outbreak that spread across the region and took 11,325 lives. To avoid repeating that error with H5N1, officials should hold discussions now with the goal of identifying clear and agreed-upon indicators for when to initiate certain emergency actions—for example, if multiple human cases are diagnosed within a short period. Relatedly, government departments and agencies with pandemic management responsibilities should explain clearly and in great detail what those emergency actions will be. The U.S. Department of Health and Human Services, for example, might revisit its Pandemic Influenza Plan to incorporate lessons learned from the COVID-19 pandemic. (The plan was last updated in 2017.)
Officials should also begin preparing public health actions—especially for how they will produce and distribute vaccines. Here, unlike with COVID-19, the United States will not have to start from scratch: the Pandemic Influenza Stockpile contains a vaccine designed to protect against H5N1. But the government must make sure this vaccine has been tested against the currently circulating strain. It must also determine whether it needs new investments to scale up vaccine production, and it should check plans to distribute doses. Right now, the vaccine is likely stored in bulk form to extend its shelf life. To be usable, the doses would instead need to be “filled and finished”—in other words, put into vials—a possibly time-consuming process that the government should map out. Finally, the United States must examine its Strategic National Stockpile. It usually holds materials necessary for successful mass vaccination campaigns, such as syringes, but its stores may have been drawn down by the government’s responses to COVID-19 and mpox (formerly known as monkeypox). If the government does not have enough of these materials, it needs to rapidly replenish them now.
Finally, the federal government should increase its communications regarding the H5N1 situation and the measures it is taking to prepare. Right now, there is very little information available in the public domain, a misstep that echoes the early days of the COVID-19 and mpox epidemics. As both outbreaks have shown, information voids are inevitably filled with misinformation, whether maliciously spread or not. The United States should not let that happen again.
None of this will be easy. Washington may face even greater competing crises today than in 2005, when Bush launched the country’s influenza strategy. But it also has the institutional and public memory of the COVID-19 pandemic, which can work to its advantage. And critically, it still has time. If Washington uses this opportunity right, the United States can be well prepared for a scenario where H5N1 becomes a human virus.
Caitlin Rivers is Senior Scholar at the Johns Hopkins Center for Health Security and an Assistant Professor at the Johns Hopkins Bloomberg School of Public Health. From 2021 to 2022, she served as founding Associate Director of the Center for Forecasting and Outbreak Analytics at the Centers for Disease Control and Prevention.