America’s Infectious-Disease Barometer Is Off

The ongoing outbreak of H5N1 avian flu virus looks a lot like a public-health problem that the United States should be well prepared for.

Although this version of flu is relatively new to the world, scientists have been tracking H5N1 for almost 30 years. Researchers know the basics of how flu spreads and who tends to be most at risk. They have experience with other flus that have jumped into us from animals. The U.S. also has antivirals and vaccines that should have at least some efficacy against this pathogen. And scientists have had the advantage of watching this particular variant of the virus spread and evolve in an assortment of animals—including, most recently, dairy cattle in the United States—without it transmitting in earnest among us. “It’s almost like having the opportunity to catch COVID-19 in the fall of 2019,” Nahid Bhadelia, the founding director of Boston University Center on Emerging Infectious Diseases, told me.

Yet the U.S. is struggling to mount an appropriate response. Because of the coronavirus pandemic, the nation’s alertness to infectious disease remains high. But both federal action and public attention are focusing on the wrong aspects of avian flu and other pressing infectious dangers, including outbreaks of measles within U.S. borders and epidemics of mosquito-borne pathogens abroad. To be fair, the United States (much like the rest of the world) was not terribly good at gauging such threats before COVID, but now “we have had our reactions thrown completely out of whack,” Bill Hanage, an infectious-disease epidemiologist and a co-director of the Center for Communicable Disease Dynamics at Harvard’s School of Public Health, told me. Despite all that COVID put us through—perhaps because of it—our infectious-disease barometer is broken.

H5N1 is undoubtedly concerning: No version of this virus has ever before spread this rampantly across this many mammal species, or so thoroughly infiltrated American livestock, Jeanne Marrazzo, the director of the National Institute of Allergy and Infectious Diseases, told me. But she and other experts maintain that the likelihood of H5N1 becoming our next pandemic remains quite low. No evidence currently suggests that the virus can spread efficiently between people, and it would still likely have to accumulate several more mutations to do so.

That’s been a difficult message for the public to internalize—especially with the continued detection of fragments of viral genetic material in milk. Every expert I asked maintained that pasteurized dairy products—which undergo a heat-treatment process designed to destroy a wide range of pathogens—are very unlikely to pose imminent infectious threat. Yet the fear that dairy could sicken the nation simply won’t die. “When I see people talking about milk, milk, milk, I think maybe we’ve lost the plot a little bit,” Anne Sosin, a public-health researcher at Dartmouth, told me. Experts are far more worried about still-unanswered questions: “How did it get into the milk?” Marrazzo said. “What does that say about the environment supporting that?”

During this outbreak, experts have called for better testing and surveillance—first of avian and mammalian wildlife, now of livestock. But federal agencies have been slow to respond. Testing of dairy cows was voluntary until last week. Now groups of lactating dairy cows must be screened for the virus before they move across state lines, but by testing just 30 animals, often out of hundreds. Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told me he would also like to see more testing of other livestock, especially pigs, which have previously served as mixing vessels for flu viruses that eventually jumped into humans. More sampling would give researchers a stronger sense of where the virus has been and how it’s spreading within and between species. And it could help reveal the genomic changes that the virus may be accumulating. The U.S. Department of Agriculture and other federal agencies could also stand to shift from “almost this paternalistic view of, ‘We’ll tell you if you need to know,’” Osterholm said, to greater data transparency.  (The USDA did not respond to a request for comment.)

Testing and other protections for people who work with cows have been lacking, too. Many farm workers in the U.S. are mobile, uninsured, and undocumented; some of their employers may also fear the practical and financial repercussions of testing workers. All of that means a virus could sicken farm workers without being detected—which is likely already the case—then spread to their networks. Regardless of whether this virus sparks a full-blown pandemic, “we are completely ignoring the public-health threat that is happening right now,” Jennifer Nuzzo, the director of the Pandemic Center at the Brown University School of Public Health, told me. The fumbles of COVID’s early days should have taught the government how valuable proactive testing, reporting, and data sharing are. What’s more, the pandemic could have taught us to prioritize high-risk groups, Sosin told me. Instead, the United States is repeating its mistakes. In response to a request for comment, a CDC spokesperson pointed me to the agency’s published guidance on how farmworkers can shield themselves with masks and other personal protective equipment, and argued that the small number of people with relevant exposures who are displaying symptoms has been adequately monitored or tested.

Other experts worry that the federal government hasn’t focused enough on what the U.S. will do if H5N1 does begin to rapidly spread among people. The country’s experience with major flu outbreaks is an advantage, especially over newer threats such as COVID, Luciana Borio, a former acting chief scientist at the FDA and former member of the National Security Council, told me. But she worries that leaders are using that notion “to comfort ourselves in a way that I find to be very delusional.” The national stockpile, for instance, includes only a limited supply of vaccines developed against H5 flu viruses. And they will probably require a two-dose regimen, and may not provide as much protection as some people hope, Borio said. Experience alone cannot solve those challenges. Nor do the nation’s leaders appear to be adequately preparing for the wave of skepticism that any new shots might meet. (The Department of Health and Human Services did not respond to a request for comment.)

In other ways, experts told me, the U.S. may have overlearned certain COVID lessons. Several researchers imagine that wastewater could again be a useful tool to track viral spread. But, Sosin pointed out, that sort of tracking won’t work as well for a virus that may currently be concentrated in rural areas, where private septic systems are common. Flu viruses, unlike SARS-CoV-2, also tend to be more severe for young children than adults. Should H5N1 start spreading in earnest among humans, closing schools “is probably one of the single most effective interventions that you could do,” Bill Hanage said. Yet many politicians and members of the public are now dead set on never barring kids from classrooms to control an outbreak again.

These misalignments aren’t limited to H5N1. In recent years, as measles and polio vaccination rates have fallen among children, cases—even outbreaks—of the two dangerous illnesses have been reappearing in the United States. The measles numbers are now concerning and persistent enough that Nahid Bhadelia worries that the U.S. could lose its elimination status for the disease within the next couple of years, undoing decades of progress. And yet public concern is low, Helen Chu, an immunologist and respiratory-virus expert at the University of Washington, told me. Perhaps even less thought is going toward threats abroad—among them, the continued surge of dengue in South America and a rash of cholera outbreaks in Africa and southern Asia. “We’re taking our eye off the ball,” Anthony Fauci, NIAID’s former director, told me.

That lack of interest feels especially disconcerting to public-health experts as public fears ignite over H5N1. “We don’t put nearly enough emphasis on what is it that really kills us and hurts us,” Osterholm told me. If anything, our experience with COVID may have taught people to further fixate on novelty. Even then, concern over newer threats, such as mpox, quickly ebbs if outbreaks become primarily restricted to other nations. Many people brush off measles outbreaks as a problem for the unvaccinated, or dismiss spikes in mpox as an issue mainly for men who have sex with men, Ajay Sethi, an infectious-disease epidemiologist at the University of Wisconsin at Madison, told me. And they shrug off just about any epidemic that happens abroad.

The intensity of living through the early years of COVID split Americans into two camps: one overly sensitized to infectious threats, and the other overly, perhaps even willfully, numbed. Many people fear that H5N1 will be “the next big one,” while others tend to roll their eyes, Hanage told me. Either way, public trust in health authorities has degraded. Now, “no matter what happens, you could be accused of not sounding the alarm, or saying, ‘Oh my God, here we go again,’” Jeanne Marrazzo told me. As long as infectious threats to humanity are growing, however, recalibrating our sense of infectious danger is imperative to keeping those perils in check. If a broken barometer fails to detect a storm and no one prepares for the impact, the damage might be greater, but the storm itself will still resolve as it otherwise would. But if the systems that warn us about infectious threats are on the fritz, our neglect may cause the problem to grow.