Pandemic Center

California health officials reported Tuesday that a child in Alameda County tested positive for H5 bird flu last week.

The source of infection is not known — although health officials are looking into possible contact with wild birds — and the child is recovering at home with mild upper respiratory symptoms.

Health officials have confirmed the "H5" part of the virus, not the "N1." There is no human "H5" flu; it is only associated with birds.

The child was treated with antiviral medication, and the sample was sent to the U.S. Centers for Disease Control and Prevention for confirmatory testing.

The initial test showed low levels of the virus and, according to the state health agency, testing four days later showed no virus.

"The more cases we find that have no known exposure make it difficult to prevent additional" infections, said Jennifer Nuzzo, professor of epidemiology and director of the Brown University School of Public Health's Pandemic Center. "It worries me greatly that this virus is popping up in more and more places and that we keep being surprised by infections in people whom we wouldn't think would be at high risk of being exposed to the virus."

Read more: Canadian teenager infected with H5N1 bird flu in critical condition

A statement from the California Department of Public Health said that none of the child's family members have the virus, although they, too, had mild respiratory symptoms. They are also being treated with antiviral medication.

The child attended a day care while displaying symptoms. People the child may have had contact with have been notified and are being offered preventative antiviral medication and testing.

“It’s natural for people to be concerned, and we want to reinforce for parents, caregivers and families that based on the information and data we have, we don’t think the child was infectious — and no human-to-human spread of bird flu has been documented in any country for more than 15 years,” said CDPH Director and State Public Health Officer Dr. Tomás Aragón.

The case comes days after the state health agency announced the discovery of six new bird flu cases, all in dairy workers. The total number of confirmed human cases in California is 27. This new case will bring it to 28, if confirmed. This is the first human case in California that is not associated with the dairy industry.

The total number of confirmed human cases in the U.S., including the Alameda County child, now stands at 54. Thirty-one are associated with dairy industry, 21 with the poultry industry, and now two with unknown sources.

In Canada, a teenager is in critical condition with the disease. The source of that child's infection is also unknown.

Genetic sequencing of the Canadian teenager's virus shows mutations that may make it more efficient at moving between people. The Canadian virus is also a variant of H5N1 that has been associated with migrating wild birds, not cattle.

Genetic sequencing of the California child's virus has not been released, so it is unclear if it is of wild bird origin, or the one moving through the state's dairy herds.

In addition, WastewaterScan — an infectious disease monitoring network led by researchers from Stanford University and Emory University, with laboratory support from Verily, Alphabet Inc.’s life sciences organization — follows 28 wastewater sites in California. All but six have shown detectable amounts of H5 in the last couple of weeks.

There are no monitoring sites in Alameda Co., but positive hits have been found in several Bay Area wastewater districts, including San Francisco, Redwood City, Sunnyvale, San Jose and Napa.

"This just makes the work of protecting people from this virus and preventing it from mutating to cause a pandemic that much harder," said Nuzzo.

For years, Robert F. Kennedy Jr., has leveraged his famous name, his celebrity connections and his nonprofit, Children’s Health Defense, to spread misinformation about vaccines and call their safety and efficacy into question. Soon, he might have the power to go much further.

If Mr. Kennedy is confirmed by the Senate to be secretary of health and human services, he would be in charge of the nation’s pre-eminent public health and scientific agencies, including those responsible for regulating vaccines and setting national vaccine policy.

Legal and public health experts agree that he would not have the authority to take some of the most severe actions, such as unilaterally banning vaccines, which Mr. Kennedy has said he has no intention of doing.

“I’m not going to take anyone’s vaccines away from them,” he wrote on social media last month. “I just want to be sure every American knows the safety profile, the risk profile, and the efficacy of each vaccine.”

But Mr. Kennedy, who has said that he wants federal researchers to pull back from studying infectious diseases, could exert his influence in many other ways. His actions could reduce vaccination rates, delay the development of new vaccines and undermine public confidence in a critical public health tool.

In the last three decades alone, childhood vaccines have prevented more than 500 million cases of disease, 32 million hospitalizations and more than one million deaths in the United States, according to a recent report from the Centers for Disease Control and Prevention. But vaccination rates have been falling in recently years, and Mr. Kennedy could accelerate the trend, public health experts said.

“A lot of damage is possible,” said Dr. Thomas Frieden, a former director of the C.D.C. who now leads Resolve to Save Lives, a public health nonprofit. “The secretary of health has a life-or-death responsibility. And if unscientific statements and decisions are made, if agencies are damaged, if public confidence is undermined, then you can get spread of disease.”

Here are five things Mr. Kennedy could do.

He could revise the government’s vaccine recommendations.
As the federal health secretary, Mr. Kennedy would oversee the C.D.C., the agency that issues guidance on which immunizations Americans should get and when.

Health insurers look to those recommendations to determine what vaccines to cover and state health departments use them to inform their own vaccine policies.

Mr. Kennedy would have final say over which experts sit on the external committee that advises the C.D.C. on vaccines, and he would be the boss of the C.D.C. director, who decides whether to adopt that guidance. “That’s, in my mind, a recipe for a disaster,” said Lawrence O. Gostin, an expert in public health law at Georgetown University.

A C.D.C. director or advisory committee that is hesitant toward vaccines could usher in changes in the childhood vaccine schedule, such as removing vaccines from the list of recommended immunizations or changing the ages at which they are advised.

“If the question is purely, could the H.H.S. secretary unilaterally remove vaccines from a schedule or alter the schedule, I think the answer to that would ultimately be no,” said Dr. Michael Mina, an epidemiologist and former professor at Harvard University. “But with a little bit of planning, through like-minded appointments and top-down pressure, the answer to that starts to move the needle toward yes.”

One thing he could not do is abolish vaccine mandates, such as requirements that children receive certain immunizations before attending school. Those are set by state and local governments. The federal health secretary does not have the authority to override them.

But some public health experts fear that some state health authorities, particularly in Republican-led states, could follow a C.D.C. that is skeptical of vaccines. One result might be lower vaccination rates — and worse public health outcomes — in red states than in blue ones, Mr. Gostin said, similar to the pattern that played out with the Covid-19 vaccines.

He could slow vaccine development and approval.
Mr. Kennedy would also be in charge of the F.D.A., the agency responsible for approving new vaccines.

He has repeatedly criticized the agency, which fast-tracked the authorization of the Covid-19 vaccines, as well as the shots themselves. As health secretary, he would not be able to remove them or any other already authorized vaccines from the market without strong scientific evidence, Mr. Gostin said. If he tried, vaccine manufacturers could sue over such a decision and courts would most likely rule in their favor, he said.

But he could bring people who share his views into the F.D.A. Together, they could make the process for approving new vaccines more onerous and lengthy, including requiring more data.

“He could say, ‘I don’t think this has been studied in the right way,’” said Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia and an adviser to the F.D.A.

He could also stop or slow vaccine development research conducted at or funded by the National Institutes of Health, the federal government’s top medical research agency, which would also fall under his purview. He has been clear about his plans to empty some divisions that focus on advancing vaccine research and development. He has said he would fight the next pandemic instead by “building people’s immune systems.”

“I’m going to say to N.I.H. scientists, ‘God bless you all,’” Mr. Kennedy said as a presidential candidate last November. “‘Thank you for public service.’ We’re going to give infectious disease a break for about eight years.”

Infectious diseases are still looming, however. And a slowdown in vaccine research, development or approval could have particularly dire consequences in the event of another public health emergency like Covid-19.

Bird flu, for instance, continues to infect American farm workers, and experts have worried that the virus could evolve to spread more easily among humans. If that happened, “we would be in a new pandemic,” said Jennifer Nuzzo, the director of the Pandemic Center at Brown University. “And that pandemic would move very quickly. Any attempt to not act with urgency would be deadly.”

He could emphasize vaccine side effects.
Decades of scientific study confirm that the benefits of vaccines far outweigh the risks, but like all medications, they carry the possibility of side effects, including some rare but serious ones. Mr. Kennedy — who has said he wants more public visibility into safety data — is poised to draw outsize attention to adverse outcomes.

His nonprofit promotes a database of research that includes hundreds of misleading interpretations of vaccine data. In September, the group released “Vaxxed 3: Authorized to Kill,” a film claiming that Covid vaccines led to “tragic outcomes of either death or serious injury.”
Under Mr. Kennedy, federal agencies like the F.D.A. could highlight potential side effects by requiring vaccine makers to list even very rare ones on the packaging label.

Mr. Kennedy could also draw attention to unverified reports of adverse events collected by federal agencies. “What I would worry about is an abuse of the data,” said Dr. Peter Lurie, the president of the Center for Science in the Public Interest and a former associate commissioner at the F.D.A.

Mr. Kennedy could also push federal agencies to conduct more research into vaccine safety. That would not be a bad thing in itself, said Dr. Ofer Levy, director of the precision vaccines program at Boston Children’s Hospital and an adviser to the F.D.A. “There is more research that can be done, particularly on some of the newer vaccines,” he said.

But, the research must be scientifically rigorous, he added, and build upon decades of scientific evidence related to vaccine safety. “If you signal this to the public as, ‘Well, we have to start from scratch, all of these vaccines are suspect,’ I would disagree with that approach,” Dr. Levy said. “Because many of these vaccines have been very, very well studied, and they’re a huge win for kids.”

He could weaken legal protections for vaccine makers.
Under a longstanding federal law, people who experience serious side effects after receiving certain routine vaccinations are limited in their ability to sue drug companies. Instead, they can seek compensation through a government-run program. The law is intended to encourage drug companies to invest in vaccine development.

Mr. Kennedy could not make major changes to the law without congressional approval, but he could remove specific vaccines from the program. Whether he could take every vaccine off the list is “difficult to say, because it’s uncharted waters, legally speaking,” said Ana Santos Rutschman, an expert on health law and policy at Villanova University.

If vaccines are removed from the program, some companies may decide to stop making them. “And that’s going to have two effects: driving vaccine costs up and reducing availability for those who want the vaccines,” said Dorit Reiss, an expert on vaccine policy and law at the University of California College of the Law, San Francisco.

(And because the program is more favorable to plaintiffs than the courts are, paring down the list could actually make it more difficult for people with vaccine injuries to be compensated, Dr. Reiss added.)

A more recent law also provides liability protections to companies making vaccines for public health emergencies, such as the Covid-19 pandemic. These protections are put in place by a declaration from the secretary of health; in the event of another pandemic, Mr. Kennedy could simply refrain from making one.

Over the longer term, experts said, weakening the liability protections would probably prompt some pharmaceutical companies to abandon vaccine development. “Which, from a public health perspective, may mean fewer vaccines in the future,” Ms. Rutschman said.

He could speak out against vaccines.
Many experts say they worry most about Mr. Kennedy’s bully pulpit. If confirmed, Mr. Kennedy would have a new platform for spreading misinformation about vaccines and amplifying fears about their safety.

“It’s very hard to claw back outrageous ideas when social media algorithms propel them forward,” Dr. Nuzzo said.

Vaccine hesitancy grew during Mr. Trump’s first term as president and persisted after he left office.

Vaccine experts have said that Mr. Kennedy is particularly skilled at taking good, peer-reviewed science and skewing the findings.

Dr. Mina said he expected Mr. Kennedy to “to do exactly what he’s been doing for years: fudging the way that data is meant to be interpreted, using very manipulative tactics to drive a message that makes vaccines look dangerous. He is a master at it — truly a master.”

During a measles outbreak in Samoa in 2019, Mr. Kennedy stoked the skepticism driving the spread. He wrote to the nation’s prime minister on the Children’s Health Defense letterhead, suggesting that the failure of vaccines given to pregnant women and children was the true culprit. More than 50 children died in the outbreak.

RFK Jr. is ‘exactly the wrong pick’ for HHS secretary

Dr. Jennifer Nuzzo, director of Brown University’s Pandemic Center, criticizes President-elect Donald Trump's pick for Health and Human Services secretary.

November 15, 2024

Canadian health officials announced Tuesday that a teenager infected with H5N1 bird flu from an unknown source is in critical condition.

According to British Columbia Provincial Health Officer Bonnie Henry, the child is suffering from acute respiratory distress and was hospitalized on Friday.

The teen is the first presumptive case of H5N1 bird flu in Canada.

“Our thoughts continue to be with this person and their family,” said Henry.

Authorities believe the virus was acquired via an animal source; however, the teen was not on a farm nor near any known wild birds or backyard poultry — common reservoirs for the disease.

According to a CBC interview with Henry, the teen did not have any contact with birds but did interact with a variety of other animals — including a dog, cats and reptiles — in the days before becoming ill. Testing on those animals has so far been negative.

The health authorities are also tracing people the teen was in contact with; so far they have not identified other infections.

The situation is “horrifying,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University. “The idea that we have a child, a teenager, who is seriously ill from this virus is just really an utter tragedy. But sadly, it’s not surprising, given everything we’ve known about H5N1 and its potential to cause illness.”

She noted that since the late 1990s, when this current strain of bird flu originated in China’s Guangdong province, the fatality rate was close to 60%. That number is likely inflated, she said, as presumably most people tested for the disease were those who went to hospitals or clinics to seek treatment; people who had mild symptoms, or were asymptomatic, were likely not tested.

Nevertheless, Nuzzo said, while this virus could “be a lot less deadly than what we’ve seen to date,” it could still be far more deadly than any pandemic we’ve seen in a long time, including COVID.

She said the case causes her concern for three reasons: The first is the severity of the teen’s illness. The second is that “we don’t understand how the teenager got infected,” she said. Her third concern is how government officials are dealing with this outbreak, which she described as “letting it continue to spread from animals to people, without trying to do more to get ahead of it.”

She said the virus may in the end not end up becoming more virulent or efficient at moving between people, “but I don’t think we want to wait around and on the chance that it might.”

Since the virus appeared in North American wild birds in 2021, human cases have mostly presented as mild. Since 2022, there have been 47 human cases in the U.S. — 25 in dairy workers, 21 in poultry workers, and one case in Missouri where the source has not yet been identified.

However, a recent study from the U.S. Centers for Disease Control and Prevention shows the virus is more widespread in dairy workers than had previously been assumed. An examination of antibodies in 115 dairy workers from Michigan and Colorado showed that eight people were positive for the disease, or 7% of the study population — indicating that either workers were not reporting illness, or they were asymptomatic.

Nuzzo also pointed to a recent study published in Nature, led by Yoshihiro Kawaoka, an H5N1 expert at the University of Wisconsin, in Madison, that showed the virus that infected the first reported dairy worker in Texas had acquired mutations that made it more severe in animals as well as allowing it to move more efficiently between them — via airborne respiration.

When Kawoaka exposed ferrets to this viral isolate, 100% died. In addition, the amount of virus they were initially exposed to didn’t seem to matter. Even very low doses caused mortality.

Kawoaka told The Times in an interview that the mutations seen in this particular isolate have appeared elsewhere in past outbreaks in birds and mammals, “so in that sense, it’s a very orthodox mutation.”

On Wednesday, Canadian health authorities announced they had genetically sequenced the virus in the teen, and it is the newer D1.1 version that has affected poultry flocks in the Pacific Northwest this fall, and was likely carried by wild birds migrating south. It is not the version being seen in dairy cows or dairy workers, which has been called B3.13. Both are of the H5N1 2.3.4.4b clade that has been wreaking havoc across North and South America since 2021, and in Europe, Asia and Africa since 2020.

Fortunately, the mutated isolate that infected the lone dairy worker in Texas has not been seen since. It’s unclear why the worker did not present with more severe symptoms.

However, there are a few hypotheses.

Kawaoka’s research shows “inefficient replication” of the virus in human corneal cells. If the worker was exposed by a splash of contaminated milk to the eye, or a rub of the eye with a contaminated glove, the virus may have been stalled out — unable to replicate like it could have had the worker been exposed via inhalation.

Nuzzo said there are other hypotheses — which she stressed are just hypotheses — including one that posits people who were exposed to the H1N1 swine flu outbreak in 2009 may have acquired some immunity to the “N1” part of the virus.

The other goes back to a person’s first influenza exposure.

There is a scientific hypothesis called the “original antigenic sin” that suggests that a person’s first exposure to a particular virus “may sort of kind of set the tone” for that person’s immune system going forward — so this worker’s first flu exposure may have provided his immune system with the defenses needed to suppress H5N1.

“There are a lot more questions than answers at this point. So there are a lot of interesting hypotheses for why the more recent cases have been mild, there’s not enough evidence to simply discard more than two decades worth of evidence about this virus that tells us that it could be quite deadly,” said Nuzzo.

As human flu season ramps up, Nuzzo said it’s critically important that people do what they can to prevent the spread of disease.

She said both seasonal flu and H5N1 vaccines should be provided to dairy workers.

Unfortunately, she said, “our surveillance efforts for trying to find outbreaks on farms, while getting better, are still not even close to what we need to know about these outbreaks.”

In the meantime, vaccines and antiviral medications need to be on hand.

“The news of a deeply serious human case of bird flu is a massive wake-up call that should immediately mobilize efforts to prevent another human pandemic,” said Farm Forward Executive Director Andrew deCoriolis. “We could have prevented the spread of bird flu on poultry farms across America, and we didn’t. We could have prevented the spread of bird flu on dairy farms, and we didn’t.”

“Factory farms notorious for raising billions of sickly animals in filthy, cramped conditions provide a recipe for viruses like bird flu (H5N1) to emerge and spread,” said deCoriolis in a statement. “We are now on the cusp of another pandemic and the agencies responsible for regulating farms and protecting public health are moving slower than the virus is spreading.”

As of Wednesday, there have been 492 dairy herds infected with H5N1 across 15 states. More than half, 278, are in California. Two pigs in Oregon have also been infected.

A Canadian teenager is hospitalized in critical condition with bird flu, health officials reported Tuesday.

The teen has been receiving care at BC Children’s Hospital in Vancouver since Friday, the same day an initial test came back positive for H5 influenza. Government testing confirmed that the strain is H5N1, the Public Health Agency of Canada said Wednesday.

The young person’s first symptoms, which began a week before they were hospitalized, were conjunctivitis or red eyes, fever and cough, said Dr. Bonnie Henry, an epidemiologist who is the provincial health officer for British Columbia.

The illness has progressed to acute respiratory distress syndrome, or ARDS. People with ARDS typically need help breathing with machines such as a ventilator, but officials did not offer specifics on the teen’s treatment except to say they’re receiving antiviral medications.

This is the first known human case of bird flu acquired in Canada. The country had one case in 2014, which was travel-related, Henry said.

It is still unknown how the teen caught this strain of flu, which has been circulating widely in wild birds, poultry and some mammals, including cattle in North America since 2022.

“Because this is such a rare event and a sentinel event, it is important for us to do as thorough an investigation as possible, and we’re committed to doing that,” Henry said.

There have also been 46 confirmed human infections in the United States as part of the ongoing outbreak this year, mostly among farm workers tending infected animals. All those cases have been mild, and people who have tested positive have recovered from their illnesses after treatment with antiviral medications.

These cases have all been among adults, however, and Henry said it’s possible that the teen’s case is more severe because as a younger person, they’d had less exposure to seasonal strains of the flu, which may offer some degree cross-protection against H5 bird flu strains.

The teen, who was described as healthy before they caught the virus, began experiencing symptoms November 2. They went to an emergency room, were sent home and returned to the hospital a few days later when their condition got worse.

Canadian officials are following more than 40 people who had contact with the teen during their infectious period, which started two days before they began experiencing symptoms.

“I will also say that there are many other tests that are being done on a number of people across the province to try and really get an understanding of what’s happening here,” Henry said.

Officials have no other evidence of anyone else becoming ill after contact with the teen.

“We don’t see right now that there’s a risk of a lot of people being sick,” she said.

More than two dozen poultry farms in British Columbia have been affected by H5N1, Henry said. Since 2022, about 11 million birds have been destroyed, with most of them in British Columbia. Unlike in the US, H5N1 has not been detected dairy cattle or milk in Canada.

“We are looking very, very carefully at all potential animal exposures, bird exposures. There were other pets in the house, and there was contact with pets in other houses,” Henry said. The teen had contact with dogs, cats and reptiles, but none has tested positive for H5N1. Investigators have not identified any contact between the teen and birds.

“Right now, we have no specific source identified, but the testing is ongoing in partnerships with our veterinary colleagues, and we’ll be continuing that investigation very thoroughly,” she added.

The US Centers for Disease Control and Prevention says that the current public health risk remains low but that it’s continuing to monitor the outbreak.

“This is a tragic development. It is an unfortunately unsurprising development,” said Dr. Jennifer Nuzzo, who directs the Pandemic Center at the Brown University School of Public Health.

“I think there’s been a lot of wishful thinking about this virus, that it wouldn’t cause people to become severely ill, but that hope, really, I think, stands in contrast to several decades worth of data,” she said.

Since 2003, over 900 human cases of H5N1 have been reported to the World Health Organization. Slightly more than half have been fatal.

“What I think this absolutely underscores is that H5N1 is a very serious public health threat, and we need to be doing more to stay ahead of it, to prevent more people from becoming severely ill or die,” Nuzzo said.

Eight out of 115 dairy workers, or 7%, who worked with H5N1-infected cows in Michigan and Colorado have antibodies to bird flu, according to a new study from the US Centers for Disease Control and Prevention (CDC) – a rate significantly higher than known cases of the highly pathogenic virus, which means existing efforts are not protecting, diagnosing and treating people at risk, experts said.

It could become even harder to detect cases amid the fall migration of wild birds, the upcoming human flu season, and repercussions of the second Trump administration’s proposed policies to curtail public health and expand deportation of immigrants, who serve as the backbone of the agricultural workforce in the US.

The new survey from the CDC and state health departments looked at blood samples from people who worked with H5-infected cows in Michigan and Colorado between June to August 2024.

Out of the eight people who had previously undetected cases of the highly pathogenic bird flu, four remembered having symptoms, mostly conjunctivitis, and the other four did not recall having symptoms.

All eight workers were Spanish speakers who reported milking infected cows or cleaning milk parlors. None of them wore respirators, and less than half wore eye protection like goggles.

Notably, only one person said they had worked with infected cows, even though all of them were working with cows on farms with known infections – pointing to barriers in workers understanding the risks they face.

“It really speaks to the importance of more on-farm training around H5 as well as ways to protect from H5,” Demetre Daskalakis, director of the National Center for Immunization and Respiratory Diseases, told reporters on Thursday.

The news of cases that flew beneath the radar is “completely unsurprising”, said Jennifer Nuzzo, the director of the Pandemic Center and a professor of epidemiology at Brown University School of Public Health.

“When you test people at their place of work, and if the consequence of testing positive is that they have to stay home and possibly not earn an income, you should expect that people might not tell you if they’ve had symptoms. Also, everything we know about flu gives us the very strong suspicion that there would be asymptomatic infections,” Nuzzo said.


Until now, the CDC has recommended testing only people who report symptoms after having direct animal contact.

“We are not doing enough to make sure that we are protecting people from getting infected and certainly making sure that people who are infected get access to medicines that could potentially keep them from getting severely ill,” Nuzzo said.

The CDC is now bolstering measures to protect workers, including expanding recommendations to test farm workers who are exposed to the virus but don’t develop symptoms, and offering those workers access to flu antivirals.

“We in public health need to cast a wider net in terms of who is offered a test so that we can identify, treat and isolate those individuals,” Nirav Shah, the CDC’s principal deputy director, said on Thursday. Identifying cases and treating people helps to keep a mild infection from turning into a severe one – and it reduces the chances that the virus will spread onward among people.

“The less room we give this virus to run, the fewer chances it has to cause harm or to change,” Shah said. The agency is also improving guidance and education on the importance of personal protective equipment.

“Because we haven’t seen severe illness and deaths yet, I think there’s been some complacency around trying to control this virus, but I’ve always said we shouldn’t wait for farm workers to die before we take action to protect them,” Nuzzo said. “I just don’t think you should gamble with people’s lives like that.”

She believes existing stockpiles of H5N1 vaccines should be offered to farm workers, pending their authorization from regulatory agencies. Vaccines can help prevent severe illness, particularly among a population that may be hesitant to come forward with an illness that could jeopardize their job or even their ability to stay in the country.

“Just offer it for people who may want to protect themselves,” Nuzzo said. “This virus is not going away. This virus is going to represent an even greater threat to human health as it continues to find its way into more and more US farms.”

If the “moral imperative” to protect agricultural workers doesn’t move Americans, perhaps the economic effects of higher costs of milk, eggs and meat will, she said. “Nobody wants the cost of groceries to be any higher than they already are.”

So far, there have been 46 official cases of H5N1 diagnosed in people this year, more than half of which have been among dairy farmworkers. Another nine people have now been identified by blood testing, for a total of 55 people affected by bird flu in 2024.

Other influenza variants will soon begin circulation in people this fall, which raises the possibility of reassortment – a process where different flu variants combine and potentially gain worse attributes.

“By allowing this virus to circulate, we could give it a runway to develop the ability to more easily infect people, and crucially, to be able to spread easily between people,” Nuzzo said. “If the virus can do that, we will be in a new pandemic.”