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0:00
Sometime in the 1990s, an Indonesian crime lord named Ponten Ginting made a deal with a demon. He asked for wealth and power, and his wish was granted. But instead of paying up, he stiffed the demon. In 2006, though Ponten was already deceased, members of his family began to fall ill with a mysterious affliction. Local magical practitioners consulted the spirits, and their message was clear: it was time to pay the piper.
0:24
Seven members of the family, they said, would be claimed by the vengeful demon. Though some of them received state of the art hospital care, others distrusted medical authorities and sought out local ritual experts instead. After all, who was better at dealing with demons? But the medical authorities feared a different cause: H5N1 influenza. Bird flu. As some of the Gintings fled for the remote hills of Sumatra, responders raced to keep up,
0:45
isolating their contacts and testing for the presence of the virus. Only one of the Gintings had been closely exposed to infected birds. That meant this could be the big one: a strain of avian influenza that could spread from person to person. At the time, bird flu was known to kill up to 60% of those it infected. If the responders failed to contain the outbreak, a pandemic could claim the lives of one billion people. Fortunately, the outbreak fizzled.
1:08
Exactly seven of the Gintings died, just as predicted. The antiviral drug Tamiflu was distributed to the Gintings’ close contacts, but many of them declined to take it. To them, the demon explanation was sufficient. After all, no birds were obviously sick, and no one outside the Ginting family had fallen ill. Ponten had tampered with supernatural forces he should have left alone. It just made sense. The Gintings’ story tells us two things.
1:32
One, that people tend to act rationally according to their own beliefs – not according to what experts want them to do. And two, that the next flu pandemic is just one stroke of bad luck away. Seasonal flu alone kills half a million people every year. The next pandemic, if it’s H5N1, could kill many times that number. Bird flu is out there. In fact, it’s increasingly out there. While it’s impossible to know when and where a pandemic will begin,
1:55
bird flu is getting more and more chances to make it happen. Eventually, it’s going to figure it out. My name is Pardis Sabeti, and I’m a professor of infectious disease at Harvard University. Among other things, I study how to combat emerging infectious diseases, like bird flu. However we respond to H5N1, those tools will be the ones we have to use against the next pandemic flu, and the one after that. Will we vanquish bird flu, and everything that comes next?
2:16
Or will we be complacent and allow many millions to be lost? Here’s why bird flu is almost inevitable, and what we can do about it. [♪ INTRO]
2:29
The Ginting family believed that a demon was responsible for their illness. But if you’ll allow us a metaphor, maybe it’s not all that strange to think of the flu as a demon. One that’s out to get all of us. One that’s dogged us for much of recorded history, shifting its shape to strike in different forms. This demon is clever, so to outwit it, we need to understand how it operates. In the case of H5N1 avian flu,
2:52
we know exactly what needs to happen for it to become able to easily infect humans. Dr. Webby: This is a virus that's still very, very much a bird virus. So, you know, it's not a virus that certainly infects humans very well, doesn't transmit between humans. And so this virus has got to change. It's got to change in a way that switches it from preferring to replicating in birds to preferring to replicate in humans for a pandemic to occur.
3:17
Dr. Sabeti: That’s Dr. Richard Webby, a virologist and expert in host-microbe interactions at St. Jude Children’s Hospital. And because H5N1 is infecting more and more birds and animals every year, we also know that it’s getting more and more chances to achieve the changes it needs to easily infect humans. Dr. Gronvall: Viruses have lots of mutational options to them, and they produce a gazillion of themselves. And so they explore the full range of their genetic possibilities,
3:45
often in every infection that they have. And so, you know, we're basically giving them lots of shots on goal as we're giving them opportunities to, to infect people. Dr. Sabeti: That’s Dr. Gigi Gronvall, a professor at Johns Hopkins University and an expert in pandemic preparedness. We’ll be hearing more from both of these experts later. Basically, H5N1 is a problem because it’s… everywhere. It’s infecting wild birds on nearly every continent,
4:11
giving it lots of opportunities to cross over to humans. And when it does, it can be incredibly bad. So how did the demon get to this point? First, let’s look at its history. In the year 412 BCE, the father of medicine himself, Hippocrates, treated patients with symptoms of influenza. And it’s only picked up steam since then. The historical record is patchy for a long time after that, but the first recorded flu pandemic,
4:36
where the disease spreads over a wide area, likely occurred sometime in the 16th century. And since the start of the 20th century, we’ve had flu pandemics in 1918, 1957, 1968, and 2009. In other words, we’re under regular assault by this demon. And the H5N1 flu virus is one of its most frightening faces. Every flu virus has eight genes – a crack team of eight minions, each with their own specialty. Whenever you hear flu referred to as H-number-N-number,
5:06
that’s in reference to two of its key minions: hemagglutinin and neuraminidase. Hemagglutinin is the most important one for our purposes today. It’s the team’s safecracker. It recognizes a type of sugar molecule on the surface of cells, called sialic acid, and uses that to break the virus in. In the normal seasonal flu you might get, the safecracker is either H1 or H3. Both are experts in breaking and entering in human cells. H5 specializes in infiltrating bird cells.
5:33
If it stays that way, that’s good for us, albeit not great for birds. Dr. Webby: One of the biggest host range barriers between avian hosts and human hosts is the sugars that this virus likes to bind to. So it's a virus that's got to get inside a cell to replicate. Flu viruses bind to a sialic acid sugar on the surface of the cell. They bind to that and then that gets the virus inside the cell. In avian hosts, that particular sialic acid is in
6:01
a slightly different form than what is most common in humans. Dr. Sabeti: Basically, a slight chemical difference between bird cell sugars and human cell sugars is what keeps H5N1 out. If H5 ever learns the trick to consistently breaking in using human sugars instead, we’re in for a bad time. Our immune systems have seen H1 and H3 before, and they know what to do. But almost no one’s immune system has ever met an H5 – as far as we know.
6:28
But every once in a while, H5 can – just barely – get its foot in the door. Let me show you what happens when it does. But as a warning, we’ll be talking about the death of a young child. Sometime around 1996 in southern China, the influenza virus learned to take on a new form in birds. In 1997, a three-year-old boy named Lam Hoi-Ka played with some baby birds at a school in Hong Kong. Did your kindergarten teacher ever bring in an incubator and let you watch baby chicks hatch?
6:54
It might have been something like that. Five days later, the child was dead. His lungs were ravaged – but so were his kidneys, his liver, and even his blood. As far as we know, he was the first human victim of H5N1 avian flu. Authorities raced to find the cause, but when they did, they couldn’t believe their eyes. Bird flu wasn’t supposed to infect humans. It wasn’t supposed to be possible. Yet more cases began to spring up. In total, eighteen infections would be detected, with six dead.
7:18
Eventually, the authorities ordered a drastic step. Dr. Webby: That particular virus was probably born within the live poultry markets in Hong Kong. It was born within those systems, within the chickens and ducks and other species in those markets. So, when the authorities in Hong Kong decided to depopulate all of those birds, they got rid of that particular form of the H5 virus. Unfortunately, the precursors and close cousins of that virus were still circulating in southern China.
7:48
Dr. Sabeti: That is to say – killing virtually all of Hong Kong’s poultry stopped the 1997 outbreak, but it didn’t destroy the demon virus at its source. It would strike again. So, why was this first outbreak so scary? It’s not just that our immune systems don’t know what to do with H5. It’s that so far, by flu standards, H5 is especially deadly and causes especially severe disease. Beginning with the 1997 outbreak, H5N1 has had a case fatality rate as high as 60% – that is,
8:16
60% of cases detected resulted in death. Keep that figure in mind, though, because we’re going to need it later. If you extrapolate that number to a global pandemic, and if you assume that the virus doesn't get milder as it gets better at jumping between humans, you end up with the unimaginable global crisis of 1 billion people dead. Now, that is a hair-on-fire, worst-case scenario for a few reasons. One, the case fatality rate can’t account for infections that aren’t detected,
8:41
and there are definitely infections that go undetected. Those undetected cases are likely to be the ones that are less severe, so the real case fatality rates usually get lower with more detection. Two, viruses can get milder as they begin to transmit more efficiently among the population. So a bird flu pandemic probably wouldn’t kill a billion people, but that doesn’t mean it wouldn’t be really bad. Dr. Webby: So it’s certainly not going to be 60%.
9:03
I can almost guarantee that, but I do think it would probably be the, you know, probably the worst—the worst flu pandemic that, you know, we have recorded. Dr. Sabeti: Dr. Webby told us that that’s because the virus still has plenty of capacity to cause severe disease. It’s really difficult to try and guess what the actual case fatality rate might be, with some experts putting it at more like 15 to 30%.
9:24
Keep in mind that even a 1% case fatality rate would be a completely awful thing to have happen. COVID-19 hovered around a 1% fatality rate in the United States prior to 2023, and everyone still remembers how horrible that was. The 1918 flu was proportionally deadlier – its case fatality rate was 2.5%. Basically: Even if H5 isn’t as deadly as we think it could be, it’s still the deadliest version of influenza we’ve ever encountered. After the 1997 outbreak, health authorities all
9:53
over Southeast Asia were on high alert for this threat. And in 2003, the alarm bells sounded in Hong Kong once again.
10:03
In late 2002, a mysterious respiratory disease was causing deaths in Guangdong Province, China. Though the Chinese government initially tried to downplay this outbreak, it reached Hong Kong in 2003. H5N1 was known to be circulating in wild birds at the time, and several human cases had cropped up. The natural question experts asked themselves was: Was this the beginning of the long-feared bird flu pandemic? As it turned out, no. This wasn’t bird flu, or a flu at all.
10:28
This was a demon of a different kind: a type of virus thought to be mostly harmless, called a coronavirus. And yet the disease caused by this coronavirus, called SARS, killed in similar ways to flu, by causing a storm in the lungs known as acute respiratory distress syndrome. SARS required similar healthcare responses to severe influenza, like ventilators and hospital beds. And SARS spread in similar ways to flu, though a bit less readily. That means that although it wasn’t flu,
10:55
SARS was a stress test for how we would handle an outbreak of disease similar to flu. So, Dr. Gronvall, how did we do? Dr. Gronvall: We did not learn enough from SARS. We saw that there was this zoonotic spillover from animals to people. That's the way more than three quarters of new diseases—new infectious diseases come about. We never did develop a vaccine. We never did really develop tests for it. What we did learn is that these things can happen and that public
11:26
health can contain it if, if we're lucky. Dr. Sabeti: And we did contain it. The SARS pandemic ended with only about 8500 cases, of which about 11% were fatal. The outbreak was stopped before it could get any worse thanks to old-fashioned, boots-on-the-ground epidemiology. What I mean by that is finding cases, finding who they’ve been in contact with, and isolating them before it’s too late – that’s “contact tracing,” the thing we kept hearing about during COVID.
11:51
SARS proved that it really can work. And yet, hospitals and healthcare workers were overwhelmed in places with the worst outbreaks. So we didn’t exactly pass our stress test with flying colors. While we were earning that C, maybe a B-, the threat of bird flu was growing stronger. As I mentioned, the safecracker that is H5 needs to undergo some very specific changes to be able to infect humans more easily, as well as to spread from person to person.
12:17
But the more opportunities it gets, the more likely that is to happen. And several times in the 2000s, it came terrifyingly close. Once again, we’re going to tell a very sad story here. It’s the tragic case of an 11-year-old Thai girl named Sakuntala Premphasri. Around August of 2004, the chickens in her rural village all sickened and died. Within a few days, Sakuntala herself fell ill. Though she was taken to a hospital for treatment, nobody guessed bird flu.
12:44
Eventually, she was admitted for pneumonia. Pranee Thongchan, her mother, was a garment worker whose job was 200 miles away. When she heard the news, she did what any mother would do and rushed to the girl’s bedside. We can only imagine what she went through as she cradled the girl in her arms for the last hours of her life. Yet things were about to take another turn. As Pranee attempted to return to work, she too fell ill. Not only had she already gone through the very worst thing a
13:07
mother can – the disease would take her life, too. Pranee’s considered one of the first certain cases of human-to-human transmission of H5N1. Her occupation didn’t put her into contact with birds that could make her sick, but she was in very close contact with Sakuntala. Imagine if, in the depths of her grief, as she tried to move on with her life and her job, one of her coworkers had caught the disease from her, and it had spread from there.
13:30
It’s worth noting that Pranee’s sister, Pranom, also got sick, but she was given the antiviral drug Tamiflu and recovered. That brings us back to 2006, to Ponten Ginting, his supernatural dealings, and his children. The eldest daughter Puji was the first to fall ill, possibly through exposure to poultry next to the market stall where she worked. It appears six other family members caught the disease from Puji.
13:53
Only after that does it appear that one of the sons, Dowes, caught the virus from one of them. He developed the symptoms so much later than everyone else that it’s unlikely for him to have gotten it from Puji directly. In other words, this outbreak represented transmission from person to person, and then to another person – something that had not been seen before. Fortunately, it stopped there. A local ritual expert claimed to have protected the remaining family members
14:17
from black magic by creating a protective boundary around them. The only remaining son, Jones, became gravely ill, but recovered. And residents of the community, knowing full well of the patriarch Ponten’s dealing with demons, blamed black magic for the illnesses – not influenza. They refused to take Tamiflu when it was given to them. I want to emphasize that this isn’t foolish behavior – not according to the way these people understand the world.
14:40
In public health, it’s important to try to reach people where they are, not convince them they’re wrong. Otherwise, they may distrust efforts to help even more. We’ll come back to that idea. In both of these outbreaks, we can see two main tools being used. One is contact tracing. The other is oseltamivir, an antiviral drug sold under the brand name Tamiflu. Oseltamivir works by blocking the activity of neuraminidase, one of those other minion genes we talked about.
15:05
It’s given to manage symptoms in patients who are already having bad cases of flu. It can also be used to try to prevent flu symptoms from developing. Now, that all sounds great, and at the time of these outbreaks, it was believed to be one of the best weapons for fighting the influenza virus. However, since then, support for the use of oseltamivir has declined slightly. One mega-review in 2013 suggested that neuraminidase inhibitors like oseltamivir
15:28
don’t do much in terms of preventing symptoms in otherwise healthy people. At least, not enough to be worth the side effects or the virus potentially evolving resistance to the drugs. Yet, these drugs do seem to be great for avoiding death in severe cases and shortening the duration of symptoms, at least when it comes to seasonal flu. And the CDC recommends using oseltamivir for post-exposure prophylaxis in folks who have been exposed to bird flu.
15:49
So we haven’t thrown it out the window, but at the same time, we probably need to concentrate on multiple strategies to make sure we’re ready for the next time the demon strikes. Which it did, in 2009. Dr. Gronvall: The 2009 H1N1 pandemic was pretty unexpected. Everybody had, for years, been preparing for H5N1, and it was going to be coming from Asia, Southeast Asia perhaps, but definitely somewhere not around the United States.
16:19
Dr. Sabeti: The 2009 so-called “swine flu” originated in North America. It was an H1N1 virus, which happens to employ the same two primary minion genes as the devastating 1918 flu pandemic. And while this H1N1 wasn’t the same virus, it had some things in common with it. Three viral lineages, including one descended from the 1918 strain, all infected pigs. They held a sort of genetic white elephant gift exchange, and emerged as a novel virus
16:46
just unfamiliar enough to our immune systems to trigger a new pandemic. You might remember the swine flu as having been “mild.” But the demon is cruel, and mild is relative. Even as the disease spared older people – which is uncommon for flu – it was devastating in pregnant people. Dr. Gronvall: And at the time I was pregnant and just anxiously awaiting the vaccine and eventually was able to get it.
17:11
But I had the fun experience of having my OB tell me, 'cause he knew me as a professional as well as being my doctor, say, "Oh, we lost another healthy woman last week to H1N1." Dr. Sabeti: The 1918 flu was also especially dangerous in those who were pregnant, so perhaps the 2009 version inherited that tendency from the older virus. We might also be able to explain why the 2009 flu spared seniors – which has implications for bird flu.
17:42
There’s a concept in immunology called original antigenic sin. This somewhat poetic name basically just means you never forget your first flu. And depending on how old you are, your first flu might be different than someone else’s. See, after the flu successfully causes a pandemic, it doesn’t just kick its heels up and retire. Rather, it embeds itself in the human population, spreading in seasonal waves around the world. Pandemic flu becomes seasonal flu.
18:07
That means, if you were born between 1918 and 1957, your first flu was H1N1. Between 1957 and 1968, it was H2N2, after 1968 it was H3N2, and of course, H1N1 is now circulating as well – so it can be either one. As soon as the 2009 pandemic broke out, researchers speculated that anyone born prior to 1957 might have some immune protection against H1N1. And while it’s not 100% certain, the idea does seem to be supported by the evidence.
18:37
One group of researchers has applied this concept to bird flu. They were studying two types, H5N1 and another avian flu, H7N9. And they noticed a strange age distribution in which patients got infected with which flu. Specifically, H7N9 is more dangerous in patients who were born before 1968, and H5N1 is more dangerous in those born after. The researchers suggest that for some reason, the H1s circulating prior to 1968 seem to provide some protection from H5.
19:06
That would explain why older folks were less vulnerable to H5. Meanwhile, H3 may promote some protection against H7, hence why younger people were more vulnerable to H5, but less so to H7. This does provide a glimmer of hope. Especially with H1 circulating again, we might not be quite as defenseless against H5 as we thought. Which is good. Because here in the 2020s, the demon is closing in.
19:33
You might recall a very different respiratory disease pandemic that occurred beginning in 2019. In fact, you might be wondering why we’re so worried about flu when the big one hit, and it wasn’t flu at all. Well, it’s because just like with SARS, how we responded to COVID-19 sheds light on how we might respond to the next flu pandemic. Dr. Gronvall: I think we would be more stretched thin during a flu pandemic
19:56
now than we were during covid because there has been less interest in going into public health. At first there was a big surge, and then that has leveled off. I think that there is even more dissonance in the public sphere of how people think about public health. And so I think that it's going to be hard to get expert messages across. So I think it really all depends, I think people, good leadership can really try to turn this around. Consistent public health communication can help,
20:33
but there are negative forces that really make it a lot harder than it needs to be. Dr. Sabeti: We did learn a few important things from COVID-19. We developed testing, and we even turned around vaccines in record time. COVID-19 also showed that we can share data and scientific insights way faster than we could in the past. Rather than waiting to publish formally in a journal, a scientist can upload a paper to a
20:56
preprint server, and another scientist halfway around the world can read it the same day. But… we learned a lot of other stuff, too, about how easily hospitals can run out of beds and ventilators. To put it mildly, we also learned that misinformation can spread quickly, and that it can affect people’s behavior. We learned that people won’t always act purely in the interests of protecting others, nor will they defer to experts just because they’re experts.
21:19
So you might say COVID has helped us a lot in preparing for a flu pandemic. But there’s another side to that coin. Many of us are just tired of thinking about pandemics – and that fatigue causes things to break down, just when they need to be at their strongest. Dr. Gronvall: I think we have some of the elements in place, but I worry that our diagnostic testing is not quite up to where it needs to be.
21:43
We had recommended a lot more interaction between the private sector and government,
21:51
public health, to be able to roll out diagnostic tests more quickly. And I'm not sure that we're there yet. So I think the lesson is that you can't let systems wither and deteriorate so that you can't ramp them up. Dr. Sabeti: We’re tired, and we’re distracted. Unfortunately, us not wanting a pandemic to break out doesn’t mean the demon will politely wait until we’re ready. While we were all distracted by COVID-19, it made its move.
22:20
During the 2010s, it kind of seemed like H5N1 had gone quiet. Nobody talked much about bird flu then. But it was an illusion. Dr. Webby: It didn't cause a lot of outbreaks in poultry and there wasn't a lot of human infections either. But we also got to, when we talk about activity with this virus, we've also got to remember that surveillance, meaning actively going out and looking for this virus, hasn't been constant throughout all this time as well.
22:48
So some of that dip in activity in the 2010s, some of it's probably reduced to a little bit of lack of funding over that time period to go out and actively look for the virus. So a little bit of virus changes over that time, probably a little bit of circulation without us even knowing. Dr. Sabeti: H5N1 was slowly spreading through its native hosts, wild birds. As early as 2005, researchers realized this was going to be a problem. You see, birds are well known for their ability to fly.
23:17
Even though the early outbreaks we’ve talked about were all in Southern or Southeast Asia, H5N1 didn’t stay there for long. It spread to the rest of Asia and North Africa, where it’s been especially troublesome in Egypt. From there it traveled to Europe, and settled in across all of Asia, Africa, and the Middle East. Then, in 2021, something changed. The expert safecracker, H5, evolved a new set of tools that made it even better at getting into bird cells.
23:44
And that allowed bird flu to spread explosively all around the globe. 2.3.4.4b doesn’t sound like a compelling name for a villain. If you were a film producer, you would send that one back to the writers’ room. Yet H5s belonging to the subgroup called clade 2.3.4.4b have taken over the world. It has spread aggressively among wild birds, quickly outcompeting and replacing older H5s. And it’s spread farther than any other H5 avian flu that’s come before.
24:08
It’s now endemic in Europe, meaning it’s embedded in the local population rather than coming through as migrating birds bring it with them. And while it’s not yet endemic in North and South America, at the time we’re making this at the end of 2024, it’s very much here and causing serious problems. Since 2022, this demon virus – with its robotic new name – has been showing up in a troubling number of mammals.
24:32
Among other things, it’s been ravaging populations of seals in South America. It does not seem like it’s worked out how to spread between mammals easily – other than the seals – which is good news for us humans. Rather, these infections seem to be happening because there’s just so much virus around in wild birds. Dr. Webby: When we look at the virus, this current batch of H5s and their ability to infect mammals,
24:55
it doesn't seem to be that much different than other H5s that have come over the past 25 years. So again, my gut feeling is that we're seeing more mammals infected with this virus simply because there are many more infected birds, sick, dying birds that fall out of the sky, and along comes a fox or a skunk or name your scavenging mammal. They take a big old bite of that infected bird and get to have a huge dose of virus and get sick themselves.
25:28
And because the virus was out there in the wild birds, there was plenty of opportunity for domesticated birds to come into contact with them and become sick themselves. In 2022, migrating wild birds in the spring and fall caused outbreaks in domesticated fowl in the United States. These outbreaks required the killing of tens of millions of birds. And this is a real thing we have to think about when we’re fighting back against the demon.
25:50
Bird flu is so deadly in birds that entire flocks have to be culled if infection is detected. That also has real economic costs to people. If you live in the United States, and you’re not a vegan, the virus has probably already affected your life by driving up the price of eggs – an important source of cheap, vegetarian protein. That year also saw the United States’ very first human case of H5N1, in a farm worker involved in carrying out those poultry culls.
26:15
Fortunately, the individual experienced mild symptoms and recovered. That brings us to the present day, and I’m sorry to say, the demon appears to be at our doorstep. More outbreaks among poultry have resulted in more cullings – and more infections in humans. But there’s a weird twist. Cows are getting bird flu. They’re not getting it from chickens, by and large, though they are giving it to chickens. It seems like a single spillover from wild birds
26:40
is now spreading among dairy cattle in the United States. And because there’s not really a system in place for testing and isolating cattle, and because cattle are transported all over the country, it’s spread to multiple herds and multiple states. I won’t quote an exact number because it will definitely change by the time you see this. When we were finalizing the research for this video at the end of 2024,
26:59
there had been at least 58 confirmed or reported cases of bird flu in humans in the US. But again, that number is likely to be higher by the time you’re watching this. You can go to the CDC’s website for up-to-date info. A common infection route seems to be dairy workers getting milk splashed in their eyes. The good news is that – again, knock on wood, and we have a really long production schedule – zero of those people have died so far.
27:23
And yet I told you that H5N1 kills somewhere between 15 and 60 percent of its victims. This gap needs explaining, and no one has an answer for why. The route of infection seems to be one potential reason. The individuals who have been infected by getting splashed in the eyes tend to show symptoms in, well, their eyes. Many have had no symptoms other than conjunctivitis. We do know the H5 safecracker can sometimes break into the cells of the eye, so that’s no big surprise.
27:48
But the fact that it’s not causing much mischief in the lungs is definitely a relief. It’s also possible that just getting splashed with some milk doesn’t give you a large enough amount of the virus to make you really sick. Dr. Webby: Maybe it's infection route. If you're a fox or a bear or a mountain lion and you chomp into a heavily infected bird, you're getting lots of virus in the nose, lots of virus in the mouth.
28:11
Whereas perhaps on those, a milking parlor and a dairy cow herd or a flock of chickens, maybe it's more aerosolized and landing on the conjunctiva in the eye, landing in the very extremities of the nasal passages, maybe it's a dose. Again, if you give a higher dose, maybe you get more severe disease. Dr. Sabeti: The reason we’re seeing mild disease isn’t totally clear. It might seem like the demon has lost its fangs. But scientists can clearly see that’s not the case.
28:44
Dr. Webby: It's something that I wouldn't say exactly keeps me up at night, but it's something I scratch my head about a lot. Why are there all these signals saying this is a really, really, really, really, really, really nasty virus, but at the same time, not causing much disease in the people in the US. Dr. Sabeti: Because outside of the US, cases caused by the same, 2.3.4.4b-derived virus have been severe. One infection was reported in Ecuador and one in Chile, both in 2023.
29:10
While neither were fatal, both caused very serious symptoms. And in case you’re tempted to chalk the difference up to the US’s superior healthcare system, that’s not the difference maker here. The farm workers becoming infected in the US sometimes belong to highly vulnerable groups. They may be undocumented, they may not speak English as a first language, and they may not have great access to healthcare. So it’s definitely not that. But this is where we are right now.
29:32
The demon is all around us. It’s threatening our food supply, and it’s starting to cause infections more and more often. None of those infections have spread from person to person yet – that we know about. But given enough opportunities, it will. And to be clear, the US is not the only place where a pandemic could begin. I know, we really like to make things all about us. A pandemic could start in South America or Southeast Asia or virtually anywhere.
29:54
But this cow situation is bizarre, so it makes sense for all eyes to be on us. The question now becomes: How do we fight back? We have tools to fight a bird flu pandemic. Some are low-tech, like getting boots on the ground to do contact tracing, or to monitor herds of cattle for that matter. Some are more sophisticated, like Tamiflu. And believe it or not, we have vaccines for H5N1. We know enough about how to make a flu vaccine to make one for H5 that we can be
30:19
pretty confident will work – and scientists keep an eye on it in case that changes. A universal flu vaccine is another option. The hunt for something like that is intense and ongoing. It’s so intense that it’s too much to go into, even in a video this long. So in summary: They’re working on it. Other high-tech tools could also come into play. mRNA vaccines, like the ones developed during the COVID-19 pandemic, could certainly have a place.
30:42
But to limit speculation, I’d like to focus on what we could do right now. Supplies of H5N1 vaccine are limited. But it’s hard to see why we shouldn’t use them to protect the people we already know are vulnerable: poultry and dairy workers. Dr. Gronvall: When it comes to how we handle the current H5N1 dairy cow crisis, we have to do things the right way, you have to try to do things to avoid stigma for the people who are at most risk.
31:12
You need to have supportive medical care for those people and explain what the potential risks are. You also can't just put everything on them. And I think they should be offered flu vaccines and H5N1 vaccines when we get them. But we need to be doing much more surveillance of the dairy cows as well. Dr. Sabeti: By the way, the US CDC is offering free seasonal flu vaccines to farm workers in the states most affected.
31:41
Getting vaccinated against seasonal flu probably won’t prevent them from getting bird flu. But it can reduce the burden of seasonal flu in case bird flu cases start to pile up. Unfortunately, getting enough bird flu vaccine in hand could be a challenge. Sometimes, the economic incentives around preparing for a pandemic can be… stubborn. Dr. Webby: We could spend millions to billions of dollars making H5 vaccine now and never, ever, ever have an H5 pandemic.
32:08
So it's tough, but at the same time, the potential consequences of an H5 pandemic are terrible. So there are going to be resources well spent either way, in my mind anyway. Dr. Sabeti: Whether with vaccines or something else, we have a responsibility to protect these farm workers. And what’s more, it needs to be now, not when it seems like a pandemic is already breaking out. Dr. Gronvall: I think now is the time where we should be concentrating on providing
32:34
those resources, any medical resources to the people who are most at risk for being infected. We shouldn't be thinking about waiting until there's an actual epidemic forming. We should be concentrating on making sure that the people who are at most risk are most protected. And that includes the people and the animals that are closest to the dairy cows that are infected. Dr. Sabeti: As Dr. Gronvall told us more than once,
33:03
we can’t make it the responsibility of the vulnerable to prevent a pandemic. We learned from the Gintings, as well as from countless people during COVID-19, that people will act in a way they believe to be their own interests. Good science communication and good public health leadership will be crucial. Because as I mentioned, many of the people in the most danger in the US are undocumented, or not in a great position to trust the healthcare system.
33:25
Building trust in public health is hard. Sometimes, it’s about convincing someone who sincerely believes a malevolent spirit caused their illness that Tamiflu is the best way to protect their community. Sometimes, it’s about explaining the need to wear eye protection when milking, even though people aren’t getting all that sick. It isn’t easy, and people will be mistrustful and defensive sometimes, because they’re people. Dr. Gronvall: And so you have to put structures in place,
33:49
you have to have leaders who talk about this. You have to make things available, and you have to communicate effectively. And this has been done with variable degrees of success over the last decades. Dr. Sabeti: So vaccines, plus monitoring, plus good leadership. Sounds like a recipe for success. Does that mean we’re ready for a bird flu pandemic? Dr. Gronvall: We are not ready for a bird flu pandemic. Can we get ready? Absolutely. We're making things a little hard for ourselves. We...
34:23
I don't know if this is containable anymore, given the number of herds that are infected. If it turns out that this is nothing, great! But this is a great opportunity for us to get better at figuring out how we can stop something like this and we should take advantage of that at minimum, to be able to stop the chains of infection to figure out what's causing it and to protect the people who are most at risk.
34:51
Dr. Sabeti: We have to act now because, unfortunately, we can’t see the future. Dr. Webby: I think if we look at that from the current situation we're in, let's think about this virus running through our dairy industry. Are we prepared for that? Have we been prepared for that? No, not at all. One, from an ability to respond. Two, from having plans in place as to what happens if this virus gets into dairy cows. There is no plans for that because one, this virus doesn't get into dairy cows.
35:24
So why would you even have a plan for that? And of course it did, so we needed it. Dr. Sabeti: Apparently, we still have some work to do. Fortunately, so does the demon. Despite how close it is, it still needs to figure out human transmission. It’s had so many opportunities, but so far, it’s failed every single time. We know, at a molecular level, exactly what would have to change… and it hasn’t. Dr. Webby: We are look at its ability to grow in different cells and in different hosts.
35:49
It's still very much an avian virus. So from that perspective, it does have to change quite a bit before it could become human to human transmissible. And the fact that it hasn't done so over the past 25 years, despite having lots and lots of opportunities to do so, at least to me suggests the barrier for this virus to switch from being a bird virus to being a mammal virus, a human virus at least, is probably quite high. Dr. Sabeti: A bird flu pandemic could happen tomorrow.
36:20
Or it could never happen. So why did we say a pandemic is almost inevitable? Well, no one can know that, of course. But it’s a matter of opportunity. Nothing guarantees that H5N1 will evolve human-to-human transmission. But its increased presence in wild birds, poultry, cows, and humans is giving it the chance to take as many shots as it likes. Dr. Webby: The hardest question to answer is what is the actual risk of this virus.
36:44
I can talk in terms of relative risk. So I think in terms of relative risk, we're probably as high as we've ever been with H5 virus, just simply because way, way more exposure of humans to infected animals. Dr. Sabeti: Relative risk is still relative, and in absolute terms the risk is probably still low. But the problem is that we currently have the perfect conditions for it to happen. Dr. Gronvall: Is H5N1 and these sporadic infections and this ongoing
37:15
problem with dairy cows, is this going to be the next pandemic? No one can say. What we can say is that there is no other logical path that we know of for how you get to a pandemic than having these infections occur in animals and spill over to people. Dr. Sabeti: We are going to have a lot of choices ahead when it comes to meeting the challenge this influenza virus poses. Some of it is about science and technology – making sophisticated new tools to protect ourselves.
37:44
Some of it is about leadership and public health – meeting people where they are with the information they need to make good decisions. And some of it is about basic empathy – making sure the people in the most danger are protected, no matter who they are. How we meet the demon in battle will say a lot about ourselves. And just like with SARS, COVID-19, or past influenzas, what we learn will apply to every flu we have to fight in the future.
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But with science on our side, I’m hopeful it’s a fight we’ll win.
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[♪ OUTRO]
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