[narrator] Let's imagine, for a second, all the ways the world could end.
It could be something from above.
Or something from below.
Or it could be something we did to ourselves.
But there's one thing that consistently ranks
as one of the most likely things to end the world...
Well, if you think of anything that could come along
that would kill millions of people,
the pandemic is our greatest risk.
[narrator] A pandemic is a disease that escapes our control,
sweeping across the world,
killing millions and changing civilizations.
We know this because we've seen it before...
a few times.
In the 6th century, a pandemic killed half the world's population.
In the 14th, another wiped out half of Europe.
And in the 20th, a pandemic killed
almost five percent of the world's population in just two years.
But that was a hundred years ago.
We've learned from these past pandemics and made incredible advances.
Improved response, improved training, improved workforce...
We have improved surveillance systems, improve communications.
We have organizations like the World Health Organization, CDC...
We have improved diagnostics, improved drugs, therapeutics, vaccines.
[narrator] And yet the risk of it happening again has never been higher.
[man] We've done the math on this.
We estimate there are about five new emerging diseases happening
somewhere on the planet every year,
and that rate is accelerating.
So it is inevitable that they will become pandemics.
Mother Nature is the ultimate bioterrorist.
[narrator] We're in a race, and the stakes couldn't be higher.
This simulation estimates that a pandemic today could kill 33 million people
in just six months.
In terms of a death toll, a pandemic would rival even the gigantic wars of the past.
The economy will shut down.
The cost to humanity will be unbelievable, and no country will be immune
from the problem this will create.
[narrator] So the question is not, is the next pandemic coming...?
There are only three things that are inevitable in this world.
Death, taxes, and flu pandemics.
[narrator] Or... when is the next pandemic coming?
We estimate there are around one and a half million viruses in wildlife
that we don't yet know about.
Any one of those could be spilling over into the human population right now.
[narrator] The question is...
will we be ready for it?
Influenza pandemics must be taken seriously.
The world is fighting the worst Ebola epidemic in history.
The stakes couldn't be any higher.
[man] A virus can be just as destructive as a bomb or a missile.
[man 2] Pathogenic organisms recognize no boundaries lines.
[woman] Residents believe their town is ground zero for the swine flu epidemic.
[man 3] All sorts of animals may be the culprits.
[man 4] A sick person can be healed,
but in the meantime, he spreads the disease.
[man 5] The campaign against infectious disease can succeed
only if the public cooperates.
[man 6] We just don't know what the future is going to hold.
[narrator] Pandemics begin in a world invisible to the naked eye.
Microbes were likely the first living things on earth.
Many can't replicate on their own,
so they hijack other living cells.
And today they're all around us.
And on us.
And in us.
Many arrive in peace, but others damage or kill our body's cells.
Fever, coughing, sneezing, diarrhea... that's our body fighting back.
But some are so strong, they can overwhelm our immune system...
and kill us.
Pandemics are mainly caused by two types of microbes:
bacteria and viruses.
The interesting thing about viruses is they are supremely adapted to jump
from one species to another.
They're the most likely microbes to become the next pandemic.
[narrator] As you can probably guess, viruses that cause bird flu
come from birds.
Swine flu comes from pigs.
HIV came from chimpanzees.
Ebola likely comes from bats.
And several diseases come from mosquitoes.
When these spill over to humans, the new virus is called a zoonotic virus
and they're extremely dangerous.
These are viruses which mutate rapidly and therefore change the surface
and evade immune responses quickly.
They can transform into a new virus once they get into the human population.
Now those don't happen all the time.
They're quite rare events.
[narrator] But when they do, the effects can be devastating...
which brings us to a farm in Kansas a century ago.
Experts aren't certain, but they believe the 1918 flu pandemic could have started
when an infected bird and an infected human
met the same pig.
The bird had bird flu, a type of influenza virus that have been
infecting chickens, geese and ducks for at least a hundred years.
While the person had a different influenza strain, the seasonal flu
that had made humans feel stuffed up and feverish for centuries.
The two viruses couldn't infect each other's species,
but they could both infect pigs.
And in one pig cell, those two viruses combined,
creating a new zoonotic virus: H1N1.
These parts from the human virus gave it the ability to infect humans,
but these parts from the bird virus prevented immune systems
from recognizing it and effectively fighting back.
A deadly combination.
It killed somewhere between 50 and 100 million people around the world.
It was unlike anything else in history.
[narrator] You can think of a disease on two scales:
how contagious it is and how deadly it is.
Here is the seasonal human flu
while this is the bird flu.
And this is the 1918 combination.
It was so contagious because it was airborne,
meaning the virus could hang in the air, infecting anyone who inhaled it.
And a 1918, it infected one in every three people on Earth.
Then it killed almost 5% of the world's population.
The final ingredient was human technology.
This flu emerged in the middle of the first World War.
We were sending people across from the U.S. into Europe for war
and then we were bringing them back.
So this virus exploited those travel patterns
and spread around the world very quickly and very effectively.
[narrator] In fact, in every past pandemic,
human technology is responsible for taking diseases around the world.
The Black Death arrived in Europe on ships in the 14th century.
It was two distinct diseases:
Bubonic plague, which killed as many as 60% of the people who got it.
And pneumonic plague, which killed almost everyone who got it.
Then there was smallpox.
It was less deadly than the Black Death,
killing 30% of the people who got it, but it was more contagious.
Humans spread it around the world.
In the 20th century alone, it killed around 400 million people.
These other diseases have also become pandemics.
But eventually, we developed technology that could defend us.
The practice of isolating travelers for a time to see if they were infected,
now known as quarantine,
was first developed during the Black Death.
Then we invented microscopes,
allowing us to see the enemy for the first time.
Next, we developed antibiotics.
These made these diseases spread by bacteria far less deadly.
And smallpox led to the development of the first ever vaccine
which defends us against some viruses.
The way a vaccine works is we get injected with proteins from the virus
and we create our own antibodies.
These are little molecules that attach to those proteins and neutralize the virus
and allow it to be swept out of the body.
So when we get infected by a real virus, we can rapidly create an immune response,
send out these antibodies, and get rid of the virus.
[narrator] If enough people in a population get vaccinated,
it's almost impossible for the disease to spread.
So smallpox was declared eradicated in 1980.
And these diseases don't cause nearly the amount of deaths they used to.
And antiretroviral drugs have made viruses like HIV far less deadly and contagious.
Finally, the internet is helping us detect and contain diseases earlier.
This is why studies show that fewer people are contracting infectious diseases today.
But at the same time, the number of outbreaks is increasing,
and that is largely because of emerging zoonotic viruses.
Out of an estimated 1.6 million unknown viruses in wildlife,
we currently know of about 3000.
So it's really less than 0.1%.
[narrator] That means the next pandemic
could be a virus that we're not prepared for.
[Daszak] We know some pretty lethal ones,
but we expect that there are others out there that are more lethal,
that are better at being transmitted,
where we've got no drugs and no vaccines. They're the big risk.
[narrator] This is called Disease X.
And we know we're unprepared because we've seen them before.
[indistinct chatter]
This is a wet market in the Lianghua, China.
Unlike markets in much of the West where animals are already dead when they arrive,
this wet market sells meat that's very fresh.
It's killed on sight.
That's what makes it a Disease X factory.
Many different animal species are stacked on top of each other,
their blood and meat mixed, before being passed from human to human.
All the while, their viruses are mixing and mutating,
increasing the odds that one finds its way into humans...
which is likely what happened at a market here in southern China in 2002.
Back then, some wet markets in China sold wild animals
like snakes, civet cats, and bats.
And demand for them was high.
On November 16th, a man in Foshan, China got sick
after preparing a meal of chicken, cat, and snake.
He had the symptoms of pneumonia.
Fever, cough, and trouble breathing.
When treatments for pneumonia didn't work,
Chinese officials reported it simply as "atypical pneumonia."
But then it started spreading.
And people started dying.
There were reports of clusters of respiratory infections
in hospitals in China.
[man] But we're used to that. There were strains of influenza virus
that caused flu in Asia many times over.
Um... and we always noted them and there was always concern,
but they were not particularly scary to us.
But people like the CDC and the World Health Organization
start to take notice of these rumors of illness
and went to the Chinese government and asked, "What is going on?"
And the way that the world found out about it is that someone
from one of those towns decided to go to Hong Kong.
[McKenna] Hong Kong was a uniquely bad place for this to happen.
[narrator] In 2003, Hong Kong was home to about seven million people.
Over 16 million tourists visited each year,
and over 500 international flights took off and landed there every day.
On February 21st, one man arrived.
He was already feeling sick.
He checked into the Metropole hotel
and headed up to his room on the 9th floor.
There, he threw up or coughed,
spewing droplets all over the elevator and hallway.
That's how he infected 16 people
who would spread the disease around the world.
The man in this room boarded a flight the following day,
arrived in Hanoi, Vietnam, and checked himself into the hospital,
where he infected doctors and nurses.
One of those doctors then took the disease to Bangkok.
That's when the World Health Organization declared an international emergency
and officially named the disease.
Severe acute respiratory syndrome.
Or SARS for short.
[narrator] A few days later, scientists found the cause:
a virus they had never seen before.
Back at the Metropole, a woman in this room
flew home to Toronto and died.
Her son checked himself into the hospital.
I remember sitting there, my kids were there,
and I was watching the news and all of a sudden I saw
a picture of my hospital, Mount Sinai Hospital, on the news.
That was the first time it hit home that this was going to be a problem.
It was about a week later when we identified
that there were a substantial number of staff at the hospital
who were also ill with SARS.
Who's going to be on call on Tuesday? We have to get somebody else.
What was their job? Who's going to fill in for them?
Sometimes just losing one senior resident in our department
throws the whole department into chaos.
I was feeling fine when I got home,
but I woke up in the middle of the night not feeling well with a fever and...
then I knew that was probably what I had.
[narrator] By late March, 47 hospital staff were sick in Toronto
and hundreds more were in quarantine,
including Allison.
This was one of the scariest things about SARS.
It's early symptoms were subtle and hard to identify,
causing outbreaks even in advanced hospitals.
Back in Hong Kong, a nightmare was taking place.
SARS was spreading faster than ever.
A man with SARS was in this unit of an apartment complex.
He had diarrhea and when he used his toilet,
the SARS virus was carried through the pipes to the unit below
where a fan blew the virus back up into the building's ventilation
and into the apartments above.
Then the wind was likely blowing the virus to nearby buildings,
making it much more difficult to contain.
[man] That's truly a nightmare scenario.
You're not physically in contact with a known infected person.
So it's much harder to track because we don't necessarily know
the source of the contamination or the infection.
[narrator] In total, 329 people were infected in this apartment complex
and hundreds were quarantined.
By now the world was panicking.
[woman] The fear that dogs and cats can carry SARS
has led some residents in Beijing to abandon their cherished animals.
[woman 2] Taxi authorities have set up points
to test cab drivers for high temperatures,
one of the symptoms of SARS.
In part, it's all down to how much we, the public,
trust what we're told by officials.
Is it absolutely out of the question that this could have been something
inflicted upon people by a terrorist agent of some sort?
I think in March of the year 2003, we exclude nothing.
[narrator] 1755 people were infected in Hong Kong and 300 died.
In Toronto, 251 were infected and 41 died.
With cases in at least 26 other countries...
ultimately, SARS killed 774 people, about 10% of those it infected.
But then SARS did something totally unexpected...
The funny thing about SARS is that after a while it just kind of goes away.
SARS just wasn't that hardy a virus.
We didn't know that when it started, but that's how it turned out.
But I don't think that's a success story.
I think a lot of that is just luck.
[narrator] Because a lot of mistakes were made.
Chinese health officials only admitted there was an outbreak
after 18 people had already died, and hundreds of others were sick.
[in Mandarin] We will try all means to reverse and improve upon the weaknesses
and faulty aspects of our work.
[narrator] After the SARS epidemic, the World Health Organization
brought together 196 countries, and they all committed to improving
their ability to "detect, assess, notify, and report public health events,"
including outbreaks.
In 2014, only a third of them were in compliance.
The big problem with the pandemic is we don't know when it will come.
And so it's very easy to put off to another day.
It really takes an extraordinary act of political will to say,
"Yes, right now things don't look that bad,
but we're going to send funding to public health anyway
because we know that someday it will be bad."
[narrator] SARS showed how far and fast a virus can travel in our modern world.
SARS went around the world in weeks.
It's entirely possible that the next will go around the world in days.
That's far faster than we could ever catch up.
[narrator] Which means, if we want to stop the next pandemic,
our best bet is catching it at the source.
SARS began as a virus living silently in a wild animal.
Experts believe it was bats here in southern China.
These scientists have been coming to these caves since the outbreak,
catching bats and scanning them for viruses similar to SARS.
And they're finding a lot,
which is allowing them to create an early warning system.
And when we find them we raise the alert, and the government of China comes in
and tries to reduce the exposure of those populations to viruses.
[narrator] China is not the only place these viruses are being found.
This map shows where a new virus is most likely to emerge.
The front line for disease emergence are places like the end of the road
in a tropical forest where someone's just built
a new mining concession. People have moved in.
There's no food supplies so they go out and hunt wildlife.
Or it's a farm in Southeast Asia that's been expanding and intensifying
that has bats nearby that spread viruses into the pigs in the farm.
This is a revolutionary way to defend ourselves against future pandemics,
but it won't catch every new disease.
For that, we need to improve our vaccines.
If a disease comes along that we haven't seen before,
typically it would take four or five years
to come up with a vaccine against that disease.
And new technologies might shorten those times.
[narrator] That's why an organization called CEPI was founded.
And they're developing a vaccine for Disease X.
Traditional vaccines inject protein molecules from a virus,
and manufacturing these proteins is a long and expensive process.
But this new vaccine doesn't use proteins.
It injects genetic material that tells the body to produce those proteins itself.
Your body becomes the manufacturer, creating the protein molecules
and then the antibodies for them.
Scientists can customize the genetic material to get the body
to produce the protein molecules of almost any virus.
Once they figure out how to deliver this into the body,
it could reduce the time it takes to develop a new vaccine
from several years... to just 16 weeks.
Meanwhile, scientists are trying to develop a universal influenza vaccine,
one shot that could immunize us from every possible flu strain for life.
None of those universal flu vaccines, as they're called,
are anywhere near to being deployed in the population yet,
but the U.S. federal government and governments in Europe
have been supporting that research in a way that they didn't
a couple of decades before, because they understand
that flu really is an eternal and very serious threat.
[narrator] The truth is human technology has made the next pandemic inevitable.
Deforestation is bringing
more wild animals into contact with more people.
And factory farming is pushing animals closer together,
giving their viruses more opportunities to combine into one that could infect us.
Then we give them more ways than ever to spread.
But human technology has stopped pandemics before,
and it's our only chance against the next one.
We know that, because we've been in this race since life on Earth began.
When a pandemic comes along, of any size,
we always look back and wish we'd invested more.
We are far short of what needs to be done.
[theme song playing]