This is a chart of Covid-19 cases in the UK.
In April, the UK’s rate of new cases climbed
so high that it was second only to the US.
Around that time, researchers at Oxford University
who were developing a Covid-19 vaccine
had started planning to do a large-scale test
of the vaccine in the UK.
But by July, new Covid-19 cases in the country
had fallen.
It was good news -- but it also meant the
UK was no longer a good place to test a vaccine.
And that’s because of a crucial part of
the process of testing any new vaccine:
What’s called the Phase III human trials.
Before we can end the coronavirus pandemic,
a vaccine developer will have to give tens
of thousands of participants either the vaccine
or a placebo.
And then... we wait, for months,
or possibly years,
to see how many of each group
eventually gets Covid-19,
while the participants go about
their lives; which, right now,
probably means they are living
under Covid-19 restrictions,
like wearing masks and staying at home.
But until enough of those participants get
sick, there won’t be enough data
on whether the vaccine is working.
And in the meantime, thousands of people are
dying of covid-19 every day.
That’s why, some people are starting to
advocate a different, more controversial model:
Instead of waiting for the coronavirus to
eventually infect some of these people....
What if we gave a group of willing volunteers
the virus on purpose?
“I’m a young guy, I'm 23 years old, I’m
relatively healthy.”
“I have no pre-existing health conditions.
I have no children, no dependents.”
“It’s really important that we do everything
we can to speed up research and development.”
It’s 2016, and this man is about to drink
a test tube of the bacteria that causes typhoid.
He’s one of about 100 participants who deliberately
infected themselves with it
to test a new vaccine in the UK.
“In March 2016 I downed a shot of typhoid.”
Daina was another participant.
She was a PhD student, who needed the money,
but she also liked the idea of it.
“It was like, you know, I'm helping to make
this disease less deadly.”
This kind of study is called a human challenge
trial.
And in the case of the typhoid vaccine, researchers
told the New York Times
that doing the challenge trial
saved them three or four years.
To put that in context, it helps to look at the bigger
picture of how a vaccine normally gets developed.
The first step in the process is to test a vaccine
in a lab on either human cells, or on animals,
just to see if it causes any harm.
This is called the preclinical phase.
If it passes that test, it enters human trials.
This is the longest and most important part.
If it passes human trials, the vaccine gets
licensed by regulators,
and can be manufactured
and distributed to the public.
Human trials typically have 3 phases, each
one testing a larger and larger group of people.
Phase 1 involves a very small group of people,
maybe 50, and mainly tests if the vaccine is safe.
Phase 2 usually involves a few hundred participants.
This is where we start learning if the vaccine
actually works.
And then there’s the final test: the Phase
3 trial.
It’s expensive, it takes time, it requires
tens of thousands of volunteers, and it involves
as broad a cross-section of participants as
possible.
The entire process of developing a vaccine
usually takes around ten years.
But many Covid-19 vaccine developers are racing
to compress this entire process into about
a year and a half.
One way they’re doing this is to overlap
the different phases,
conducting several different trials at once.
Or, to ramp up the manufacturing of a vaccine
while it’s still being tested, so that if
it works, it can be distributed right away.
As of the making of this video,
there were 166 Covid-19 vaccines
in various stages of development.
24 vaccine candidates are already in the human
trial phase.
And 5 of them are already in Phase III.
For these leading candidates, a human challenge
trial could save weeks, or months,
by augmenting a Phase III trial
that isn't getting data fast enough.
And for any of these candidates in pre-clinical phases,
a challenge study, followed by
a larger-scale safety study for the vaccine,
could replace a Phase III
trial altogether.
A challenge trial that successfully shrinks
down this timeline could save thousands of lives.
And so far, a grassroots movement has recruited
more than 30,000 volunteers, from over 100 countries,
who said they would participate
in a challenge trial for covid-19 if it happens.
“My moral values say that I kind of have
an obligation to do what I can to help.”
“I see it as very similar to other acts
of public service, like trying to fight climate change,
and disastrous events that are forthcoming
that are the consequences of a lack of care.”
“It’s affecting, literally, pretty much
every person globally.
I feel like I need to do something to help.”
Here’s the problem.
Human challenge studies have been used before
for cholera, typhoid, malaria, influenza and
the common cold.
But there’s a big, important difference that sets
covid-19 apart.
“For each of those conditions, we do have
effective treatments so that we know,
to my knowledge, no one has ever actually ever died
in those studies.”
Peter Smith is one of the world’s leading
epidemiologists, and he was one of the first
to advocate for the possibility of human challenge
trials, in March of this year.
He says, because there’s no covid-19 treatment,
it limits who could participate in a challenge study.
“The challenge trial would necessarily be
done in people
who were at very low risk of serious disease."
In other words, unlike in a typical Phase III trial,
where you’d recruit the widest range of people possible,
a Covid-19 challenge trial would produce data
on a much narrower group of young, healthy people.
And we don’t know if a vaccine that works
for that group would work for everyone.
But the immediate goal is not to get a single
Covid-19 vaccine that offers perfect protection.
In the US, to be deemed sufficiently effective,
a vaccine just has to work 50% better than
not being vaccinated.
An imperfect vaccine could still slow the
spread of the virus.
The bigger issue with a covid-19 challenge
study
is that there’s no way to guarantee
that it's actually safe for participants.
On one hand, the risk of hospitalization for
young people is relatively low.
And a study of the outbreak in New York City
suggests the risk of death for young people
is as low as 0.01 percent.
And advocates for Covid-19 challenge trials
say that’s a level of risk we already accept
in similar situations.
They point out it’s even lower than the
risk of fatality from donating a kidney.
But any risk of harm or death at all would
still set it way apart from any other challenge study.
And the long-term risks of Covid-19 for those
who recover are still almost entirely unknown.
We emailed nearly all of the institutions
who were reachable who are currently developing
a vaccine, to see whether they would consider
human challenge trials.
And none would go on the record saying they
are considering it.
But we know at least one is seriously considering
it.
Developers of the Oxford University vaccine
said that they hope to do challenge trials
by the end of the year.
In 2016, the World Health Organization’s
stance on challenge studies was that
"it would not be ethical or safe” to use them for
a disease that is “virulent,” and has
no “existing therapies” to treat it.
But in May of this year, they released new
guidelines, saying that they could theoretically
be considered if there was confidence that
“the potential benefits of SARS-CoV-2 challenge studies
outweigh the risks.”
If challenge studies do reduce the time it
takes to get a vaccine, those benefits are clear.
If the current leading candidates have quick,
successful Phase III trials, we may never
need to do a challenge trial for Covid-19
at all.
But if we do, it’ll only be possible because
there are people out there willing to take on this risk.
“It’s worth it to me to save the lives
of a countless number of people.
“I'm happy to take that small risk to myself…
and make things better for a lot of people.”
“Feeling like I was doing nothing, and
just feeling miserable and demoralized,
to being like, OK, I have something I can do here.”
“I'm a lot less at risk than my parents
and grandparents are,
And my moral imperative tells me I have to do it.”
