How COVID-19 human challenge trials work -- and why I volunteered

In April 2020, epidemiologist-in-training Sophie Rose volunteered to be infected with the virus that causes COVID-19. As a young, healthy adult, she's offering to take part in a human challenge trial, a study where participants are intentionally exposed to SARS-CoV-2 to test vaccines and gather critical data. Explaining how challenge trials could speed up the development of effective vaccines, Rose shares why volunteering was the right decision for her.

[Recorded on October 26, 2020.

COVID-19 vaccine development

and ethical considerations
around human challenge trials

are constantly evolving.]

In April 2020,

I made what many perceive
as a risky decision.

I volunteered to be deliberately
infected with COVID-19.

This infection would be part
of what is called a human challenge trial,

where young, healthy people
are given a vaccine

and are deliberately exposed
to the virus that causes COVID-19.

These trials help researchers
figure out more quickly

if a vaccine is working.

I think this research is crucial,

because today, I'm going
to speak to you for six minutes.

In that time,

roughly 1,250 people will be
confirmed infected with COVID-19.

Twenty-one people will die.

And then this pattern will repeat
hour after hour and day by day,

until we're able to vaccinate
most of the eight billion people

affected by this global crisis.

Scientists have been working
around the clock

to make those vaccines a reality.

But what should we do when the human cost
of waiting for those vaccines

is rising by the day?

This is where human
challenge trials come in.

They're different from the traditional
phase three vaccine trials

taking place now,

where people are given
a vaccine or placebo

and asked to go about
their everyday lives.

Here, researchers have to wait
to see how many people in each group

become infected.

Until enough of them get sick,

we don't have enough data
to know whether a vaccine is working.

Finding an effective vaccine
with this method

can take months or sometimes years,

and it requires thousands of volunteers.

A challenge trial works faster

because researchers control exposure,

instead of waiting for people to get sick.

So instead of a year,

we could know in as little as a month

whether a vaccine seems effective.

Instead of thousands of volunteers,

a challenge trial relies
on just 50 to 100.

Because we know for certain

when people are exposed
and develop disease,

these trials also allow us to gather data

about the early stages of infection
and our immune response.

This data is impossible to gather
in any other way,

especially for people who become infected
but never show symptoms.

This knowledge is important
for designing policies

that limit COVID-19 transmission.

The time saved translates
into precious months' head start

on manufacturing,

getting us more working
COVID-19 vaccines faster.

These trials are useful --

even though recent phase three results
sound encouraging.

The arrival of the first vaccine
is going to be a monumental breakthrough.

It just isn't quite the fairytale ending
we're all hoping for.

We're going to need multiple vaccines,

because we just don't have
the infrastructure needed

to immunize all eight billion people
on the planet with just one kind.

Each type of vaccine requires
its own special process and equipment

to make, store and deliver it.

If we had multiple
working COVID-19 vaccines,

we could make use of all
of our equipment at the same time.

Some of the leading candidates
need to be kept extremely cold

before they are delivered to people.

This can be really hard,

especially in countries
where there isn't reliable electricity

or a secure method to store them.

Scientists have been using
human challenge trials

for hundreds of years.

They've sped up the development
of vaccines against typhoid and cholera,

and they've helped us better understand
how immunity develops

to things like the flu,
malaria and dengue.

We've even used them
for other types of coronavirus before.

There's been a lot of debate

about whether challenge
trials are too risky.

I happen to think
that those risks are worth taking.

A challenge trial would only recruit
young and healthy participants --

think between the ages of 20 and 29.

Fewer than one percent of people
in that age-group

need to be taken to hospital
after becoming infected with COVID-19.

So it would likely be even lower
in a challenge trial,

because researchers check to make sure

that participants have
no preexisting conditions.

The risk of a young healthy person
dying of COVID-19

is around five thousandths of a percent.

That means for every 100,000 20-year-olds
who become infected with COVID-19,

about five die.

If I were to give birth
in the United States,

my risk of dying
would be higher than that.

Or you could choose
to think about it this way.

If my little sister needed a kidney,

I wouldn't hesitate for a moment
before I offered her mine.

And if I can take on that risk
to benefit a loved one,

it makes sense to allow people
to take on a similar risk

to speed up the development of a vaccine

that would benefit
not just their loved ones,

but everyone around them as well.

There's a lot we still don't know,

especially about the long-term
effects of COVID-19 infection.

I volunteered despite that uncertainty

because like many of you,
I feel frustrated

knowing that hundreds
of thousands of people are dying.

And that's without mentioning
the millions more who are struggling

as measures to stop the spread
take a toll on their physical,

emotional and mental well-being.

It turns out I'm not alone
in feeling this way.

Since May, over 39,000 people
from across the world

have volunteered to participate
in potential COVID-19 challenge trials

through a nonprofit I helped found
called 1Day Sooner.

We advocate for challenge
trial participants

and have been encouraging stakeholders
to begin preparing for these trials.

As early as May,

when challenge trials
were still being considered

for their role in the fight
against COVID-19,

the World Health Organization
cited 1Day Sooner

as an example of the kind
of public engagement needed

to run a challenge trial.

In mid-October,

the UK government
formally announced their intention

to conduct a challenge trial
at the beginning of 2021.

It is clear that the COVID-19 pandemic
is a global crisis.

It has inspired
record-shattering innovation,

and it has highlighted the heroic acts
of many frontline workers,

but is has also taken a catastrophic toll.

The arrival of each new vaccine
brings us one step closer to rebuilding.

But the true global solution

lies in those vaccines being in the hands
of people all over the world.

Challenge trials could be
a part of that solution.

Thank you.