How do we develop a new vaccine?

After lots of laboratory work, how do we
know it is ready to get tested in humans?

And then, how do we know 
whether or not it works?

We test new vaccines in clinical trials to
determine that they're both safe and effective

before they get licensed in the US.

Stick with us, this is going to be interesting.

And, although this applies
to all kinds of drugs and vaccines,

we're going to focus here on vaccines used for
prevention of a specific type of infection.

The first thing to know is that a lot of
testing is done before a vaccine

ever gets tested in humans.

There is a long process of development in
a laboratory,

and testing, both for safety and for 
protection, in animal studies.

After we have a vaccine that looks both safe
and promising in preventing infection

in a laboratory, we begin testing in humans.

Because we don't know whether or not
the vaccine will work,

we begin a very structured set of studies
called clinical trials.

These studies involve healthy volunteers,
who are told in detail about how and why

this vaccine is being tested, and about any
potential harm.

This educational process is a process
called informed consent,

and goes on before and during the trial.

There's a continual discussion that happens
between the researchers

and the study volunteers.

Describing the study, informing the
volunteers about any new information

that happens at any time during the study,

and answering all questions that
the volunteers have.

The study staff also determine whether
the volunteer meets all the eligibility

criteria to participate, which involves
physical exams and blood tests.

Next, we start what is called a ramdomized,
double-blinded clinical trial.

What that means is that after volunteers
enrol in a study,

a computer randomly decides whether they
will get the vaccine

or whether they will get the placebo,

which is usually just salt water.

We do this to be able to separate outside
effects that are due to the vaccine

from those that are just happening to
people in a community at the same time,

like the rate of cold symptoms,
or headaches.

And, we double-blind, meaning neither
the participant nor the study staff

know who is getting which type of injection.

That prevents both the volunteers and the
staff from over or under reporting symptoms.

We advise participants to tell us about
everything that is happening to them.

Before a vaccine is licensed by the
US food and drug administration,

it usually goes through 3 phases of
clinical trials,

each of which has a specific purpose.

Phase 1 trials, which can last up to 2 years,

compare the safety - does the vaccine
cause any side effects,

and tolerability - does the injection hurt,
and for how long?

In this phase of studies, scientists are
also gathering information about

the body's immune response to the vaccine,

to see whether it is a promising approach
to preventing this specific infection.

Phase 1 trials do not determine whether
or not the study product is actually doing

what we hope it will do.

Phase 2 trials, which can last
longer than 2 years,

will confirm the safety in a larger group
of volunteers,

and focus on the best dose and the best
timing of vaccinations to produce

the strongest immune response.

Promising vaccines that are safe and
generate a strong immune response

move into phase 3 trials.

These are the largest trials, and compare
the rate of infection in the vaccine and

placebo groups.

This will tell us whether the vaccine is
able to prevent infection,

and, if so, if it is effective in all of
the volunteers, or only a sub-group,

like younger volunteers, or women.

Along with the safety data that is collected
in all phases of vaccine studies,

this efficacy data is used by the FDA to
decide if the vaccine should be licensed,

and, if so, for whom it is recommended.

In the best case scenario, it could take
6-10 years for a promising vaccine to move

from phase 1 testing
to real world distribution.

Often it takes longer.

The clinical trials are absolutely 
necessary to determine that a vaccine

is safe and effective in preventing 
new infections.

This video has been provided to you by
Youreka science, in collaboration with

BridgeHIV.

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