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How do we develop a new vaccine?

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

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

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

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before they get licensed in the US.

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Stick with us, this is going to be interesting.

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

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

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

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ever gets tested in humans.

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There is a long process of development in
a laboratory,

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

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

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in a laboratory, we begin testing in humans.

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

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

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

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

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This educational process is a process
called informed consent,

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and goes on before and during the trial.

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There's a continual discussion that happens
between the researchers

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and the study volunteers.

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Describing the study, informing the
volunteers about any new information

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that happens at any time during the study,

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and answering all questions that
the volunteers have.

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

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

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

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

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a computer randomly decides whether they
will get the vaccine

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or whether they will get the placebo,

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which is usually just salt water.

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

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

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like the rate of cold symptoms,
or headaches.

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

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know who is getting which type of injection.

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

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

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

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it usually goes through 3 phases of
clinical trials,

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each of which has a specific purpose.

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

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

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

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

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the body's immune response to the vaccine,

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

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

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what we hope it will do.

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

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will confirm the safety in a larger group
of volunteers,

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

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the strongest immune response.

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Promising vaccines that are safe and
generate a strong immune response

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move into phase 3 trials.

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

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placebo groups.

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

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

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like younger volunteers, or women.

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

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

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and, if so, for whom it is recommended.

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

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from phase 1 testing
to real world distribution.

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Often it takes longer.

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The clinical trials are absolutely 
necessary to determine that a vaccine

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is safe and effective in preventing 
new infections.

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

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BridgeHIV.

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follow us on Twitter, or subscribe to this
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