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.
To stay in touch with Youreka science, like us on Facebook,
follow us on Twitter, or subscribe to this YouTube channel, or visit us at
YourekaScience.org
Thank you for watching!