Clinical Trials
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Understanding Vaccine
Clinical Trials
What is a Vaccine Clinical Trial?
Experimental vaccines are first tested in laboratory
and animal studies for safety and immunogenicity. If the results
are favorable, a vaccine must successfully complete several
phases of testing in people before it can gain Food and Drug
Administration (FDA) approval for licensing and marketing
to the public. All the phases conduct randomized, controlled,
and double-blinded studies. These studies compare the safety
and effectiveness of the vaccine to an inactive placebo or
a control that may be another licensed vaccine of potential
benefit to the study population. *
Phases of Clinical Trials
A Phase I trial is the first setting in
which an experimental vaccine is given to people. The trial,
which can last up to 2 years, may enroll between 20 to 100
volunteers. A Phase I trial primarily seeks information on
safety, particularly looking for any vaccine-related side
effects. The trial can also provide data on the dose and administration
schedule needed to achieve the optimal immune responses.
Once Phase I trials show the experimental vaccine
is safe, well tolerated, and appears promising, it can advance
into Phase II. These trials, which can last longer
than 2 years, enroll between 100 to 300 volunteers. In these
trials researchers gather more data on safety and immunogenicity.
Investigators supported by the National Institute
of Allergy and Infectious Diseases (NIAID) are also developing
designs for intermediate trials that can provide preliminary
answers about a candidate vaccine's efficacy, and determine
if the vaccine candidate should move forward into large Phase
III, or efficacy, trials. A Phase IIb trial, also
known as a "proof-of-concept" trial, is smaller,
usually requiring 2,000 to 9,000 volunteers, and may provide
clues about the immune responses that can protect against
disease.
The most promising vaccine candidates move into
Phase III, enrolling 10,000 or more people. A Phase
III trial, which can last up to 4 years, is typically designed
to ensure enough data are collected on safety and effectiveness
to support a license application to FDA. *
Continue here for additional Clinical
Trials Resource Information.
* Courtesy National Institute of Allergy and Infectious
Diseases
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