Phase I/II Trial of Modified Vaccinia Virus Ankara (MVA) Vaccine Against Smallpox
Status:
Completed
Trial end date:
2006-03-01
Target enrollment:
Participant gender:
Summary
This study will test the safety of an experimental vaccine called modified vaccinia virus
ankara (MVA) and determine if it confers protection against the smallpox virus (variola).
There is an existing vaccine, called Dryvax® (Registered Trademark), which is effective
against smallpox; however, this vaccine can cause various side effects, including some that,
on rare occasions, can be life-threatening. Dryvax® (Registered Trademark) has not been used
in the United States since childhood vaccination was stopped in 1971, and though it is given
to certain healthcare and laboratory workers, and some people in the armed forces, it is not
recommended for the general population. Both the MVA and Dryvax® (Registered Trademark)
vaccines are made using the vaccinia virus, which is closely related to variola.
Healthy normal volunteers between 31 and 60 years of age who have been vaccinated with a
smallpox vaccine more than 10 years before entering the study may be eligible for this
protocol. Candidates will be screened with a medical history, physical examination, and blood
and urine tests, including an HIV test and a pregnancy test for women of childbearing
potential.
Participants will receive MVA vaccine or placebo, followed by a dose of Dryvax® (Registered
Trademark). The MVA vaccine and placebo are injected into an arm muscle with a needle and
syringe. The Dryvax® (Registered Trademark) vaccine is administered with a special forked
needle that is poked lightly into the skin of the upper arm, usually 15 times, in a process
called scarification. When the vaccine works, a small pus-filled blister forms, followed by a
scab and then scarring at the site of the vaccination. The formation of the blister and scab
is called a take, indicating that the vaccine is effective and will protect against smallpox
for at least a few years. If scarification does not take, it can either mean that the person
already has immunity or that the vaccine did not work.
Study participants will be randomly assigned to one of the following dosing groups: 1) one
injection of MVA; 2) one injection of placebo; 3) two injections of MVA 4 weeks apart; or 4)
two injections of placebo 4 weeks apart. All participants will receive a challenge dose of
Dryvax® (Registered Trademark) 12 weeks after their last injection of MVA or placebo to
determine if the MVA vaccine has conferred immunity. A take, that occurs in response to the
Dryvax® (Registered Trademark) dose indicates lack of prior immunity, and thus tells whether
one or two doses of MVA is needed to produce an immune response.
Participants will be observed for at least 1 hour after each injection. They will come to the
clinic at least once a week after MVA or placebo injections and at least twice a week after
Dryvax® (Registered Trademark) to have the injection site evaluated and photographed. At each
visit, participants will be asked how they are feeling and what medications, if any, they are
taking. Blood and urine tests will be done according to the following schedule:
- Before each injection;
- 1 week after each injection;
- 4 weeks after the MVA or placebo injections are finished;
- At the time of the Dryvax® (Registered Trademark) dose;
- 4 weeks after the Dryvax® (Registered Trademark) dose;
- 12 weeks after the Dryvax® (Registered Trademark) dose.
Additional laboratory tests may be done between visits if medically necessary.
Phase:
Phase 1
Details
Lead Sponsor:
National Institute of Allergy and Infectious Diseases (NIAID)