What is the smallpox vaccine, and is it still required?
The smallpox vaccine is the only
way to prevent smallpox. The vaccine is made from a virus
called vaccinia, which is another pox-type virus related to
smallpox. The vaccine helps the body develop immunity to
smallpox. It was successfully used to eradicate smallpox from
the human population.
Routine vaccination of the
American public against smallpox stopped in 1972 after the
disease was eradicated in the United States. Until recently,
the U. S. government provided the smallpox vaccine only to a
few hundred scientists and medical professionals who work with
smallpox and similar viruses in a research setting. After the
events of September and October, 2001, however, we have taken
extensive actions to improve our level of preparedness against
terrorism. For smallpox, this included updating a response
plan and ordering enough smallpox vaccine to immunize the
American public in the event of a smallpox outbreak. The plans
are in place, and there is sufficient vaccine available to
immunize everyone who might need it in the event of an
Should I get vaccinated against smallpox?
The smallpox vaccine is not
available to the general public at this time. If vaccination
is considered advisable, you will be notified quickly.
How is the vaccine given?
The smallpox vaccine is not
given with a hypodermic needle. It is not a shot, like many
vaccinations. The vaccine is given using a bifurcated
(two-pronged) needle that is dipped into the vaccine solution.
When removed, the needle retains a droplet of the vaccine. The
needle is then used to prick the skin 15 times in a few
seconds. The pricking is not deep, but it will cause a sore
spot and one or two drops of blood to form. The vaccine
usually is given in the upper arm.
If the vaccination is
successful, a red and itchy bump develops at the vaccination
site in three or four days. In the first week after
vaccination, the bump becomes a large blister, fills with pus,
and begins to drain. During week two, the blister begins to
dry up and a scab forms. The scab falls off in the third week,
leaving a small scar. People who are being vaccinated for the
first time have a stronger reaction than those who are being
If someone is exposed to smallpox, is it too late to get a
Vaccination within 3 days of
exposure will completely prevent or significantly modify
smallpox in the vast majority of persons. Vaccination 4 to 7
days after exposure likely offers some protection from disease
or may modify the severity of disease.
How long does a smallpox vaccination last?
Past experience indicates that
the first dose of the vaccine offers protection from smallpox
for 3 to 5 years, with decreasing immunity thereafter. If a
person is vaccinated again later, immunity lasts longer.
Are diluted doses of smallpox vaccine as effective?
Recent tests have indicated that
diluted smallpox vaccine is just as effective in providing
immunity as full-strength vaccine.
What is the smallpox vaccine made of?
The vaccine is made from a virus
called vaccinia, another pox-type virus related to smallpox.
The smallpox vaccine helps the body develop immunity to
Is it possible for people to get smallpox from the
No. The smallpox vaccine does
not contain smallpox virus and cannot spread or cause
smallpox. However, the vaccine does contain another virus
called vaccinia which is live in the vaccine. Because the
virus is alive, it can spread to other parts of the body or to
other people from the vaccine site. For that reason, the
vaccine site must be carefully monitored.
Is it possible to get vaccinia, the virus in the vaccine, from
someone who has recently been vaccinated?
Yes. Vaccinia is spread by
touching a vaccination site before it has healed or by
touching bandages or clothing that have become contaminated
with live virus from the vaccination site. Vaccinia is not
spread through airborne contagion. The vaccinia virus may
cause rash, fever, and head and body aches.
What are the symptoms of vaccinia?
The vaccinia virus may cause
rash, fever, and head and body aches.
How is vaccinia spread?
Vaccinia is spread by touching a
vaccination site before it has healed or by touching bandages
or clothing that have become contaminated with live virus from
the vaccination site. Vaccinia is not spread through the air.