Smallpox Q & A
What should I know about Smallpox?
Vaccination is not recommended, and the vaccine is not available to health
providers or the public. In the absence of a confirmed case of smallpox anywhere
in the world, there is no need to be vaccinated against smallpox. There also can
be severe side effects to the smallpox vaccine, which is another reason we do
not recommend vaccination. In the event of an outbreak, the CDC has clear
guidelines to swiftly provide vaccine to people exposed to this disease. The
vaccine is securely stored for use in the case of an outbreak. In addition,
Secretary of Health and Human Services Tommy Thompson recently announced plans
to accelerate production of a new smallpox vaccine.
Are we expecting a smallpox attack?
We are not expecting a smallpox attack, but the recent events that include
the use of biological agents as weapons have heightened our awareness of the
possibility of such an attack.
Is there an immediate smallpox threat?
At this time we have no information that suggests an imminent smallpox
threat.
If I am concerned about a smallpox attack, can I go to my doctor and request
the smallpox vaccine?
The last naturally acquired case of smallpox occurred in 1977. The last cases
of smallpox, from laboratory exposure, occurred in 1978. In the United States,
routine vaccination against smallpox ended in 1972. Since the vaccine is no
longer recommended, the vaccine is not available. The CDC maintains an emergency
supply of vaccine that can be released if necessary, since post-exposure
vaccination is effective.
Are there plans to manufacture more vaccine in case of a bioterrorism attack
using smallpox?
Yes. In 2000, CDC awarded a contract to a vaccine manufacturer to produce
additional doses of smallpox vaccine.
If someone comes in contact with smallpox, how long does it take to show
symptoms?
The incubation period is about 12 days (range: 7 to 17 days) following
exposure. Initial symptoms include high fever, fatigue, and head and back aches.
A characteristic rash, most prominent on the face, arms, and legs, follows in
2-3 days. The rash starts with flat red lesions that evolve at the same rate.
Lesions become pus-filled after a few days and then begin to crust early in the
second week. Scabs develop and then separate and fall off after about 3-4 weeks.
Is smallpox fatal?
The majority of patients with smallpox recover, but death may occur in up to
30% of cases.
How is smallpox spread?
In the majority of cases, smallpox is spread from one person to another by
infected saliva droplets that expose a susceptible person having face-to-face
contact with the ill person. People with smallpox are most infectious during the
first week of illness, because that is when the largest amount of virus is
present in saliva. However, some risk of transmission lasts until all scabs have
fallen off.
Contaminated clothing or bed linen could also spread the virus. Special
precautions need to be taken to ensure that all bedding and clothing of patients
are cleaned appropriately with bleach and hot water. Disinfectants such as
bleach and quaternary ammonia can be used for cleaning contaminated surfaces.
If someone is exposed to smallpox, is it too late to get a vaccination?
If the vaccine is given within 4 days after exposure to smallpox, it can
lessen the severity of illness or even prevent it.
If people got the vaccination in the past when it was used routinely, will
they be immune?
Not necessarily. Routine vaccination against smallpox ended in 1972. The
level of immunity, if any, among persons who were vaccinated before 1972 is
uncertain; therefore, these persons are assumed to be susceptible. For those who
were vaccinated, it is not known how long immunity lasts. Most estimates suggest
immunity from the vaccination lasts 3 to 5 years. This means that nearly the
entire U.S. population has partial immunity at best. Immunity can be boosted
effectively with a single revaccination. Prior infection with the disease grants
lifelong immunity.
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