Smallpox: Frequently Asked Questions - Parent Handout

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What are the AAP smallpox vaccine recommendations?

  • Barring an outbreak of smallpox or evidence of imminent release, the AAP recommends that smallpox vaccine not be made available to the general public.
  • The Academy supports ring vaccination as the most efficient use of smallpox vaccine with the fewest number of adverse side effects. The strategy is based on information that vaccination within three to four days of contact with an infectious case can prevent or lessen the severity of the disease.
  • In the ring vaccination strategy, contacts of people with smallpox and contacts of these contacts would be vaccinated immediately. This would form concentric "rings" of immunized people around quarantined infectious cases. This will reduce the chance of transmission to susceptible people.

If a terrorist attack or threat makes routine immunization necessary, would the U.S. be ready?

  • Currently, there is enough vaccine to immunize the entire U.S. population.
  • Currently, approximately 15 million doses of vaccine are stocked in a dried, frozen state by the CDC. Data suggest that the vaccine may be diluted at least 1:5 to 1:10 and still provide a satisfactory response. Additionally, about 85 million doses of concentrated smallpox vaccine put aside by Aventis Pasteur are available to the CDC.
  • The vaccine that is stored at the CDC has recently been licensed by the U.S. Food and Drug Administration, but it is not available to the general public. This limits the use of the vaccine unless a disaster were declared. The vaccine is not licensed for, and it has not been tested, in persons < 18 years of age.

Are we expecting a smallpox attack?

  • We are not expecting a smallpox attack, but the recent events that include the use of anthrax as a weapon 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.
  • The last naturally acquired case of smallpox in the U.S. occurred in 1949, and the last naturally acquired case in the world occurred in 1977. The last cases of smallpox, from laboratory exposure, occurred in 1978. However, reports that smallpox virus may have been given to facilities other than the designated laboratories in the US and Russia is the source of some concern about the possibility of a threat.

If I am concerned about a smallpox attack, can I go to my doctor and request the smallpox vaccine?

  • In the United States, routine vaccination against smallpox ended in 1972. Since the vaccine is no longer recommended, the vaccine is not available for the general public.
  • The CDC maintains an emergency supply of vaccine that can be released if necessary. If the current administration so decides, smallpox vaccine may be made available to the general public. The President has indicated that there are plans to develop a method by which people who want the vaccine may receive it, but no vaccine for this purpose is presently available.

If I want the smallpox vaccine and I'm willing to accept the risks, why shouldn't I be allowed to have it?

  • The smallpox vaccine causes each person who gets it to develop a sore or "pock" at the point of injection that is teeming with the virus. That person is now contagious for up to 21 days.
  • The virus can spread from a recently immunized person to other people. Those at particularly high risk for adverse reactions are young children, the elderly, and people who have altered immune systems from cancer, chemotherapeutic drugs, or AIDS. For all those people, the result could be a life-threatening or life-ending infection.
  • Complications of vaccination can usually be treated with vaccinia immune globulin but this is currently in limited supply.

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 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 backaches.
  • The characteristic rash, most prominent on the face, arms, and legs, follows in 2-3 days. The rash starts with flat, red sores that evolve at the same rate. The sores 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, possibly leaving pitted scars.

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 after the rash develops, 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 with an appropriate mixture of bleach and hot water. Disinfectants such as bleach and quaternary ammonia can be used for cleaning contaminated surfaces.

If people got the vaccination in the past when it was used routinely, will they be immune?

  • Probably not.
  • Routine vaccination against smallpox ended in 1972. The level of immunity, if any, among people who were vaccinated before 1972 is uncertain; therefore, these people 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. A single revaccination can effectively boost immunity.

Is it possible for people to get smallpox from the vaccination?

  • No, smallpox vaccine does not contain smallpox virus but another live virus called vaccinia virus. Since this virus is related to smallpox virus, vaccination with vaccina provides immunity against infection from smallpox virus.

How safe is the smallpox vaccine?

  • Smallpox vaccine is considered safe, however it is less safe than vaccines in current use. Some people with pre-existing conditions such as eczema or immune system disorders have a higher risk for having complications from the vaccine.
  • Adverse reactions have been known to occur that range from mild rashes to fatal brain infection and disseminated vaccina. In the absence of an outbreak of smallpox, smallpox vaccine should not be administered to people with a history or presence of eczema or other skin conditions, pregnant women, or people with immunodeficiency diseases and among those with suppressed immune systems as occurs with leukemia, lymphoma, generalized malignancy, or solid organ transplantation or people living in a family situation with an individual with one of these conditions.
  • Caution should be used in vaccinating individuals who have contact with people who are at high risk for complications, because the vaccine virus can spread from a vaccinated individual to an unvaccinated, high-risk individual.

Is there any treatment for smallpox?

  • There is no proven treatment for smallpox, but research to evaluate new antiviral agents is ongoing.
  • Patients with smallpox can benefit from supportive therapy (e.g., intravenous fluids, medicine to control fever or pain) and antibiotics for any secondary bacterial infections that may occur.

How can we stop the spread of smallpox after someone comes down with it?

  • Patients should be placed in medical isolation so that they will not continue to spread the virus. In addition, people who have come into close contact with smallpox patients should be vaccinated immediately and closely watched for symptoms of smallpox. Vaccine and isolation are the strategies for stopping the spread of smallpox.
  • Your doctor has access to guidelines prepared by the CDC for evaluating and responding to a suspected smallpox outbreak.



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