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Smallpox Vaccine and Monkeypox

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NOTE: Health professionals should consult the Guidance for Use of Smallpox Vaccine, Cidofovir, & VIG.

Monkeypox is a rare disease caused by the monkeypox virus, a member of the same group of viruses as smallpox virus. The monkeypox virus can spread from animals to humans and sometimes from one person to another. In humans, monkeypox causes fever, headache, backache, and swollen lymph nodes, followed by a blister-like rash. In some cases, monkeypox can cause death.

Monkeypox in the United States
In early June 2003, monkeypox was reported among several people in the United States who got sick after having contact with sick pet prairie dogs. This is the first outbreak of human monkeypox in the United States.

Monkeypox and Smallpox Vaccine
Because the monkeypox virus is related to the virus that causes smallpox, the smallpox vaccine can protect people from getting monkeypox as well as smallpox.

  • Smallpox vaccine is effective at protecting people against monkeypox when it is given before they are exposed to monkeypox. (Exposure includes very close contact with a person or animal that has monkeypox.)
  • Experts believe that vaccination after exposure to monkeypox may help prevent the disease or make it less severe.

People Who Should Get Smallpox Vaccine to Prevent Monkeypox
The smallpox vaccine is the best way to prevent monkeypox in someone who is exposed. For this reason, the following people should get the vaccine:

  • People who are investigating animal or human monkeypox cases (for example, public health and animal control workers).
  • Health-care workers who are caring for monkeypox patients, may be asked to care for monkeypox patients, or have been in close contact with monkeypox patients in the last 4 days. (Vaccination should be considered up to 14 days after exposure.)
  • Anyone who has had close contact with someone who is sick with monkeypox within the last 4 days. (Vaccination should be considered up to 14 days after exposure.)
  • Anyone (including veterinarians and veterinary technicians) who has had direct physical contact within the last four days with an infected animal acquired since April 15, 2003, in affected areas of the United States. (Vaccination should be considered up to 14 days after exposure.)
  • Lab workers who handle specimens that may contain monkeypox virus. (More information for lab workers can be found in the Interim Biosafety Guidelines for Laboratory Personnel Handling Human and Animal Specimens for Monkeypox Testing .)

People Who Should Not Get Smallpox Vaccine Even After Monkeypox Exposure

  • People with weakened immune systems should not get the smallpox vaccine, even if they have been exposed to monkeypox. (Cancer treatment, an organ transplant, HIV infection, Primary Immune Deficiency disorders, some severe autoimmune disorders, and medications to treat autoimmune disorders and other illnesses can weaken the immune system.)
  • People with life-threatening allergies to latex or to the smallpox vaccine or any of its ingredients (polymyxin B, streptomycin, chlortetracycline, neomycin) should not get the smallpox vaccine.

Anyone else who has been exposed to monkeypox in the past 14 days should get the smallpox vaccine, including children under 1 year of age, pregnant women, and people with skin conditions.

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