Monkeypox is a rare disease caused by infection with the monkeypox virus. Monkeypox virus is part of the same family of viruses as variola virus, the virus that causes smallpox. Monkeypox symptoms are similar to smallpox symptoms, but milder, and monkeypox is rarely fatal. Monkeypox is not related to chickenpox.
Monkeypox was discovered in 1958 when two outbreaks of a pox-like disease occurred in colonies of monkeys kept for research. Despite being named “monkeypox,” the source of the disease remains unknown. However, African rodents and non-human primates (like monkeys) might harbor the virus and infect people.
The first human case of monkeypox was recorded in 1970. Prior to the 2022 outbreak, monkeypox had been reported in people in several central and western African countries. Previously, almost all monkeypox cases in people outside of Africa were linked to international travel to countries where the disease commonly occurs or through imported animals. These cases occurred on multiple continents.
Symptoms of monkeypox can include:
Muscle aches and backache
Swollen lymph nodes
A rash that can look like pimples or blisters that appears on the face, inside the mouth, and on other parts of the body, like the hands, feet, chest, genitals, or anus.
The rash goes through different stages before healing completely. The illness typically lasts 2-4 weeks. Sometimes, people get a rash first, followed by other symptoms. Others only experience a rash.
Monkeypox spreads in different ways. The virus can spread from person-to-person through:
direct contact with the infectious rash, scabs, or body fluids
respiratory secretions during prolonged, face-to-face contact, or during intimate physical contact, such as kissing, cuddling, or sex
touching items (such as clothing or linens) that previously touched the infectious rash or body fluids
pregnant people can spread the virus to their fetus through the placenta
It’s also possible for people to get monkeypox from infected animals, either by being scratched or bitten by the animal or by preparing or eating meat or using products from an infected animal.
Monkeypox can spread from the time symptoms start until the rash has fully healed and a fresh layer of skin has formed. The illness typically lasts 2-4 weeks. People who do not have monkeypox symptoms cannot spread the virus to others. At this time, it is not known if monkeypox can spread through semen or vaginal fluids.
Take the following steps to prevent getting monkeypox:
Avoid close, skin-to-skin contact with people who have a rash that looks like monkeypox.
Do not touch the rash or scabs of a person with monkeypox.
Do not kiss, hug, cuddle or have sex with someone with monkeypox.
Do not share eating utensils or cups with a person with monkeypox.
Do not handle or touch the bedding, towels, or clothing of a person with monkeypox.
Wash your hands often with soap and water or use an alcohol-based hand sanitizer.
In Central and West Africa, avoid contact with animals that can spread monkeypox virus, usually rodents and primates. Also, avoid sick or dead animals, as well as bedding or other materials they have touched.
If you are sick with monkeypox:
- Isolate at home
- If you have an active rash or other symptoms, stay in a separate room or area away from people or pets you live with, when possible.
CDC recommends vaccination for people who have been exposed to monkeypox and people who are at higher risk of being exposed to monkeypox, including:
- People who have been identified by public health officials as a contact of someone with monkeypox
People who may have been exposed to monkeypox, such as:
- People who are aware that one of their sexual partners in the past 2 weeks has been diagnosed with monkeypox
- People who had multiple sexual partners in the past 2 weeks in an area with known monkeypox
People whose jobs may expose them to orthopoxviruses, such as:
- Laboratory workers who perform testing for orthopoxviruses
- Laboratory workers who handle cultures or animals with orthopoxviruses
- Some designated healthcare or public health workers
Two vaccines licensed by the U.S. Food and Drug Administration (FDA) are available for preventing monkeypox infection: JYNNEOS (also known as Imvamune or Imvanex) and ACAM2000.
In the United States, there is currently a limited supply of JYNNEOS, although more is expected in coming weeks and months.
There is an ample supply of ACAM2000. However, this vaccine should not be used in people who have some health conditions, including a weakened immune system, skin conditions like atopic dermatitis/eczema, or pregnancy.
No data are available yet on the effectiveness of these vaccines in the current outbreak.
People are considered fully vaccinated about 2 weeks after their second shot of JYNNEOS and 4 weeks after receiving ACAM2000. However, people who get vaccinated should continue to take steps to protect themselves from infection by avoiding close, skin-to-skin contact, including intimate contact, with someone who has monkeypox.
To better understand the protective benefits of these vaccines in the current outbreak, CDC will collect data on any side effects and whether the way the person was infected makes any difference in how well the vaccine protects them.
Monkeypox Vaccine Post-Exposure Prophylaxis (PEP):
For the current outbreak, this approach can be considered as “standard PEP” for monkeypox. People can be vaccinated following exposure to monkeypox to help prevent illness from monkeypox virus. It is important that states and other jurisdictions identify contacts of confirmed or probable monkeypox cases to offer vaccine for PEP and to monitor for any early signs of illness.
CDC recommends that the vaccine be given within 4 days from the date of exposure for the best chance to prevent onset of the disease.
If given between 4 and 14 days after the date of exposure, vaccination may reduce the symptoms of disease, but may not prevent the disease. However, when coupled with self-isolation and other prevention measures when symptoms first occur, PEP is important for controlling outbreaks and preventing further transmission of monkeypox.
Outbreak Response Monkeypox Vaccine Post-Exposure Prophylaxis (PEP)++:
For the current outbreak, this expanded approach can be considered as “individual-directed PEP” for monkeypox; public health officials refer to it as “expanded PEP” or “PEP plus-plus” or “PEP++”.
People with certain risk factors are more likely to have been recently exposed to monkeypox. The PEP++ approach aims to reach these people for post-exposure prophylaxis, even if they have not had documented exposure to someone with confirmed monkeypox.
When coupled with self-isolation and other prevention measures when symptoms first occur, PEP++ may help slow the spread of the disease in areas with large numbers of monkeypox cases—which would suggest a higher level of monkeypox virus transmission.
Monkeypox Vaccine Pre-Exposure Prophylaxis (PrEP):
This approach refers to administering vaccine to someone at high risk for monkeypox (for example, laboratory workers who handle specimens that might contain monkeypox virus).
At this time, most clinicians in the United States and laboratorians not performing the orthopoxvirus generic test to diagnose orthopoxviruses, including monkeypox virus, are not advised to receive monkeypox vaccine PrEP.
JYNNEOS vaccine is being allocated to jurisdictions for use for the following individuals:
Known contacts who are identified by public health via case investigation, contact tracing, and risk exposure assessments
Presumed contacts who may meet the following criteria:
Know that a sexual partner in the past 14 days was diagnosed with monkeypox
Had multiple sexual partners in the past 14 days in a jurisdiction with known monkeypox
JYNNEOS doses should be prioritized for those people who are at risk for severe adverse events with ACAM2000 or severe disease from monkeypox (such as people with HIV or other immunocompromising conditions).
JYNNEOS contains a live virus that does not replicate efficiently in human cells.
Administered as two subcutaneous injections four weeks apart.
The immune response takes 2 weeks after the second dose for maximal development.
Licensed by the FDA for use in the prevention of smallpox or monkeypox in people ages 18 years and older. Use in younger populations requires submission of a single patient Expanded Access Investigational New Drug (IND) application.
The effectiveness of JYNNEOS against monkeypox is supported by animal studies.
There are no data on the efficacy of JYNNEOS for PEP or PrEP from the current outbreak. Although this is also true for ACAM2000, there is evidence that the related Dryvax vaccine worked well during the smallpox eradication period. Public health officials have concern about the lack of efficacy data for JYNNEOS, especially because it requires two doses 28 days apart.
Adverse reactions include injection site reactions such as pain, swelling, and redness.
People with a severe allergy to any component of the vaccine (gentamicin, ciprofloxacin, egg protein) should not receive this vaccine.
Safe for administration to people with HIV and atopic dermatitis.
While there are no data in people who are pregnant or breastfeeding, animal data do not show evidence of reproductive harm; pregnancy and breastfeeding are not contraindications.
*On November 3, 2021, the Advisory Committee on Immunization Practices (ACIP) voted to recommend JYNNEOS pre-exposure prophylaxis as an alternative to ACAM2000 for certain persons at risk for exposure to orthopoxviruses.
ACAM2000 is a live Vaccinia virus vaccine that is replication competent.
Administered as one percutaneous dose via multiple puncture technique with a bifurcated needle.
The immune response takes 4 weeks for maximum development.
Following a successful inoculation, a lesion (known as a “take”) will develop at the site of the vaccination; the lesion may take up to 6 weeks or more to heal.
Licensed by the FDA for use against smallpox; allowed for use against monkeypox under an Expanded Access IND, which requires informed consent along with submission of additional forms.
The effectiveness of ACAM2000 is supported by human clinical trials and animal studies.
There are no data on the efficacy of ACAM2000 for PEP or PrEP from the current outbreak.
Adverse reactions include injection site pain, swelling, and redness; fever; rash; lymph node swelling; and complications from inadvertent inoculation.
People with severe allergy to any component of the vaccine should not receive it. In addition, people with severely weakened immune systems should not receive this vaccine.
ACAM2000 should not be given to people with the following conditions:
Eye disease treated with topical steroids
Congenital or acquired immune deficiency disorders, including those taking immunosuppressive medications and people living with HIV (regardless of immune status)
Atopic dermatitis/eczema and persons with a history of atopic dermatitis/eczema or other acute or exfoliative skin conditions
Infants less than 12 months of age
If You Have a New or Unexplained Rash or Other Symptoms…
Avoid sex or being intimate with anyone until you have been checked out by a healthcare provider.
If you don’t have a provider or health insurance, visit a public health clinic near you.
When you see a healthcare provider, wear a mask, and remind them that this virus is circulating in the area.
If You or Your Partner Have Monkeypox…
Follow the treatment and prevention recommendations of your healthcare provider.
Avoid sex or being intimate with anyone until the rash has healed, scabs have fallen off and you have a fresh layer of skin.
Recommendations for Health Departments
Please contact the CDC Monkeypox Call Center before sending specimens to CDC at firstname.lastname@example.org to report the case and obtain the case report form.
If monkeypox is suspected, CDC should be consulted through the CDC Emergency Operations Center (770-488-7100) or at email@example.com.
Appropriately collected samples can be sent to your Public Health Laboratory (Laboratory Response Network (LRN) laboratory) for testing by PCR.
Laboratory Response Network laboratories (LRN) can provide orthopoxvirus testing on lesion specimens that clinicians obtain from suspected monkeypox patients. If orthopoxvirus positive, further characterization of the specimen occurs at CDC. CDC requires dry swabs of lesion material, swabs of lesion material in VTM, or crusts.
When collecting specimens,
Vigorously swab or brush lesion with two separate sterile synthetic swabs (including, but not limited to polyester, nylon, or Dacron) with a plastic, wood, or thin aluminum shaft. Do not use cotton swabs. Collect multiple specimens for initial and secondary testing as follows:
Break off end of applicator of each swab into a 1.5- or 2-mL screw-capped tube with O-ring or place each entire swab in a separate sterile container that has a gasket seal and can be shipped under the required conditions. Two swabs from each lesion should be collected, preferably from different locations on the body or from lesions which differ in appearance. Swabs and other specimens should be placed in different containers. If using transport media, only VTM is accepted at CDC at this time; do not use universal transport media.
1. Centers for Disease Control and Prevention. (2022, June 30). Monkeypox. Centers for Disease Control and Prevention. Retrieved July 20, 2022, from https://www.cdc.gov/poxvirus/monkeypox/index.html