Mpox in the United States Fast Facts

Here's a look at mpox, formerly known as monkeypox, in the United States. In 2022, an outbreak was declared a public health emergency of international concern by the World Health Organization (WHO). The virus originated in Africa and is the cousin of the smallpox virus.

In November 2022, WHO renames the monkeypox virus as mpox after working with International Committee on the Taxonomy of Viruses (ICTV) to rename the the virus using non-stigmatizing, non-offensive social and cultural nomenclature.

(Source: Centers for Disease Control and Prevention)

Mpox is a poxvirus. It generally causes pimple- or blister-like lesions and flu-like symptoms such as fever. The disease is rarely fatal.

Mpox spreads through close contact. This includes direct physical contact with lesions as well as "respiratory secretions" shared through face-to-face interaction and touching objects that have been contaminated by mpox lesions or fluids. The virus may also pass to a fetus through the placenta.

Anyone can become ill from mpox, but the US Centers for Disease Control and Prevention (CDC) says that more than 99% of mpox cases in the United States in the 2022 outbreak have been among men who have sex with men. However, mpox is not generally considered a sexually transmitted disease.

Mpox is usually found in West and Central Africa, but additional cases have been seen in Europe, including the United Kingdom, and other parts of the world in recent years. Those cases are typically linked to international travel or imported animals infected with the poxvirus.

CDC Mpox Map and Case Count

WHO Situation Reports

1958 - Mpox is discovered when monkeys kept for research cause two outbreaks in Copenhagen, Denmark.

1970 - The first human case is recorded in Zaire (now the Democratic Republic of Congo).

2003 - An outbreak in the United States is linked to infected pet prairie dogs imported from Ghana and results in more than 80 cases.

July 16, 2021 - The CDC and local health officials in Dallas announce they are investigating a case of mpox in a traveler from Nigeria. "The individual is a City of Dallas resident who traveled from Nigeria to Dallas, arriving at Love Field airport on July 9, 2021. The person is hospitalized in Dallas and is in stable condition," the Dallas County Department of Health and Human Services says in a statement.

May 17, 2022 - The first confirmed US case of mpox in the 2022 outbreak is reported to the CDC in a traveler who returned to Massachusetts from Canada.

May 19, 2022 - WHO reports that death rates of the outbreak have been between 3% and 6%.

May 23, 2022 - The CDC announces the release of mpox vaccine doses from the nation's Strategic National Stockpile for "high-risk people." In the United States, the two-dose Jynneos vaccine is licensed to prevent smallpox and specifically to prevent mpox.

May 26, 2022 - CDC Director Dr. Rochelle Walensky announces that the United States is distributing the vaccine to states with reported cases and recommends vaccination for people at highest risk of infection due to direct contact with someone who has mpox.

June 22, 2022 - The CDC announces a partnership with five commercial laboratories to ramp up testing capacity in the United States.

June 23, 2022 - New York City launches the first mpox vaccination clinic in the United States.

June 28, 2022 - The US Department of Health and Human Services (HHS) and the Biden administration announce an enhanced vaccination strategy and report that more than 9,000 doses of vaccine have been distributed to date.

July 22, 2022 - Two American children contract mpox - a first in the United States. According to the CDC, the two cases are unrelated.

July 23, 2022 - WHO declares mpox a public health emergency of international concern, "an extraordinary event that may constitute a public health risk to other countries through international spread of disease and may require an international coordinated response."

July 27, 2022 - After weeks of mpox vaccines being in limited supply, more than 786,000 additional doses are made available in the United States, according to HHS.

July 29, 2022 - New York declares a state disaster emergency in response to the mpox outbreak.

August 1, 2022 - California and Illinois declare states of emergency. California has reported more than 800 cases, while Illinois has had more than 500, according to data from the CDC.

August 2, 2022 - An mpox response team is created by the Biden administration. President Joe Biden names Robert Fenton from the Federal Emergency Management Agency (FEMA) as the White House national mpox response coordinator.

August 2, 2022 - A report from Spain's National Institute for Microbiology indicates two men, ages 31 and 44, who died from mpox in unrelated cases had both developed encephalitis, or swelling of the brain, which can be triggered by viral infections. Encephalitis is a very rare condition known to be associated with mpox. It has been reported in people with mpox in West Africa and in a patient in the United States in 2003 during the small outbreak linked to imported prairie dogs.

August 4, 2022 - The Biden administration declares the mpox outbreak a national public health emergency.

August 5, 2022 - A report published by the CDC finds that 94% of cases were among men who had recent sexual or close intimate contact with another man. Further, 54% of cases were among Black Americans and Latinos.

August 9, 2022 - In an effort to stretch the limited supply of the Jynneos mpox vaccine, federal health officials authorize administering smaller doses using a different method of injection. The new injection strategy allows health-care providers to give shallow injections intradermally, in between layers of the skin, with one-fifth the standard dose size instead of subcutaneously, into the fatty layer below the skin, with the larger dose.

August 18, 2022 - The White House announces the acceleration of the HHS vaccine distribution timeline, with an additional 1.8 million doses of the Jynneos vaccine being made available. Additional vaccines will be distributed to communities hosting large LGBTQI+ events.

August 19, 2022 - Washington's King County, which includes Seattle, declares mpox a public health emergency, with more than 270 recorded cases.

September 12, 2022 - The first US death due to mpox is confirmed in Los Angeles County, California.

May 11, 2023 - WHO declares the mpox outbreak is no longer a global health emergency.

October 26, 2023 - CDC's Advisory Committee on Immunization Practices, or ACIP, votes unanimously to recommend that certain individuals ages 18 and older who are at high risk for getting mpox continue to get the vaccine as a routine part of their sexual health care.