Skip to Main Content

Public Health

Vetted resources and information on current public health events.

What is Monkeypox (MPOX)?

Monkeypox is a viral zoonosis (a virus transmitted to humans from animals) from the same group of viruses as Smallpox (Variola Virus). The symptoms are similar to those seen in the past in smallpox patients, although it is generally less severe. Monkeypox primarily occurs in central and west Africa, often in proximity to tropical rainforests, and has been increasingly appearing in urban areas. There are two clades of MPXV, the Congo Basin clade and the West African clade. The Congo Basin clade is clinically more severe with a 10% fatality rate. The West African clade has a case fatality rate of 1%. The current outbreak is caused by the West African clade.

Symptoms of monkeypox can include:

  • Fever
  • Headache
  • Muscle aches and backache
  • Swollen lymph nodes
  • Chills
  • Exhaustion
  • 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.

In the current outbreak, lesions on genitalia and perianal lesions have been more common due to the current role of sexual contact transmission. The classical prodromal symptoms (headache, muscle aches, fatigue etc.) are not always present in the current outbreak, and many patients present with a rash or typical lesions with or without fever. This can lead providers to misdiagnosis or confusion with other STIs such as syphilis or herpes.

Recent case reports demonstrate the potential for asymptomatic cases and transmission.

The virus can spread from person-to-person through:

  • Respiratory droplets
  • Direct contact with the infectious rash, scabs, or body fluids
  • 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

The virus enters the body through broken skin, the respiratory tract, and other non-respiratory mucous membranes (rectum, eyes, genitals, and the oral cavity).

Monkeypox can spread from the time symptoms start until the rash has fully healed and a fresh layer of skin has formed, and humans can be contagious before a visible rash appears and continue shedding the virus weeks after symptoms has dissipated. The illness typically lasts 2-4 weeks. People who do not have monkeypox symptoms cannot spread the virus to others.


The basic reproductive number (R0) for MPXV, which indicates the average number of new infections arising from a single infected individual in the entire population, is estimated to be between 0.59 and 0.96. Based on smallpox cross-immunity data from the Democratic Republic of the Congo, the maximum R0 is 1.25. However, it is believed that the transmission rate of MPXV has increased over time as less of the population has vaccine-derived immunity to smallpox. Several aspects of the current outbreak, including significant transmission between MSM, as well as several identified mutations that could enhance transmissibility compared to previous West African clade viruses, have made it difficult to know the current R0 for this outbreak.

Scientists are still trying to determine if transmission rates are affected by route of exposure, and if aerosols are more infectious than direct skin-to-skin contact.

Infectious Dose

While the infectious dose of MPXV in humans is unknown, based on studies in non-human primates the infectious dose from inhalation is estimated to be between 10 and 10,000 infectious viral particles. However, most of these studies were conducted in Congo Basin MPXV strain. The West African clade has generally been found to be less infectious than the Congo Basin clade.

The mean incubation period (interval from infection to onset of symptoms) of Monkeypox is 7 to 17 days but can range from 1 to 31 days.

The infection can be divided into two periods:

  1. Fever Period (lasts between 0–5 days)
  • Characterized by fever, intense headache, lymphadenopathy (swelling of the lymph nodes), back pain, myalgia (muscle aches) and intense asthenia (lack of energy).
  • Lymphadenopathy is a distinctive feature of monkeypox compared to other diseases that may initially appear similar (chickenpox, measles, smallpox)
  1. Rash Period (usually begins within 1–3 days of appearance of fever)
  • The rash tends to be more concentrated on the face and extremities rather than on the trunk. It affects the face (in 95% of cases), and palms of the hands and soles of the feet (in 75% of cases).
  • Also affected are oral mucous membranes (in 70% of cases), genitalia (30%), and conjunctivae (20%), as well as the cornea.
  • The rash evolves sequentially from macules (lesions with a flat base) to papules (slightly raised firm lesions), vesicles (lesions filled with clear fluid), pustules (lesions filled with yellowish fluid), and crusts which dry up and fall off. The number of lesions varies from a few to several thousand. In severe cases, lesions can coalesce until large sections of skin slough off.

The time from exposure to fever onset ranges from 10-14 days and from exposure to rash onset ranges from 12-16 days. This is an exceptionally long incubation period!

Monkeypox can be mistaken for other conditions that present with rash, but it has a few distinguishing characteristics:

  • Lesions are deep-seated, well-circumscribed, and umbilicated (having a small depression like a navel).
  • Lesions are contained in a single body area and are usually the same size and in the same stage of development.
  • The rash is centrifugal (appearing more on the extremities or face).
  • Lesions can appear on the palms or soles.
  • A fever appears before the rash, and lymphadenopathy is common.

There are no treatments specifically for monkeypox virus infections. However, monkeypox and smallpox viruses are genetically similar, which means that antiviral drugs and vaccines developed to protect against smallpox may be used to prevent and treat monkeypox virus infections.

Cidofovir, brincidofovir, and tecovirimat have proven activity against poxviruses in in vitro and animal studies. Only limited efficacy data are available for these drugs. In at least one small case study, tecovirimat decreased hospitalization time from more than 3 weeks to 10 days in the one patient who received the drug.

Antivirals, such as tecovirimat (TPOXX), may be recommended for people who are more likely to get severely ill, like patients with weakened immune systems. (CDC, 2022)

Monkeypox Vaccines

Vaccination is an important tool in preventing the spread of monkeypox. Because there are limitations in our knowledge about the effectiveness of these vaccines, people who are vaccinated are encouraged to continue to protect themselves from infection by avoiding close, skin-to-skin contact, including intimate contact, with someone who has monkeypox.

Who Should Get Vaccinated

In the current outbreak, you may want to get vaccinated if:

  • You might have already been exposed to monkeypox if:
    • You have been identified as a close contact of someone with monkeypox.
    • You learn that one of your sex partners in the past 2 weeks has been diagnosed with monkeypox.
    • You are a man who has had sex with other men, or if you are a transgender or nonbinary person, and in the past 2 weeks you have had:
      • Sex with multiple partners or group sex.
      • Sex at a commercial sex venue (like a sex club or bathhouse).
      • Sex at an event, venue, or in an area where monkeypox transmission is occurring.
  • You might be exposed to monkeypox in the future, if:
    • You are a man who has sex with other men, or if you are a transgender or nonbinary person and in the past 6 months have had any of the following:
      • A new diagnosis of one or more sexually transmitted diseases including acute HIV, chancroid, chlamydia, or gonorrhea
      • More than one sex partner.
    • You are a person who in the past 6 months has had any of the following:
      • Sex at a commercial sex venue (like a sex club or bathhouse)
      • Sex at an event, venue, or in an area where monkeypox transmission is occurring.
    • You are a person whose sexual partner identifies with any of the above scenarios.
    • You are a person who anticipates experiencing any of the above scenarios. 

There are currently two vaccines that may be used for the prevention of Monkeypox virus infection:

  • JYNNEOS (also known as Imvamune or Imvanex), licensed (or approved) by the U.S. Food and Drug Administration (FDA) for the prevention of Monkeypox virus infection.
  • ACAM2000, licensed (or approved) by FDA for use against smallpox and made available for use against monkeypox under an Expanded Access Investigational New Drug (EA-IND) protocol.


JYNNEOS is a third-generation vaccine based on a live, attenuated non-replicating orthopoxvirus, Modified Vaccinia Ankara (MVA). MVA is a live virus that does not replicate efficiently in humans. JYNNEOS is known internationally as Imvamune or Imvanex, and is manufactured by Bavarian Nordic.

Because of its safety profile, JYNNEOS vaccine should be prioritized for people who are at high risk for severe disease caused by infection with the Monkeypox virus (including, but not limited to, people with human immunodeficiency virus (HIV) infection or other immunocompromising conditions, who are pregnant, or who are at increased risk for serious adverse events following ACAM2000 vaccination).

The U.S. Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) in August 2022 to allow for use of JYNNEOS vaccine:

  • By intradermal injection for prevention of monkeypox disease in individuals 18 years of age and older determined to be at high risk for monkeypox infection, and
  • By subcutaneous injection for prevention of monkeypox disease in individuals younger than 18 years of age determined to be at high risk for monkeypox infection.

NOTE: The JYNNEOS vaccine is given as a two-dose series. The two doses should be given 28 days apart. CDC recommends getting both doses of JYNNEOS vaccine. The level of protection provided by only one dose is not known. CDC recommends getting your second dose on time. But, if you are unable to, get it as soon as you can, preferably within 35 days after the first dose.

You are considered vaccinated against monkeypox 14 days after you receive your second vaccine dose.


ACAM2000 is a second-generation vaccine indicated for the prevention of smallpox disease. It has been made available for use against monkeypox in the current outbreak under an Expanded Access Investigational New Drug (EA-IND) protocol, which requires informed consent along with completing additional forms. ACAM2000 contains a live vaccinia virus that is replication-competent in humans. ACAM2000 is manufactured by Emergent BioSolutions.

  • Available evidence supporting the use of smallpox vaccine for monkeypox prevention is derived from the vaccine used during smallpox eradication, Dryvax. Dryvax was a first-generation smallpox vaccine manufactured by Wyeth laboratories that is no longer available. Routine use of this vaccine was stopped in 1972 after smallpox was eradicated from the United States. The license was withdrawn in 2008 and no supplies of this vaccine remain.
  • The United States has a large supply of ACAM2000, but this vaccine has more side effects and contraindications than JYNNEOS.
  • ACAM2000 vaccine is recommended as a single dose given by multiple pricks to the skin using a special needle. You are considered vaccinated against monkeypox 28 days after getting the single vaccine dose.


NOTE: ACAM2000 vaccine contains a live virus called Vaccinia virus that can be spread to others. Vaccinia virus is in the same family of viruses as the viruses that cause monkeypox or smallpox, which is why it can help protect against monkeypox.

Following vaccination, a lesion or sore (known as a “take”) will form at the site of the vaccination. The lesion may take up to several weeks or more to heal. If you get ACAM2000, you need to take special care of the lesion site to prevent spread of the Vaccinia virus to others or to other parts of your body during this time.

WHO Public Health Emergency

Fifth Meeting of the International Health Regulations (2005) (IHR) Emergency Committee on the Multi-Country Outbreak of mpox (monkeypox)

11 May 2023 | Statement

The WHO Director-General transmits the report of the fifth meeting of the International Health Regulations (2005) (IHR) Emergency Committee regarding the multi-country outbreak of mpox (monkeypox), held on Wednesday 10 May from 12:00 to 17:00 CET.

The Emergency Committee acknowledged the progress made in the global response to the multi-country outbreak of mpox and the further decline in the number of reported cases since the last meeting. The Committee noted a significant decline in the number of reported cases compared to the previous reporting period and no changes in the severity and clinical manifestation of the disease. The Committee acknowledged remaining uncertainties about the disease, regarding modes of transmission in some countries, poor quality of some reported data, and continued lack of effective countermeasures in the African countries, where mpox occurs regularly. The Committee considered, however, that these are long-term challenges that would be better addressed through sustained efforts in a transition towards a long-term strategy to manage the public health risks posed by mpox, rather than the emergency measures inherent to a public health emergency of international concern (PHEIC).

The Committee emphasised the necessity for long-term partnerships to mobilize the needed financial and technical support for sustaining surveillance, control measures and research for the long-term elimination of human-to-human transmission, as well as mitigation of zoonotic transmissions, where possible. Integration of mpox prevention, preparedness and response within national surveillance and control programmes, including for HIV and other sexually transmissible infections, was reiterated as an important element of this longer-term transition. In particular, the Committee noted that the gains in control of the multi-country outbreak of mpox have been achieved largely in the absence of outside funding support and that longer-term control and elimination are unlikely unless such support is provided. These sustained investments will, in the long run, save money and lives, and reduce the risk of a global resurgence of mpox, as well as the risk of reverse zoonosis resulting in new areas where the virus may circulate.

The WHO Director-General expresses his gratitude to the Chair, Members, and Advisors for their advice and concurs with this advice that the event no longer constitutes a PHEIC for the reasons detailed in the proceedings of the meeting below and issues revised Temporary Recommendations for the transition period, which are presented at the end of this document.

Risk Assessments

Global Rapid Risk Assessment: Update

On 5 May, WHO updated its global Rapid Risk Assessment (RRA) for mpox.

Each of the WHO regional offices conducted a regional rapid risk assessment and a global document was compiled including all regional and global elements.

The public health risk at the global level continues to be assessed as moderate; the regional risk is assessed as moderate in four regions (AFR, AMR, EMR and EUR) and low in two regions (SEAR and WPR), based on the region-specific risk assessments. The level of confidence globally in the available information is moderate. (Table 3)

Table 3. Level of assessed mpox risk and the confidence in available information, by WHO region, as per updated global RRA (May 5, 2023).
Region Risk Assessment Confidence in Assessment
African Region Moderate Low
Region of the Americas Moderate Moderate
Eastern Mediterranean Region Moderate Low
European Region Moderate Moderate
Southeast Asia Region Low Moderate
Western Pacific Region Low Moderate

Overall, as the acute outbreak subsides, there is a need for an agreed approach between regions, disease control programmes, and a necessity to mobilize the resources required to support mpox control and elimination of person-to-person transmission of this infectious disease over the long-term. Although in the last year sustained transmission has not been observed in risk groups outside men who have sex with men (MSM) in newly affected countries, the decline of public health attention towards the disease might increase the risk of continuing undetected transmission, especially among groups at high risk for severe disease such as immunocompromised individuals, with the potential of more rapid virus evolution and adaptation. This remains a particular risk in low-income settings as well as for regions that did not experience a significant outbreak in 2022.

The event continues to evolve and therefore this risk assessment may be updated as new information becomes available. WHO is preparing a new overarching global strategy for mpox elimination and control and a country planning guide to support risk assessment and mitigation through the next stages of outbreak preparedness and response for elimination of human-to-human transmission.

WHO Emergency Situational Reports

Multi-country outbreak of mpox, External Situation Report #31
Data as received by WHO national authorities by 17:00 CEST, 30 November 2023
Laboratory Confirmed Cases 92,783
Deaths 171
Countries/Areas/Territories Affected 116
WHO Long Term Risk Assessment
  • The risk for the general population in countries with historical mpox transmission and their neighbouring countries is assessed as moderate.
  • The risk for gay men, bisexual men, other men who have sex with men, trans and gender diverse people, and sex workers, is assessed as moderate.
  • The risk for the general population in countries not affected prior to the current outbreak is assessed as low.
  • A total of 906 new laboratory-confirmed cases of mpox were reported globally in November 2023 from 26 countries.
  • The most affected regions, ordered by number of laboratory-confirmed cases, were the WHO Region of the Americas, the European Region, the Western Pacific Region, the South-East Asia Region and the African Region.
  • Based on the data reported through global surveillance, the mpox outbreak continues in most WHO regions, at a low level of transmission in the Western Pacific and South-East Asia, while more extensive transmission is observed in the European Region and in the Region of the Americas.
  • The African region shows a relatively low case count of laboratory-confirmed cases. The section of the report focusing on the Democratic Republic of the Congo illustrates the high level of transmission occurring in the country as reflected by the high number of suspected (clinically compatible) cases reported.
  • This issue provides a special focus on a report received of a case of mpox on a thematic cruise, highlighting the continued risk that gatherings and events which include sexual contact might represent in amplifying the ongoing global outbreak.
  • This report also includes a summary of a WHO mission to the Democratic Republic of the Congo conducted in collaboration with national counterparts and partners to assess the mpox situation in the country.