The physical space of the MSK Library is permanently closed to visitors as of Friday, May 17, 2024. Please visit this guide for more information.
The physical space of the MSK Library is permanently closed to visitors as of Friday, May 17, 2024. Please visit this guide for more information.
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:
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:
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.
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:
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:
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)
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.
In the current outbreak, you may want to get vaccinated if:
There are currently two vaccines that may be used for the prevention of Monkeypox virus infection:
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:
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.
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.
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.
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)
| 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.
| Laboratory Confirmed Cases | 92,783 |
| Deaths | 171 |
| Countries/Areas/Territories Affected | 116 |
| WHO Long Term Risk Assessment | |
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