An ongoing outbreak of the viral disease monkeypox was confirmed in May 2022, beginning with a cluster of cases found in the United Kingdom. The first confirmed case was traced to an individual with travel links to Nigeria (where the disease is endemic) and was detected on 6 May 2022, although it has been suggested that cases were already spreading in the previous months. From 18 May onwards, cases were reported from an increasing number of countries and regions, predominantly in Europe, North and South America, Asia, Africa, and Australia. As of 15 July, there have been 12,590 confirmed cases. A total of 12 deaths have been confirmed as well. As of 27 June, the World Health Organization has declared this an “evolving health threat” rather than a Public Health Emergency of International Concern (PHEIC).
The outbreak marked the first time the disease has spread widely outside Central and West Africa. Cases have mainly but not exclusively been identified amongst men who have sex with men (MSM). Still, health authorities emphasized that anyone can catch the disease, particularly if they have close contact with a symptomatic person. Initial WHO assessments expressed the expectation of the outbreak to be contained and of low impact on the general population in affected countries. A more recent statement acknowledged that undetected transmission had occurred for some time. And called for urgent action to reduce transmission.
Monkeypox is a viral infection that manifests a week or two after exposure with fever and other non-specific symptoms and then produces a rash with blisters that can last for a couple of weeks before usually clearing up. In infections before the current outbreak, 1–3% of people with known diseases have died (without treatment). Cases in children are more likely to be severe.
Monkeypox is an infectious viral disease that can occur in humans and some other animals. Symptoms include fever, swollen lymph nodes, and a rash that forms blisters and then crusts over. The time from exposure to onset of symptoms ranges from 5 to 21 days. The duration of symptoms is typically 2 to 4 weeks. There may be mild symptoms, but they may occur without known symptoms. The classic presentation of fever and muscle pains, followed by swollen glands with lesions at the same stage, is not expected in all outbreaks. Cases may be severe, especially in children, pregnant women, or people with suppressed immune systems.
There is no known cure. A study in 1988 found that the smallpox vaccine was around 85% protective in preventing infection in close contact and lessening the severity of the disease. A newer smallpox and monkeypox vaccine based on modified vaccinia Ankara has been approved but with limited availability. Other measures include regular hand washing and avoiding sick people and other animals. Antiviral drugs may be used during outbreaks, including cidofovir and tecovirimat, vaccinia immune globulin, and the smallpox vaccine. The illness is usually mild, and most infected will recover within a few weeks without treatment. Estimates of the risk of death vary from 1% to 10%, although very few deaths as a consequence of monkeypox have been recorded since 2017.
Monkeypox is endemic to West and Central Africa. Before the 2022 outbreak, the United Kingdom had recorded only seven previous cases of monkeypox, all of which were imported issues from Africa or healthcare workers involved in their treatment. The first three such cases were in 2018, followed by a further point in 2019 And three more in 2021. The only major monkeypox outbreak recorded in a Western country before 2022 was the 2003 Midwest monkeypox outbreak in the United States. That one did not feature community transmission.
According to the World Health Organization, this outbreak is in the West African clade, with a reported case fatality rate of 1%. The genomic sequence of the virus associated with this outbreak was first published on 19 May by Portuguese researchers. They confirmed that the monkeypox virus was of the West African clade, related to other previous international outbreaks in 2018–19.
The 2022 outbreak has a different spread pattern than prior monkeypox outbreaks outside Africa. Genetic evidence suggests the outbreak likely started in Nigeria. Given the unusually high frequency of human-to-human transmission observed in this event and the probable community transmission without a history of traveling to endemic areas, the spread of the virus through close contact is more likely, with a message during sexual activities being the most common route. Most cases have been in men. A significant proportion of cases, although not all, are in men who have sex with men (MSM), notably in Canada, Spain, and the UK, with many cases diagnosed in sexual health clinics. Cases are primarily in young and middle-aged men. This points to transmission due to close contact during sex as one transmission route. The European Centre for Disease Prevention and Control (ECDC) considers the monkeypox virus moderately transmissible among humans. According to the center, the most common transmission among MSM who contracted the virus is likely through sexual activity due to intimate contact with infected skin lesions. The ECDC rates the likelihood of information due to close contact, including sexual contact, as “high,” but without close contact, the possibility of communication between individuals is considered low. In Nature, Anne Rimoin and Raina MacIntyre speculate that the higher percentage of MSM affected is a result of a coincidental introduction to the community and then sexual activity constituting “close contact” rather than the virus itself becoming sexually transmitted. Monkeypox is not primarily a sexually transmitted disease.
On 23 May, David Heymann, an advisor for the World Health Organization, said that the plausible theory of how the outbreak started was transmitted during sexual intercourse of gay and bisexual men at two raves in Belgium and Spain. On 25 May, The Guardian stated that many scientists suspect the disease was circulating in the UK and Europe before reaching the MSM community, possibly misdiagnosed or detected only in isolated cases; four cases were diagnosed in 2018 and 2019, all in individuals recently arrived from Nigeria.
The UK Human Animal Infections and Risk Surveillance (HAIRS) group warned that the virus could reach wildlife and become endemic.
Smallpox vaccines containing vaccinia, such as Imvanex (Jynneos), can provide around 85% effectiveness against monkeypox. This protection level is calculated from studies using smallpox vaccines tested in late 1980 in Africa. The UKHSA has begun using Imvanex as post-exposure prophylaxis for close contact with known cases. According to the CDC, the vaccination with Jynneos/Imvanex is “[a]dministered as two subcutaneous injections four weeks apart.”
On 25 May, disease experts from the NICD in South Africa said they saw no need for mass vaccination because they believe cases will not explode as they did in the COVID-19 pandemic.
In reaction to the current outbreak of monkeypox, several countries have stated they are buying vaccines and releasing vaccines from national stockpiles for use in the episode as there is a new concern of vaccine shortage as the demand for vaccines exceeds the supply. In May 2022, the US, Spain, Germany and the UK All announced purchases of smallpox vaccine.
On 24 May, Centers for Disease Control (CDC) Deputy Director Jennifer McQuiston confirmed the United States is releasing some of their Jynneos vaccine supply from their Strategic National Stockpile for people who are “high-risk.”
On 23 June, the New York City Department of Health announced a clinic at the Chelsea Sexual Health Clinic to offer the two-dose JYNNEOS vaccine to “…all gay, bisexual, and other men who have sex with men (cisgender or transgender) ages 18 and older who have had multiple or anonymous sex partners in the last 14 days.”