According to the US Centres for Disease Control and Prevention (CDC), around 2,225 cases of monkeypox have been identified across 37 countries as of 20 June. To date, no deaths have been reported. Infections have been concentrated in Europe, with the UK, Spain, Portugal and Germany accounting for around two-thirds of cases. A high proportion of cases have occurred among men who have sex with men (MSM). Of lab-confirmed cases with a travel history, the majority have recently visited countries in Europe and North America.
The World Health Organisation (WHO) has assessed this outbreak to be of moderate risk level, given that this is the first time many clusters of monkeypox cases have been detected in non-endemic regions. On 23 June, experts from the WHO will meet to decide whether to escalate this to a high-risk level, constituting a Public Health Emergency of International Concern. GlobalData epidemiologists expect that without immediate public health action, the virus will likely continue to spread and may become established in some populations within non-endemic countries.
Monkeypox is a viral zoonotic disease that is endemic to Central and West Africa. Despite a high proportion of cases in this outbreak occurring in MSM, monkeypox is not a sexually transmitted disease. The virus does, however, spread through contact with sores of infected people and contaminated bodily fluids, rendering the MSM group particularly vulnerable to infection. Transmission occurs through close physical contact between people and contact with fomites (ie. contaminated clothing, bedding or surfaces). The CDC has issued new guidance to advocate for increasing testing capacity as cases have escalated in the US in recent weeks.
In most cases, the disease causes mild and self-limiting illness, but the level of risk posed to vulnerable groups such as pregnant women, immunosuppressed individuals and children is unclear. In the past, isolated imported cases of the disease have been detected in non-endemic countries. These patients have been swiftly identified and isolated in specialist healthcare units to prevent further transmission. The critical distinction in this outbreak is that since cases were first detected on 13 May, some countries have observed person-to-person transmission within communities. GlobalData epidemiologists understand that the sudden escalation of case numbers suggests that there may have been undetected transmission of the disease for some time.
Global public health authorities have started to implement disease control measures such as vaccination, advising self-isolation and contact tracing in an attempt to curb the spread of infections. The UK has purchased 20,000 doses of a smallpox vaccine, Imvanex, which is recommended for use both pre-exposure and post-exposure to monkeypox. The vaccine is being offered to close contacts of diagnosed monkeypox cases to reduce the risk of infection and severe illness. In addition, the UK Health Security Agency (UKHSA) has told contacts to self-isolate for 21 days. The US has ordered 500,000 doses of Bavarian Nordic’s smallpox vaccine, which provides up to 85% protection against monkeypox. As was the case during the Covid-19 pandemic, the WHO has urged the governments of high-income countries to share information surrounding vaccine stockpiles and make themselves available to share doses with other countries if required.
The low transmissibility of this virus combined with concerted public health efforts over the coming weeks will hopefully be sufficient to contain the current outbreak. Lessons learned from the Covid-19 pandemic will also help streamline initiatives and underscore the importance of timely case identification, testing and isolation. This outbreak does, however, provide an unprecedented opportunity for the virus to become established outside of Africa. As it stands, no animal reservoir exists outside of Africa. But as a zoonotic disease, monkeypox commonly circulates amongst wildlife species such as rope squirrels, tree squirrels, dormice and other non-human primates. As the outbreak continues, there is the potential for the virus to establish itself in non-African wildlife species. If this were to happen, there is the potential for continued human monkeypox infections on a long-term basis.