Multi-country outbreak of monkeypox – first update

Since early May 2022 and since July 7, cases of monkeypox (MPX) have been reported in non-endemic countries. Twenty-six countries in the European Union/European Economic Area (EU/EEA) have reported 4,908 cases, representing 65% of all reported cases globally in 2022.

In the current epidemic in non-endemic countries, most cases have been detected in men between the ages of 18 and 50, and mainly in men who have sex with men (MSM). Particular sexual practices facilitated the transmission of MPX among MSM groups with multiple partners. However, there is also a risk of onward transmission in other population groups. In endemic areas, MPX virus has been detected in a wide range of animal species and the occurrence of zoonotic transmission events cannot be excluded, but there is no documented evidence of human-to-animal transmission or disease. animal to human in the EU. /EEE to date.

Cases in the current outbreak have a spectrum of symptoms and signs that differs from that described in past outbreaks of MPX in endemic countries. In addition, a small number of subclinical or even asymptomatic cases have been described. This result needs to be verified and the public health relevance for transmission needs to be established. In terms of disease severity, in this outbreak, cases presented with mild to moderate symptoms, with only a few hospitalizations reported. The severity of MPX may be higher in young children, pregnant women, and immunocompromised people.

Based on evidence from cases reported in the current outbreak, the likelihood of MPX spreading further in networks of people with multiple sexual partners in the EU/EEA is considered high and the likelihood of spread to among the general population is assessed as very low. The impact of the disease remains low for the majority of cases. The overall risk is therefore assessed as moderate for people with multiple sexual partners (including certain groups of MSM) and low for the general population. The risk of establishment of an enzootic cycle and events of spread to humans is considered low.

Early diagnosis, isolation, effective contact tracing and vaccination strategies are essential to effectively control this outbreak. It is essential to underpin all response measures with risk communication and community engagement efforts. Until recently, MPX was quite rare in the EU/EEA, with only sporadic imported cases being reported. This, coupled with the fact that the clinical presentations of the current outbreak are not typical, makes diagnosis difficult for the average clinician. Activities aimed at increasing the awareness of health care professionals in all specialties should continue, providing information on the range of clinical presentations of currently diagnosed cases, test recommendations and testing procedure, advice on infection prevention and control in primary care, public health measures in place in the country, as well as advice on risk communication and guidance for raising awareness in their communities. In addition, countries should review their diagnostic capacity and increase the availability of tests.

At this stage, mass vaccination against MPX is neither required nor recommended. Unless contact tracing can successfully identify a high proportion of infected contacts, mathematical modeling results indicate that targeted pre-exposure prophylaxis (PrEP) of people at high risk of exposure would be the most effective strategy. to use vaccines to control the epidemic. Therefore, prioritization of groups of MSM at higher risk of exposure, as well as frontline staff at risk of occupational exposure, should be considered when developing vaccination strategies.

Modeling of effective vaccine use indicates that PrEP vaccination would be the most effective strategy when tracing is less effective. The modeling also suggests that vaccinating contacts with post-exposure prophylaxis (PEP) would offer a slightly more efficient approach if there were both higher uptake levels and more efficient tracing (because fewer vaccines would be needed for a relatively larger increase in the probability of epidemic control per vaccinated individual), while the absolute probability of epidemic control with PEP vaccination is even lower than with PrEP vaccination. In settings where higher vaccination coverage is expected, PEP vaccination of close contacts of cases should also be considered, or even ring vaccination. Of these, contacts at high risk of developing serious illness, such as children, pregnant women, and immunocompromised people, should be prioritized.

Targeted national immunization programs should be implemented within a framework of collaborative research and clinical trial protocols with standardized data collection tools for clinical data and outcomes. Targeted health promotion interventions and community engagement are also essential to ensure vaccine uptake and reach those most at risk of exposure. Antivirals for the treatment of MPX should preferably be used in a clinical trial to obtain harmonized safety and efficacy data.

What’s new in this update

This updated rapid risk assessment includes new information on the different clinical pictures of MPX cases in the ongoing outbreak. It includes new insights from a stochastic mathematical model developed in collaboration by ECDC and the European Health Emergency Preparedness and Response Authority (HERA) to assess vaccination strategies as outbreak response measures. It also contains references to all recently produced technical documents on contact tracing, risk communication and community engagement developed in collaboration between ECDC and the Regional Office for Europe of the World Health Organization (WHO) and civil society organizations.

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