Statement from Society of Virology (GfV) e.V. on the current Mpox situation

Statement from Society of Virology (GfV) e.V. on the current Mpox situation

Mpox (formerly monkeypox) is a re-emerging, zoonotic and potentially life-threatening viral disease caused by the monkeypox virus. Monkeypox virus is a smallpox virus endemic to Central and West Africa. In May 2022, human Mpox diseases caused by the monkeypox virus clade IIb occurred for the first time worldwide in over 100 countries. In addition, Mpox cases in humans in the Democratic Republic of Congo (DRC) caused by the new monkeypox virus clade Ib have been on the rise since the beginning of 2023. A new feature of these monkeypox viruses, clade Ib and clade IIb, is the sustained and efficient human-to-human transmission without the need for an animal virus reservoir. More than 106,000 human cases of Mpox and 234 associated deaths have been reported worldwide. Interestingly, the clinical presentation of clade IIb infections is characterized by a mild course with a localized rash on certain parts of the body and a low mortality rate. In contrast, infections with the monkeypox virus clade Ib in the Democratic Republic of the Congo are characterized by more severe and also fatal courses of the disease with a generalized skin rash. It is not yet understood why the monkeypox virus currently spreads so efficiently from person to person. However, there are indications that the monkeypox viruses have acquired some mutations in their genetic material through circulation in the human population, which may give them an advantage in human-to-human transmission. The human enzyme APOBEC3 appears to play a crucial role in this.

After an incubation period of 5-21 days, non-specific symptoms with general malaise, fever, headache and fatigue appear first. This is soon followed by the characteristic generalized skin rash, which is characterized by blisters and pustules and mainly appears on the face, trunk and limbs. However, the skin manifestation can also be limited to a specific area of the body, such as the anogenital region or the oral mucosa. At this stage, the patient is highly contagious due to the large amount of infectious monkeypox virus in the lesions. The monkeypox virus is transmitted via pustules and crusts as well as saliva and other bodily secretions, mainly through close physical contact with infected persons.

The clinical symptoms with the characteristic skin rash already suggest an infection with the monkeypox virus. Monkeypox viruses can be reliably detected by PCR after taking secretions from the smallpox lesions using a dry swab or after direct sampling of crusts or skin particles. Further PCR diagnostics also allow differentiation between the various monkeypox virus variants (clade Ia and Ib, as well as clade IIa and IIb).

Due to the high cross-reactivity to other smallpox viruses, the smallpox vaccination with vaccinia virus carried out in the past also protects against infections with the monkeypox virus. Approved smallpox vaccines based on the modified vaccinia virus Ankara (MVA) are also approved against Mpox, such as IMVANEX in Germany. As an improved vaccine against smallpox in humans, MVA was already tested as safe on more than 100,000 people in Germany between 1964 and 1970. After MVA vaccination, robust and long-lasting smallpox virus-specific immune responses were demonstrated in humans. MVA was also used successfully and on a large scale in Germany during the global Mpox epidemic in 2022. It is noteworthy that MVA can prevent severe disease progression or even the disease itself in unvaccinated people after exposure to monkeypox viruses as part of a post-exposure vaccination. MVA vaccinations are approved from the age of 18. To protect against infection with monkeypox viruses, the Standing Committee on Vaccination (STIKO) recommends vaccination after contact with Mpox patients for post-exposure prophylaxis and for prophylaxis when indicated. Two subcutaneous vaccine doses are administered at least 28 days apart. For people who have already been vaccinated against human smallpox in the past, a single dose of vaccine may be sufficient. MVA vaccinations can also be administered to immunocompromised persons and persons with atopic dermatitis. Symptomatic treatment of Mpox involves local treatment of the skin lesions with anti-inflammatory and pain-relieving ointments. In addition, there are antiviral substances that are approved for use in humans for monkeypox virus infections. These include Tecovirimat, a specific smallpox virus inhibitor that inhibits the spread of the virus and whose efficacy against monkeypox viruses has been confirmed in various studies. Studies are currently underway to evaluate its efficacy against the various monkeypox virus variants in clinical trials. Other antiviral agents against monkeypox viruses are brincidofovir and cidofovir, which can inhibit virus replication.

By Prof. Dr. Ingo Drexler and Prof. Dr. Asisa Volz (Chairwoman of the Commission on Zoonoses and Viral Infections of Animals) in consultation with the GfV Executive Board

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