There are currently more than 250 cases of monkeypox worldwide – and the trend is rising. This is unusual because the monkeypox virus, which is endemic to West and Central Africa, is actually difficult to transmit between humans. So far, infections have only occurred in Africa itself or in travelers from the endemic area. It is still unclear why there are currently so many outbreaks around the world.

The virologist Gerd Sutter from the Ludwig-Maximilians-Universität Munich researches new vaccines and the global spread of previously unknown pathogens – and is considered one of the leading smallpox virologists in Germany. He answers questions about the current monkeypox outbreaks.

Prof. Sutter, a new virus that jumps from animals to humans, the first cases in Europe. Are we at the beginning of a monkeypox epidemic?

Gerd Sutter: No, I rate the risk of a major epidemic in Germany or Europe as low. The process of the monkeypox virus being imported into Europe by travelers from Africa has been going on for years, insidiously, parallel to an equally insidious outbreak in Nigeria. A few travelers have already brought the pathogen to the USA, Israel, Singapore and Europe in recent years – here mainly to the United Kingdom. What is completely new, however, is that there is now a certain spread in Europe – and of course this has to be monitored.

What are the differences to the Sars-CoV-2 pandemic?

Sutter: There are fundamental differences to the corona pandemic: At that time it was a completely new pathogen and nothing was known about its biology. On the other hand, we already know a lot more about the monkeypox virus, and have known for years: monkeypox viruses belong to the orthopoxvirus group, which we know can infect different hosts.

We also know that transmission occurs through direct contact and particularly through the highly contagious lesions. Transmission by droplets or aerosols plays a subordinate role at most. Transmissions of monkeypox are therefore relatively inefficient compared to infections with Covid-19 or influenza viruses and – with adequate measures for diagnosis and contact determination – usually lead to only short chains of infection.

In addition, there are established detection methods for the virus: The detection of monkeypox viruses is generally possible without any problems for virological specialist institutions in Germany.

And there are vaccines and even an approved drug.

Sutter: The type of virus is also completely different: monkeypox is a DNA virus whose genetic stability differs greatly from RNA viruses such as corona or influenza viruses. Constantly mutating new variants like Sars-CoV-2 – this is not to be expected with monkeypox, which usually has a very stable genome. On the contrary, the at most subtle genetic changes could even help us to understand how the virus was transmitted through Europe.

How can you protect yourself from transmission?

Sutter: Such zoonotic infections with monkeypox in Africa usually occur through direct contact with wild animals – when hunting or preparing venison. Transmission from person to person is possible, but usually requires direct contact with infected people.

The main infectivity resides in the skin lesions, which only develop after the first more general symptoms such as headache, muscle pain and fever. There is a lot of virus in the liquid of these pustules and the crusts that form afterwards. The patients are usually no longer infectious as soon as these crusts have fallen off and the pustules have healed.

What needs to happen to curb the spread of monkeypox, even if its dynamics cannot be compared to Sars-CoV-2?

Sutter: Of course, the authorities – and I have the impression that they are already doing this well – have to understand the contacts and initiate appropriate hygiene and, if necessary, quarantine measures. It can also be recommended to vaccinate contacts. But we certainly don’t need to stockpile large amounts of vaccine.

You conduct your own research and are developing new vaccines, including against smallpox viruses. How well do existing vaccines help?

Sutter: Modern smallpox vaccines approved in Europe, Canada and the USA are based on the vaccinia virus MVA (Modified Vaccinia Virus Ankara), which has been tested for safety and cannot reproduce in mammals and which I have been dealing with since my doctoral thesis. It is a classic vaccine virus that stimulates effective humoral immune responses – i.e. antibodies – and at the same time cellular responses – i.e. T cells.

Cellular immunity is of particular importance in prophylaxis to protect against orthopoxvirus-specific diseases. Due to its clinically proven safety and ability to induce protective virus-specific T-cell responses, the MVA is used – in my current research, we also use the MVA to develop broadly effective vaccines against other emerging viral diseases. The orthopoxvirus serves as a kind of vector that piggybacks on the gene sequences for vaccine antigens from other pathogens – such as Mers or Covid-19 – and introduces them.

Is the classic human smallpox vaccination, from which older people still have a scar on their arm, still effective against monkeypox?

Sutter: You can certainly expect partial protection here. We know from anecdotal evidence that even decades after the WHO’s mass vaccination program against smallpox, a “memory immune response” is still in place. There is clear data that the cellular, the T-cell immunity in particular can still be detected in a virus-specific manner – even if the antibody response in the serum has already disappeared.

However, during the vaccination campaign against human smallpox, the nursing and vaccination staff received a booster shot every three years. It must be said, however, that human smallpox was based on another virus that was much more contagious and more violent in its spread than monkeypox.

How effective is the drug Tecovirimat against monkeypox, which is approved by us?

Sutter: This so-called “small molecule” drug attacks a protein of orthopoxviruses in a highly specific manner, preventing new viruses from being smuggled out of infected cells. It therefore has a really very good effectiveness with good tolerability at the same time. This is known from the first clinical case reports – even if there weren’t many of them, of course. The approval of Tecovirimat was based on a large number of preclinical tests on a wide variety of animal models.

Sars, bird flu, swine flu, Mers, Ebola, Zika, Covid and now monkeypox: are we experiencing an accumulation and acceleration of new diseases and zoonoses in particular – or is that just our impression in the information age?

Sutter: No, that’s actually the case and also our experience in virology. We’ve seen this for 20 years, beginning in 1999 with the sudden conquest of North America by West Nile fever: plane, mosquito, arrival in New York – enough for it to spread across the North American continent within a few years.

Various factors play a role in the accumulation of new viral infections: Firstly, as a result of the growing world population, we have people constantly encroaching into areas where they were not before. The human host system is suddenly accessible to viruses with which humans have never been in contact before.

Nutrition also plays a role: We virologists have been observing these markets in China for years, where it has been proven that new influenza and corona viruses are transmitted from animals to humans.

And, of course, over the past few decades, trade and travel have increased on a globalized scale – allowing a new pathogen to fly from Malaysia to Frankfurt in two days with a passenger. The speed of dissemination has increased dramatically. Another factor is climate change: As a result of temperature developments, virus vectors such as mosquitoes or ticks are penetrating completely new areas.

After the experience with Covid, are medicine and society better equipped to prevent new pandemics?

Sutter: Despite all the damage and misfortune that the Covid 19 pandemic has brought to us: I think it has at least created awareness around the world that such events can actually occur – and that you have to prepare accordingly.

This includes ensuring that health systems are provided with protective clothing and equipped with effective containment strategies, but also that research thinks ahead which pathogens could become dangerous and which vaccines might be needed.

We are certainly also well advised to have the appropriate production facilities for medicines and vaccines available – also locally in Europe. I am myself involved in the “Coalition for Epidemic Preparedness Innovation” initiated and supported by the WHO, a global public-private partnership of companies and important research institutes. This monitors certain “Most Wanted” viruses that are believed to be dangerous under certain circumstances – such as the Crimean-Congo fever or the Mers coronavirus. The monkeypox virus, while now threatening to the public, is not one of them.

Source: Ludwig Maximilian University of Munich

This article was written by Nadja Podbregar

The original of this post “How dangerous is monkeypox? Smallpox researcher explains” comes from scinexx.