Monkeypox, what evolution for the virus? Short, medium and long term scenarios

Can we hope to end the monkeypox epidemic? For several weeks now, this disease, close to smallpox and which causes fevers and skin rashes in particular, has been drastically decreasing in France and worldwide. How will it evolve in the near or more distant future? The Committee for Monitoring and Anticipating Health Risks (Covars), which took over from the Scientific Council, examined the matter in a notice posted earlier this week. “The current epidemic is declining significantly,” but it “remains difficult” to assess the risks of a rebound or resurgence of monkeypox due to a “large number of unknowns,” he stresses.

Just over 4,100 cases have been registered in France since the beginning of the epidemic. The vast majority of them are found within the community of men in homosexual relationships (MSM), and particularly those who have relationships with multiple partners. Now, the dynamics of the epidemic are declining thanks to prevention within this community and vaccination. Different scenarios emerge in the short and medium term.

According to Covars, in the short term the most serious probability is that of a low noisy circulation of the epidemic. Because if for the moment the trajectory could allow its elimination in France, the gradual easing of behaviors, but also a drop in contact monitoring and insufficient vaccination would not allow us to anticipate a real elimination of the virus. “This is one of the scenarios that we are considering with a high probability in the short term if the community at risk continues to be careful and we continue to strengthen vaccination,” Institut Pasteur model maker Simon Cauchemez warned during a press conference on Monday 28 November . The recovery of the epidemic is not foreseen for the moment, “we cannot exclude it but it is not our preferred scenario in the short term”.

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A very limited epidemic in the general population

In the medium and long term, Covars considers the elimination of mpox (as renamed on November 28 by the WHO) “unlikely” on an international scale and therefore considers it “a risk of resumption of the epidemic”, even “seasonal”, in France, although the epidemic is under control by then. “France is not isolated and what happens there depends heavily on what happens internationally,” recalls Simon Cauchemez. According to him, the prospect of an elimination of the virus in MSM populations is unlikely even if it shows “encouraging” signs abroad, with “a very marked decline for several months”. “The intensity of this reintroduction and the rebounds that may follow will depend on vaccination coverage, immunity in the affected population and the ability of communities at risk to reintroduce behavioral changes in the event of a re-emergence,” the modeler points out.

Judging it “very difficult to maintain risk reduction over time” by modifying behaviors, immunologist and president of Covars, Brigitte Autran, insisted, during the press conference, on a “complete vaccination, as quickly as possible, of the eligible population” . “If we can vaccinate the people most at risk, we can have a huge impact on transmission,” Simon Cauchemez insisted. In France, the target of the vaccine has been estimated at around 300,000 people, and to date 170,000 doses of the vaccine have been distributed (of which 20,000 for the second dose).

Finally, because the dynamics of the epidemic are closely related to the community of men who have sex with men and multiple partners, Covars points out that the potential for infection transmission is low in the general population. As far as we are concerned, the impact of the epidemic remains limited in all the scenarios considered.

Relax the biosecurity rules

The Giunta insists on another axis: monitoring. For this reason, he particularly recommends integrating monkeypox into the monitoring of sexually transmitted infections, even if this is not “the only route of entry for the virus”. By including monkeypox in this surveillance framework, it could be better monitored. “There is a very good network in France, the associations are very connected to this surveillance, the screening centers are effective, the sexual health centres, the hospitals… so there really is an organization that needs to be used “explained Brigitte Autran.

Finally, Covars also recommends a relaxation of biosecurity rules. This virus is currently classified as Microorganisms and Toxins (MOT), a list of pathogens that can be used for terrorist purposes. And this framework very strictly limits its use. “Any laboratory that has this type of pathogen must submit a file to the National Medicines Agency, which details the storage conditions, the conditions of use, which personnel are authorized to handle or be in contact with the virus,” explains Bruno Lina, virologist and member of Covars. A constraint that has forced virology laboratories to adapt to send diagnoses, and which has complicated patient care. “We therefore recommend making this system more flexible, explains Bruno Lina, because in an emergency context, a strategy is needed to be able to support laboratories in order to allow them to make diagnoses”.