The ECDC, the European center that monitors the spread of diseases, has issued an advisory to strengthen control of monkeypox (mpox) and prevent a new spike in infection on the continent. The trickle of cases has continued since the end of April of last year and until April 4 they would have been registered 21,170 affected in 29 countries of the European Union, including six deaths. In the rest of the world, the figure rises to 86,913 confirmed for a year.
Cases skyrocketed last May until reaching their peak in July 2022. Then they began to drop with the vaccination program with very low numbers of new infections since the end of December.
It was an outbreak of a strange infection for the West because to date this variant was only endemic in the African continent. Although no one is free from contracting it, it is transmitted most intensely in adults between the ages of 18 and 40, and mainly among men who have sex with men. Only 1.8% of women and 0.4% of the total number were reported in women and children.
“The number of mpox cases has dropped considerably from the peak in July last year,” says Andrea Ammon, Director of ECDC. “However, there is a risk of an increase in the upcoming spring and summer season due to the festivities and increased holiday travel. Early diagnosis, isolation, partner notification and contact tracing remain keys to effective control of this outbreak and must be supported by appropriate vaccination and behavior change strategies.”
Specifically, the European body calls for close collaboration with civil society and community organizations that serve populations at risk, such as men who have sex with men or unprotected relationships linked to drug use. “This includes liaising with venue owners and organizers of Pride events. Clinicians should also be aware of how to rapidly detect and report smallpox cases to public health authorities to allow for timely and responsive public health interventions.” In spring the main Pride celebrations begin, such as the meeting in Maspalomas in the Canary Islands next May.
No to mass immunization
The European body does not change its position on vaccination. It still does not recommend mass immunization and only in cases of contact with someone infected or preventive in people at high risk of exposure. Preliminary data indicates that, as of March 3, 2023, they have been administered more than 300,000 doses of vaccines in 25 EU countries.
loss of immunity
On the other hand, researchers from the Institute of Tropical Medicine in Antwerp have launched a new hypothesis on the control of this new disease for the West. They believe that the monkeypox outbreak declared in 2022 in several European countries was reduced because herd immunity was achieved.
Cases increased rapidly starting in May 2022, before starting to decline a few months later. The reasons why the outbreak subsided are unclear.
“The rapid increase in cases in May 2022 was likely due to effective viral transmission during sexual contact between individuals with high partner turnover in a geographically widespread and dense sexual network. Insufficient knowledge of the disease, as well as asymptomatic and pre-symptomatic transmission, may have promoted the spread of the disease,” says one of the research leaders, Christophe Van Dijck.
The subsequent decline of the epidemic after July 2022 remains unclear. Possible explanations include increased awareness and behavior change in the population at risk and the acquisition of immunity induced by vaccination or infection.
However, in most countries, the decline in mpox cases had already started before a substantial proportion of the population at risk had been vaccinated.
The group of researchers does not believe that it decreased due to a change in the behavior of the risk population. What they have confirmed is that the first infected generated a ‘network immunity’ that stopped the epidemic.
These investigators are now working on serological and modeling studies to establish whether this hypothesis is true. “In the meantime, we must be aware that future mpox outbreaks may occur if ‘network immunity’ is disrupted, for example by decreased immunity of infected or vaccinated individuals or when peripheral members of the sexual network, previously uninfected, they become more sexually active”, has riveted the researcher.
