Why the latest MPOX outbreak has health experts concerned

The escalating MPOX outbreak has some health experts concerned that the latest strain of the virus could spread faster and be more deadly than an outbreak in early 2022.

Last week, the World Health Organization declared MPOX a global public health emergency following the spread of an outbreak in the Democratic Republic of Congo (DRC) to neighbouring countries.

Since the start of the new outbreak, cases have been identified in countries where MPOS is not endemic, such as Sweden, Pakistan and Thailand, although it is unclear which strain has not been identified in some of these countries.

Mpox is a viral infection which is spread through close contact and causes flu-like symptoms and pus-filled lesions. Although it is usually mild, it can be fatal.

WHO Europe director Dr Hans Kluge said on Tuesday the outbreak was “not the new Covid” and could be stopped through international cooperation.

But health experts have warned that “many unknowns” surrounding the latest outbreak – and in particular a new sub-variant – could make it more difficult to contain.

“Clade 1b is a recent development and there are many unknowns that need to be addressed,” said Trudie Lang, professor of global health research and director of the Global Health Network at the University of Oxford.

“Emerging evidence shows differences in transmission and symptoms; for example, transmission is more common from person to person and from mother to baby during pregnancy,” she said.

There are two main types of MPOX, called clades, with the latest outbreak identified as clade 1. Compared to the 2022 strain, clade 2, the current strain, appears to spread more easily and has a higher mortality rate.

A newly identified subvariant of clade 1b was found to be particularly prevalent among young people and appears to be spreading through sexual networks, said Jonas Albarnaz, a poxvirus researcher at the Pirbright Institute.

He noted, however, that more data were needed to understand the dynamics of its transmission and to “inform control strategies.”

Clade 1 is already known to cause more severe forms of the disease in young children, pregnant women and people with compromised immune systems. This has accelerated the epidemic in countries where certain diseases are more prevalent and health systems are weaker.

“As MPOX disease is more severe in immunocompromised people, it is also concerning that the current outbreak is occurring in a region where HIV prevalence is relatively high but access to antiretroviral drugs is limited,” said Brian Ferguson, associate professor of immunology at the University of Cambridge.

Ongoing conflicts in parts of Africa – such as the DRC, where large numbers of displaced people have been relocated to refugee camps – have also worsened hygiene conditions and accelerated the spread of the virus.

So far this year, more than 15,000 cases and at least 537 deaths have been reported due to the outbreak in the DRC, according to the WHO, and more cases have been reported elsewhere.

Ferguson said more cases are likely to be identified in the coming days and weeks, given the lack of control measures to prevent the spread from one country to another. He also said lessons had not been learned from the previous outbreak, which was declared a public health emergency in July 2022 before that designation was removed in May 2023.

“The lack of activity in the meantime has given rise to what could become a new global epidemic. Efforts should have been redoubled to produce and distribute vaccines to affected areas, but that has not been the case,” he said.

It comes after the company submitted data to the European medicines regulator on Friday to expand the use of its MPOX vaccine to adolescents.

CEO Paul Chaplin told CNBC at the time that getting approval for 12- to 17-year-olds would be crucial to combating the outbreak of the latest strain of the virus.

“More than 70% of cases in Africa are currently in people under 18 years of age, so it will be critical that our vaccine can be used in this younger age group,” he said.