Colorized transmission electron micrograph of mpox virus particles (red) found inside an infected cell (blue), grown in the laboratory.
Bsip | Universal Images Group | Getty Images
A growing outbreak of mpox is causing alarm among some health experts, who warn that the latest strain of the virus could spread more quickly 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 the Congo (DRC) to neighboring countries.
Since the new outbreak, cases have been identified in countries where mpox is not endemic, such as Sweden, Pakistan and Thailand, although it is unclear which strain has not been identified in some of these nations.
Mpox is a viral infection which spreads through close contact and causes flu-like symptoms and pus-filled lesions. Although it is usually mild, it can be fatal.
WHO director for Europe Dr Hans Kluge said on Tuesday that the outbreak is “not the new Covid” and can be stopped with international cooperation.
But health experts have warned of “many unknowns” surrounding the latest outbreak – and in particular a new sub-variant – that could make it difficult to contain.
“Clade 1b has only recently emerged and there are many unknowns that need to be addressed,” said Trudie Lang, a professor of global health research and director of the Global Health Network at the University of Oxford.
“There is growing evidence of differences in transmission and symptoms, for example, the virus is more commonly transmitted from person to person and from mothers to their babies during pregnancy,” she said.
Broadly speaking, there are two types of MPOX, known as clades, and the latest outbreak was 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 clade 1b subvariant has been 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.
However, he noted that more data is needed to understand its transmission dynamics and “inform control strategies.”
Most vulnerable countries
Clade 1 is already known to cause more severe disease in young children, pregnant women and immunocompromised people, which has accelerated the outbreak in countries where certain health conditions are more common and those with weaker health care systems.
“Given that mpox disease is more severe in immunocompromised individuals, 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 poor,” said Brian Ferguson, associate professor of immunology at the University of Cambridge.
Ongoing conflicts in parts of Africa – such as the Democratic Republic of the Congo, where large numbers of displaced people have been relocated to refugee camps – have also worsened health conditions and accelerated the spread.
So far this year, more than 15,000 cases and at least 537 deaths have been reported from the outbreak in the Democratic Republic of Congo, according to the WHO, with more cases reported elsewhere.
Ferguson said more cases were likely to be identified in the coming days and weeks given the lack of controls to prevent 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 the designation was removed in May 2023.
“The lack of activity in the interim has led to what could now become a new global outbreak. Greater efforts should have been made to produce and distribute vaccines to affected areas, but this has not happened,” he said.
Vaccines for the youngest
This comes after the company submitted data to the European Union's drug regulator on Friday to expand the use of its mpox vaccine for adolescents.
CEO Paul Chaplin told CNBC at the time that getting approval for 12- to 17-year-olds would be crucial to addressing the outbreak of the latest strain of the virus.
“Currently, more than 70% of cases in Africa are 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.
