As this mpox outbreak is evolving, stay tuned for future updates on this important news.
This week’s declaration by Africa CDC that the ongoing mpox outbreak is a Public Health Emergency of Continental Security and yesterday’s announcement by the World Health Organization that the disease was a global health emergency heightened the situation and raised concerns around the world.
Making the Distinction Between Clade I and Clade II
Mpox has 2 distinct genetic clades (subtypes of MPXV), I and II, which are endemic to central and west Africa, respectively. Clade I mpox has previously been observed to be more transmissible and to cause a higher proportion of severe infections than clade II. The ongoing global mpox outbreak that began in 2022 is caused by clade II, which is not as deadly as its clade I counterpart, as WHO noted in its May 2024 strategic framework.1
It is very important to make the distinction that the ongoing outbreak in Africa specifically around the Democratic Republic of Congo is related to clade I. Thus far in the US, the American CDC says there are no cases of clade I in the country, and that the risk to people in the United States is low.2
“I think certainly clade I is causing concern in Africa, but let us make sure that we remember that clade II really continues to circulate at low levels in the US, and that’s really especially among unvaccinated, high-risk prioritized communities, and it’s often really concerning for people with uncontrolled HIV that aren’t at suppressed viral loads,” said Scott Bertani, the director of Advocacy of the National Coalition for LGBTQ Health.
Clade II was first seen in the US back in 2003, but has been mostly dormant up until a couple of years ago. This form of mpox has been circulating in the US, and 2 years ago, US Health Secretary Xavier Becerra declared mpox a National Public Health Emergency. This allowed for mobilization of funding and resources to address the virus.
In the US, and since May 2022, there have been 32,063 confirmed cases of mpox and 58 deaths in the US. However, the CDC has stopped collecting the case loads, so Bertani recommends contacting the local health departments to find out local transmission rates.3
Mpox in the US has largely affected certain communities, explains Bertani. “It’s particularly among men who have sex with men, and gay and bisexual men, but as well as transgender and nonbinary individuals.”
Prevention and Treatment
In terms of prevention, Bertani says vaccination is paramount. The MVA-BN (Jynneos) vaccine is FDA approved and widely available in the US. “If you have your first and your second dose, we’re actually seeing less than 1% breakthrough infections of individuals who have been dually vaccinated,” Bertani said.
On the treatment side, there are no FDA-approved therapies; however, clinicians may be able to prescribe antivirals such as cidofovir or tecovirimat. These therapies are approved to treat other viral infections such as smallpox. More often, mpox is a self-resolving disease for patients and typically lasts 2 to 4 weeks.4
Is Clade I Coming to the US?
Yesterday, WHO identified the various forms of mpox transmission including, direct contact with infected animals or humans, spreading via bodily fluids, respiratory droplets, or contaminated objects.
Respiratory droplets means it is airborne. And at the time of this report, Sweden had just announced a case of the Clade I of mpox —the first to be recorded outside of Africa—from a person who had recently traveled to Africa. Public health officials caution there is still a lot to learn about clade I and its transmissibility.
