Mpox poses serious risk to people with advance HIV

New research shows that people with HIV who have a CD4 count less than 200 are at significant risk of serious illness and death from mpox. 

What is this research about? 

People with advanced HIV (CD4 counts below 350) who got mpox (formerly called monkeypox) between May 2022 and January 2023.  

Why is this research important? 

Last year, there was a global mpox outbreak in which 110 countries reported cases, mainly among gay men and other men who have sex with men. The outbreak was centred in Europe, the UK, North America and Latin America. Between 38-50% of people who got mpox during the outbreak also had HIV. 

Mpox is now under control in high-income countries. But it is still an issue in some low- and middle-income countries. This is particularly the case in west and central Africa where mpox has been around for years and affects a wider range of people.  

Until now, research about HIV and mpox has focused on people who are on antiretroviral treatment (ART) and have undetectable viral loads and good CD4 counts. This shows that people on effective ART are no more at risk of getting severely ill or dying from mpox as people without HIV. But data on the effects of mpox on people with advanced HIV has been limited. 

What did they find out? 

The study included 382 people with advanced HIV and mpox. Most were cisgender men in Latin America and the USA (73%) and Europe (26%). Just 2% were in Africa (Nigeria).  

People’s median CD4 cell count was 211 (200 is the level that AIDS is diagnosed). Most people (91%) were already diagnosed with HIV when they got mpox, and 65% of people with diagnosed HIV were on ART.  

The lower people’s CD4 counts, the more severe the mpox symptoms they were likely to get. For example, 54% of people with CD4 counts below 100 had severe skin lesions, compared to 7% of people with CD4 counts above 300.  

Mpox caused lung disease for 29% of people with CD4 counts below 100, but this condition did not affect anyone with a CD4 count above 300. A life-threatening blood infection called sepsis affected 44% of people with CD4 counts below 100, compared to 9% of people with CD4 counts above 300. 

Just under one-third (28%) of people were hospitalised, of whom 25% died. No one with a CD4 count above 200 died. Among people with CD4 counts below 200, the death rate was 15%. Among people with CD4 counts below 100 it was 27%. 

Only 16% of people got mpox treatment (the antiviral tecovirimat) as it is only widely available in Europe and the USA.  

A total of 85 people started or restarted ART. Of these, 25% had something called immune reconstitution inflammatory syndrome (IRIS). This is when people become unwell because their immune system is getting stronger and fighting previously undetected illness in the body. In this study, 57% of people who developed IRIS died.  

What does this mean for HIV services? 

It shows that people with mpox should be tested for HIV, and those with a CD4 count below 200 should be prioritised for mpox treatment and vaccination. But many countries are struggling to access both mpox vaccines and tecovirimat. These findings can be used to advocate that this is an urgent issue that needs to rise up the health agenda. 

The team behind the study are calling for mpox to be classified as an AIDS-defining opportunistic infection. In some countries, having an AIDS diagnosis means people can get extra services and financial support, which makes this something worth advocating for. 

The findings also show how important it is that people who are at a high risk of HIV get tested and, if they are diagnosed with HIV, start ART immediately.  

But if people are diagnosed with advanced HIV and also have mpox, whether they should start ART immediately needs to be carefully considered. Doctors need to be aware of the symptoms of IRIS and be able to weigh up the risks of starting ART compared to the chances of getting mpox under control first – and this will depend on access to mpox treatment and vaccines.