15 per cent death rate, severe lesions reported in patients with mpox alongside advanced HIV: study

During Canada's unprecedented mpox outbreak last summer, Montreal physician Dr. Antoine Cloutier-Blais noticed a concerning trend: Patients co-infected with advanced HIV were reporting lesions across their bodies, and systemic mpox symptoms.

"It was difficult at that time to confirm that suspicion with the data we had," he said.

Now, new research in the Lancet medical journal backs up Cloutier-Blais' early concerns.

The paper, a case study on mpox in individuals with advanced HIV infection, details an aggressive and serious form of the illness formerly known as monkeypox — at times involving skin cell death within lesions, nodules in the lungs, sepsis, and a high rate of death.

This form of mpox appears to be a "very severe skin and mucosal infection with high rates of sepsis and very severe lung complications," said study author Dr. Chloe Orkin, a professor of HIV/AIDS medicine at Queen Mary University of London, in an email to CBC News.

The researchers studied a cohort of nearly 400 patients from various countries, including Canada, who caught mpox while living with HIV and low CD4 cell counts. (CD4 cells are a type of white blood cell that help fight off infections by triggering the immune system to destroy viruses and other pathogens.)

Mortality was roughly 15 per cent in individuals with advanced HIV-related disease, the researchers wrote, while the death rate for people with the most severe immunosuppression doubled to around 30 per cent, Orkin noted.

The staggering findings matter in large part due to high rates of mpox among individuals living with HIV/AIDS, who account for an estimated 38 to 50 per cent of people diagnosed with mpox.

"I think it's an important reminder of how we must not get too complacent even in the face of low case counts, because if the virus encounters a person susceptible to such severe manifestations like people living with advanced HIV, then it can be really devastating," said Dr. Darrell Tan, a clinician-scientist at St. Michael's Hospital in Toronto, whose team contributed data for the Lancet paper.

Calls for more access to mpox vaccines

The takeaways of her findings, Orkin said, are that health-care workers need to be trained on the high mortality rate associated with mpox and HIV-related immunosuppression. 

"Every person with mpox should have an HIV test and every person with HIV and mpox should be tested for immunosuppression," Orkin continued, noting those with advanced HIV infection should also be monitored carefully, given the significantly higher risk of death. 

"Access to mpox vaccines and antiviral treatments are the best way of reducing severity of disease and health authorities should ensure that people living with HIV are prioritized for vaccination and antivirals especially those with immunosuppression," she added.

In Montreal, Cloutier-Blais — who was not involved with the Lancet study — agreed vaccines must be an ongoing priority, and noted, reassuringly, that he now "rarely" encounters patients who haven't had at least one dose of the two-shot mpox vaccine. 

"I have not seen a single [two-dose] failure and rare and mild presentations in patients who had received one dose," he added.

Uptake and access do remain a challenge at a global level, however. 

"We certainly have patients in our care who have low CD4 counts and could be susceptible to these sorts of conditions, and uptake of [second doses] in Ontario have been disappointingly low," Tan, in Toronto, said. 

"Also, there is particular risk in the many parts of the world where access to protective mpox vaccines is non-existent and where the burden of HIV is high."

Demand for second doses in many major cities has dwindled, data shows, while many countries — including those in Africa, and the emerging outbreak hotspot of Mexico — don't have vaccines available at all. 

"It is imperative that vaccines and antivirals become accessible worldwide and more global cooperation is needed here," Orkin said.