Following the global resurgence of the mpox virus in 2022, people with HIV were found to be at a disproportionately higher risk of infection and face more severe consequences. Physicians and public health experts encouraged the population to proceed with smallpox vaccination, which is thought to be effective against mpox, but little efficacy data existed regarding its use.
That changed this week. A study published in the Journal of Clinical Infectious Diseases shows that vaccination against mpox is highly protective for people infected with HIV.
“In our cohort, we saw an overall protection efficacy of 84% after one or more vaccinations, meaning that vaccination prevented nearly 9 out of 10 potential cases. “This means that the study’s lead author, Rachel Bender Ignacio, Ph.D., associate professor of medicine, said. At the University of Washington (UW) School of Medicine. “While it is rare to get mpox after receiving both doses, we did not observe any such cases. This means that taking both recommended doses provides very good protection. .”
The study was led by researchers at the Center for AIDS Research (CFAR), a joint program of the University of Washington and Seattle’s Fred Hutch Cancer Center.
Researchers examined data from 19,777 people with HIV who were treated at nine CFAR-affiliated clinic systems across the United States. Data collection took place from January 1, 2022 to May 31, 2023. There were 413 mpox cases in the cohort, translating into an infection rate of 2.2 per 100 person-years. Bender Ignacio pointed out that this is a much higher number than has ever been recorded around the world.
The researchers had access to patient data, including the presence of antiretroviral therapy, detectable viral load, and date of vaccination and mpox diagnosis.
Michalina Montaño, an epidemiologist in Fred Hutch’s Vaccines and Infectious Diseases division, said: “This data will help us understand what outcomes people with HIV experience if they become infected with mpx, and whether vaccines are available for this population.” “This gives us a unique opportunity to answer the question of how effective it is.” She was the paper’s lead author.
When calculating vaccine efficacy for the entire cohort, researchers counted only cases in which patients received at least one dose 14 days or more before diagnosis.
The efficacy of the mpox vaccine in the general population is estimated to range from 65% to 85%. “It’s really encouraging that the proportion of people infected with HIV is at the high end of that range, even though some people have only received one of the two recommended doses,” Montaño said. spoke.
Antiretroviral therapy can restore many of the immune system capacities impaired by HIV and appears to be protective against the most severe symptoms of mpox.
“People who were not taking their medications or who were not taking their medications consistently had the highest risk of being hospitalized with mpox,” she said.
However, the encouraging findings regarding vaccine effectiveness are tempered by a lack of vaccine availability, particularly in Africa, where the incidence of both MPOX and HIV is among the highest in the world.
“What’s even worse about this outbreak, especially this new clade of mpox viruses currently affecting people in Central Africa, is that there is little guarantee of availability of drug treatments or vaccines. ” said Bender Ignacio. “In addition to children, we need to be aware that people with HIV can also become seriously ill from mpox and should be prioritized for vaccination.”
He also noted that, similar to COVID-19 vaccine supplies during the pandemic, access to the mpox vaccine appears to be shifting from resource-poor countries to wealthy Western countries.
Mpox is usually transmitted through kissing, sex, or touching an infected person’s rash or an item that has come into contact with the rash (such as a towel or bedding). In the United States, most mpox cases occur among men who have sex with men.
“In areas where people are highly immunosuppressed, either due to HIV or malnutrition, or where their immune systems are untrained, such as young children in Central Africa, or where many people live in close quarters. “The risk of serious illness from M.P.O.X. is much higher in poorer areas,” said co-author Dr. Adrian Shapiro, an infectious disease specialist and global health researcher in Medicine, Wisconsin.
“It should be reassuring that the data in this paper shows that vaccines are incredibly effective, which is why we are working hard to get these highly effective vaccines to those who need them most. “You can put a lot of emphasis on that,” she added.
This study was supported by funding from the National Institute of Allergy and Infectious Diseases (R24 AI067039, P30 AI027757). The authors’ conflict of interest statement is available in the paper.
