Mpox Vaccination for Vulnerable Populations

CE / CME

Protection Beyond Outbreaks: Routine Mpox Vaccination for Vulnerable Populations

Nurses: 1.00 Nursing contact hour

Pharmacists: 1.00 contact hour (0.1 CEUs)

Physicians: maximum of 1.00 AMA PRA Category 1 Credit

Released: July 17, 2024

Expiration: July 16, 2025

Carlos del Rio
Carlos del Rio, MD
Aniruddha (Anu) Hazra
Aniruddha (Anu) Hazra, MD

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Who Is at Highest Risk for Mpox Infection?

Carlos del Rio, MD, FIDSA:
When the current global mpox outbreak began in 2022, HCPs were caught off guard in most regions, including the United States and Europe, in part because most do not have direct experience with poxviruses (as a result of the global eradication of smallpox), but also because the transmission characteristics of the outbreak were quite different from what had been observed in the past for mpox in these regions. As a result, the population experiencing the highest burden of disease also differed.

Mpox 2022-2024 Outbreak: Most Cases Are in Men Who Have Sex With Men

Carlos del Rio, MD, FIDSA:
Although smallpox is a human-specific virus, MPXV primarily infects animals, with humans serving only occasionally as incidental hosts. For example, in a previous outbreak in the United States in 2003, MPXV was spread from prairie dogs to humans and affected people who had been interacting with prairie dogs, including children.1,2 The resulting mpox lesions were primarily on the hands, the site of contact with the animals.

In the current outbreak, the situation is different; cases primarily occurred among adult men who have sex with men, and human-to-human transmission occurred in association with sexual contact. Therefore, when we think about who is at highest risk for mpox in the current outbreak, it is men, and more specifically, men who have sex with men and who have multiple partners. That does not mean that there are no cases in women—there are some as noted previously, but far fewer than in men.

Click for audio from Carlos del Rio, MD, FIDSA.

Mpox Transmission

Carlos del Rio, MD, FIDSA:
Another important point regarding mpox transmission is that, at the beginning of the outbreak when patients started coming to hospitals, there was a lot of concern about the potential for transmission to HCPs. However, with proper infection control procedures, which we had all grown accustomed to during the early years of the COVID-19 pandemic, nosocomial mpox transmission was not a major problem. For the most part, HCPs who developed mpox acquired it in the community, not the healthcare setting.  

Aniruddha Hazra, MD:
Yes, the timing of the mpox outbreak, approximately 2 years into the COVID-19 pandemic, did color our response within healthcare settings. We ended up providing a lot of education to help HCPs understand that orthopoxviruses are very different from coronaviruses in terms of how they are transmitted.

Although there is a low risk of potential transmission from respiratory secretions, MPXV generally requires prolonged face-to-face or intimate physical contact for transmission, which does not occur in healthcare settings to the same degree that it does with household or other close contacts. In the current outbreak, human-to-human transmission has occurred in the context of close, sustained, direct contact with lesions or skin rashes, particularly sexual contact, not casual contact or simply being around someone.

This is an important message because there has been a lot of concern related to casual interactions, for example, people worried that they may contract mpox by attending an outdoor festival. That type of short-term, casual contact has not really resulted in mpox transmission in the current outbreak.

Mpox 2022-2024 Outbreak

Aniruddha Hazra, MD:
An interesting challenge we experienced with the clinical presentation of genital mpox lesions is the potential for confusion with bacterial or viral STIs. There was also considerable cotransmission of mpox with STIs: nearly one third of mpox cases had coinfection with an STI such as syphilis or chlamydia. We have definitely seen that in our clinical practice throughout the course of the outbreak.

This finding makes it important to provide simultaneous comprehensive sexual health services when someone presents with potential mpox to ensure screening for other potential STIs, including HIV.

More than 50% of infections among men who have sex with men in the current outbreak have occurred in people living with HIV, and among that group those with unsuppressed virus—specifically high viral loads and low CD4+ cell counts—carried a substantial proportion of the mortality.3 People with advanced HIV who are not able to access effective antiretroviral therapy are a highly vulnerable population, often profoundly immunocompromised, and were impacted by severe mpox in the current outbreak both in the United States and in other regions of the world. There were also a fair number of new and even acute HIV diagnoses that were made in the context of mpox.