Rapid Response: Incentives Prove Key to Information Gathering

Mpox is a viral disease that commonly involves a painful rash and can result in severe illness and death. So, when cases of mpox began surfacing among people experiencing homelessness in San Francisco, the city public health officials turned quickly to the Centers for Disease Control and Prevention (CDC) for support.

People experiencing homelessness are a highly diverse group, including people who may exchange sex for services, those with substance use issues or other challenges. These types of issues make them vulnerable to infection but often less likely to seek services.

“The question was, are people experiencing homelessness more likely to get mpox, and if so, why,” said Grace Marx, MD, MPH, CDC medical epidemiologist and leader of the serosurvey field team sent to gather data on the outbreak. “City officials were interested in improving vaccine accessibility and understanding whether different strategies were needed to reach this population.”

By agreeing to provide blood samples, survey participants allowed CDC team members ot gather crucial data about the spread of mpox among San Francisco's population of people experiencing homelessness.

Grace Marx, MD, MPH, CDC medical epidemiologist and leader of the serosurvey field team.

A CDC team member holds one of the flyers the team used to recruit participants to the survey.

With mpox cases multiplying, the team had to quickly build trust and acceptance with people experiencing homelessness in San Francisco. Working closely with the city health department, the CDC team connected with more than 30 community-based organizations (CBOs) that had deep ties in the focus communities, a critical first step in the data collection process.

“We had focus group discussions with CBOs that served people experiencing homelessness,” Dr. Marx said. “We wanted them to know what this project was about, and to make sure we were entering these spaces in ways that were respectful and culturally appropriate.”

Dr. Marx and the CDC team then traveled to San Francisco to survey the population of those experiencing homelessness and gather vital information on vaccine access and acceptance. From this initial group of volunteers, the team recruited participants to provide blood samples, which they analyzed to determine rates of previous exposure to the mpox virus, submitting this activity for human subjects and ethical review and receiving approval as a non-research activity. All information collected was anonymous and will be reported in aggregate so that no data can be linked to any individual participant.

In addition, any participant reporting skin lesions consistent with active mpox would be referred for immediate diagnostic testing and treatment. The team also provided participants with information about mpox prevention and how to access mpox vaccination in the city.

We wanted to make sure we were entering these spaces in ways that were respectful and culturally appropriate.

Funded by a private grant from the Robert Wood Johnson Foundation, the CDC Foundation provided free coffee at key survey sites, a small but important tool to draw potential participants. From the same grant, the CDC Foundation provided the team with 400 gift cards to a local grocery store. Each survey participant received a $25 gift card, and those who agreed to give a blood sample received a second card.

“Providing gift cards to a trusted local grocery store was critical, not only for the participants, but to get buy-in from the CBOs that serve this community,” Dr. Marx said. “We were able to show through that gesture that we appreciated the participants’ time and that we really valued them as people.”

A CDC team member conducts the mpox survey with a participant recruited from a San Francisco shelter for those experiencing homelessness.

CDC team members deliver coffee provided by the CDC Foundation which helped to raise awareness about the survey and recruit participants.

Aided by these incentives, demand to participate in data gathering was high. The CDC team exceeded its goal of 250 survey participants, ultimately enrolling 284 participants from 16 field sites that included homeless shelters, soup kitchens, day shelters, service sites and encampments, gathering vital data on the mpox outbreak and vaccine access and acceptability among people accessing services at these locations. In addition, three out of four participants also agreed to give blood, which will yield valuable information on prior mpox exposure among people experiencing homelessness in San Francisco.

After the data is analyzed, the CDC team will share their findings with the San Francisco Department of Public Health to identify clusters of mpox infection and inform high-level public health approaches. If the data reveals mpox vaccination barriers related to homelessness, mental health, addiction, low literacy, risky behavior and language barriers, officials can use that data to better inform mpox prevention and intervention strategies. The data will also be summarized and shared with the participating CBOs, whose work directly impacts the daily lives of those experiencing homelessness.

“People experiencing homelessness can be at higher risk of disease and often also face barriers to access healthcare, so an outbreak like this can be catastrophic,” Dr. Marx said. “Public health efforts need to build on trusting relationships with community partners who serve people at risk. CDC Foundation support for this project helped to make that possible.”

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