With a new surge of COVID-19 cases sweeping across San Antonio and other regions, data about the transmission of the virus is more crucial than ever. One suspected culprit for the spread is asymptomatic transmission — infected individuals experiencing no symptoms of the virus and unknowingly spreading it to others.

Concerns over this led to randomized, door-to-door testing conducted in June by UT Health San Antonio in collaboration with the San Antonio Metropolitan Health District and the San Antonio Fire Department.

Recommendations to conduct a population-based study of asymptomatic individuals came from the COVID-19 Health Transition Team, which was appointed by San Antonio Mayor Ron Nirenberg and Bexar County Judge Nelson Wolff earlier this year. The team is chaired by Barbara Taylor, MD, MS, associate professor in the Division of Infectious Diseases, and is made up of several other UT Health San Antonio faculty.

Testing data in San Antonio has largely come from those already reporting symptoms, or from those admitted into hospitals for other reasons, with no data coming in from the community at large, said Dr. Taylor.

“This study was really meant to fill that knowledge gap and give us an idea of people in the community infected with COVID-19 without symptoms that could be contributing to transmission in our community,” she said.

Long-standing collaboration with Metro Health made the study possible, especially with the help of student volunteers from UT Health San Antonio.

“It was actually pretty amazing. In six days, they surveyed in total over 500 households,” said Dr. Taylor. The samples came from neighborhoods all across San Antonio, representing each of the city council districts, she said. “Most people accepted the study. There was really great buy-in from the community for the study, which we were really pleased with.”

Each student was paired with a member of the Mobile Integrated Health Care unit, a team made up paramedics from the San Antonio Fire Department. The student-paramedic pairs were tasked with going door-to-door to explain the study, ask questions and offer free COVID-19 testing.

While the paramedics distributed swabs for willing residents to self-test via a nasal swab, the students collected valuable demographic information, as well as information about exposure levels and the precautions residents were or were not taking. Because the study focused on asymptomatic infection, those reporting symptoms were recommended to get tested, but were excluded from the study.

“A lot of people got excited when you said you would give them a free COVID-19 test,” said Robert DelBello, a third-year MD/MPH student who volunteered with the study. “They were really thankful that we were out there trying to collect this data, trying to do something good for the community.”

DelBello noted that not every resident was willing to participate and that it was clear some people were skeptical, wary or misinformed. But for him, the opportunity to educate and converse with people in the community and employ his medical and public health knowledge out in the field was a rewarding experience.

“It was a great way of getting out and doing some public health work. There’s nothing like being thrown into something where you have to be that medical expert or that public health expert,” said DelBello. “It’s just a great way to get out of the house and talk to some real people in the community about COVID-19 and then also help with the study, which is great for me and the school.”

The study was conducted at a particularly pertinent time. Bexar County has seen a large spike in cases in the past weeks. The study was conducted from June 1 to June 7, and the results will provide a unique snapshot into that critical window of time right before the spike and could further determine the risk factors in our community, Dr. Taylor said.

Another important takeaway from the study was the overall success of community involvement. The positive reception from the residents determined that population-based studies and the door-to-door approach is an effective way to conduct research, said Dr. Taylor.

“I think it’s a great model, and if we were to do other community-wide studies, I think it demonstrates that our community is ready for that, and willing to participate in research, which is great news because there are going to be more COVID-19 studies coming.”

Results of the study are not in yet, but the collected samples are being analyzed by teams at UT Health San Antonio.