A new study aims to paint a clear picture of the spread of the coronavirus by randomly sampling San Antonio residents from all over the city.

The study San Antonio’s Metropolitan Health District is launching this month will send volunteers door-to-door to collect samples from consenting residents from approximately 50 households in each of San Antonio’s 10 council districts, Anita Kurian, Metro Health’s assistant director, told the Rivard Report.

The goal is to collect samples from 502 households, Kurian said. A sample size that large will help public health officials and the medical community understand how many people in San Antonio who contract the virus show no symptoms, among other valuable data about how the virus spreads.

Because the study involves random sampling, it also can show whether the current testing in Bexar County shows how many people are truly infected. Other similar studies from hospitals, military vessels, and other randomly sampled populations have shown that more than half of those infected with the coronavirus don’t develop a fever, shortness of breath, or any other symptoms.

“While we still don’t have clear evidence of asymptomatic transmission, it’s still possible,” Kurian said. “That can have huge public health implications.”

The study kicks off this week and will continue throughout June, Kurian said. It comes as San Antonio’s total number of cases saw a significant jump Saturday, largely due to a backlog of results from mid-May. The number of cases Sunday night was 2,830, and 74 people in Bexar County have died. Meanwhile, businesses and other facilities across the city continue to reopen and add patrons following loosened restrictions from Texas Gov. Greg Abbott.

“You may be standing next to a person who is infected and doesn’t even know and is transmitting,” Kurian said.

Study participants won’t have their information shared, and only people who consent to having their samples collected will be tested, Kurian said. Ten teams of students and volunteers from UT Health San Antonio and members of the San Antonio Fire Department will do the door-to-door visits.

“We request San Antonians open their doors for us,” Kurian said. “This will be very useful data.”

The sampling itself involves a nasal swab that participating residents will administer themselves. The viral test involves inserting a swab into each nostril, a method Kurian described as “more patient-friendly” than the more common method of inserting a long swab through the nose and into the throat. This sampling method also requires the research volunteers to wear less personal protective equipment than is needed for the deeper swab, Kurian said.

The study is open only to people 18 or older who can legally give consent and have never had any confirmed or suspected COVID-19 diagnosis, Kurian said.

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As part of the sampling, the UT Health volunteer will ask the participant about age, race, ethnicity, occupation, and the number of people in the household, Kurian said. They’ll also ask participants if they have been working from home and how often they leave the house, she said.

The study is one of two ways Metro Health is using mass sampling to better understand how the virus spreads, Dawn Emerick, Metro Health’s director, said in a May 12 briefing. The testing of all nursing home residents and staff and jail inmates and workers also is showing how fast the virus can spread in close settings.

Officials have said that around 75 percent of Bexar County jail inmates who tested positive for the virus were asymptomatic.

Brendan Gibbons

Brendan Gibbons

Brendan Gibbons is the San Antonio Report's environment and energy reporter.