The Texas Coronavirus Antibody REsponse Survey (CARES) seeks to understand the human antibody response to SARS-CoV-2, the virus that causes COVID-19.


Texas CARES: Over 20% of Texans may have COVID-19 antibodies

Published: March 15, 2021

A gloved hand holds vials from a blood test

Four months after launching the nation’s largest COVID-19 serological testing assessment, Texas CARES, researchers at The University of Texas Health Science Center at Houston (UTHealth) and the Texas Department of State Health Services (DSHS) have compiled preliminary data estimating that 14% to 24% of Texans have COVID-19 antibodies.

The presence of antibodies indicates a past infection and presumably some degree of immune protection against SARS-CoV-2, the virus that causes COVID-19 illness. “Knowing the number of people with antibodies who participated in Texas CARES, along with the number of vaccine recipients permits public health officials to gauge Texas’s progression toward herd immunity,” said Eric Boerwinkle, PhD, dean, M. David Low Chair in Public Health, and Kozmetsky Family Chair in Human Genetics at UTHealth School of Public Health.

The team from UTHealth consists of public health experts across UTHealth School of Public Health’s six campuses in Houston, Dallas, Austin, San Antonio, Brownsville, and El Paso.

The assessment data is broken into two groups: a population sample that provides a diverse snapshot of seroprevalence across Texas including children, and a patient sample that is measuring unidentified blood samples that are destined for destruction at participating clinics across the state. Differences in age distribution, comorbidities, and enrollment motivation between the two samples may account for the differences in the seroprevalence data.

The team estimates that the level of COVID-19 antibodies across the state of Texas ranges from 24% in 6,998 population samples to 14% in 78,517 patient samples. Data from the population sample estimates that 27% of Hispanic Texans have COVID-19 antibodies, and for Texans younger than 19 years of age, 29% have antibodies.

“The Texas CARES study is cutting-edge science that will provide valuable information to enable Texas to formulate public health strategies that will ultimately defeat the pandemic,” said John Hellerstedt, MD, commissioner of the Texas Department of State Health Services.

Both Boerwinkle and Hellerstedt stressed that although the seroprevalence results are promising, it is important that all Texans continue to practice good public health practices including social distancing, mask wearing, and handwashing. In addition, when given the chance, Texans should sign up for the COVID-19 vaccine.

The assessment is still enrolling participants, regardless of prior COVID-19 infection or vaccination. Texans ages 5-80 can participate in Texas CARES by registering at TexasCARESProject.org or contacting the team at TexasCARES@uth.tmc.edu or 713-500-9441.

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