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


UTHealth researchers create better way to estimate COVID-19 infections in communities

Published: September 12, 2022

A father puts on a child's mask.

Public health and safety strategies are only as effective as the information that guides them.

Researchers and scientists at UTHealth Houston and the Texas Department of State Health Services (DSHS) developed a more accurate way to estimate the percentage of community members with some level of protection from antibodies developed in response to COVID-19 infection or vaccination. These findings could help shape public pandemic preparedness both now and in the future.

“It is important to know the total percent of people who may have antibodies to COVID-19 in a region,” said Stacia DeSantis, PhD, first author of the study and professor of biostatistics at UTHealth School of Public Health. “This paper helps answer that question by presenting a methodology to estimate the percent of Texans with infection- or vaccine-induced antibodies.”

The article was published today in PLOS ONE, a peer-reviewed scientific journal.

DeSantis and the project team examined data from 88,605 Texans ages 5 and older who volunteered to participate in the Texas Coronavirus Antibody REsponse Survey (CARES). The project began in October 2020 to assess the COVID-19 antibody status over time through questionnaires and blood draws. The project is ongoing and the current study reports findings through October 2021.

Using the combination of infection-induced antibody seroprevalence derived from the Texas CARES project’s data and de-identified population level daily vaccination data obtained from the Texas DSHS, the team created a statistical procedure to estimate total antibody prevalence in a large population over time.

The Texas CARES study provided hard data to confirm a suspicion: From statewide antibody surveillance, the majority of COVID-19 cases were previously unreported or undetected.

By tracking antibodies through blood draws, researchers found that the percentage of infected individuals was three times that of confirmed cases – 35% versus 11.8%, respectively.

“From early on in Texas’ COVID response, and as with many infectious diseases, we expected that there were a large number of unreported and undetected people who experienced infections,” said Stephen Pont, MD, MPH, a co-investigator and medical director with the Texas DSHS. “These findings document those suspicions and will help guide us in our ongoing response to the COVID pandemic.” 

Researchers estimated that during the study’s timeframe, nearly 80% of the Texas population had antibodies from either a COVID-19 infection or receiving a COVID-19 vaccine. Updated projections suggest that that number may now be closer to 98%.

Increasing the accuracy of this data can empower city health officials to be proactive about their public health crisis response “with respect to COVID-19, its future variants or even new pandemics,” DeSantis said.

DeSantis and her fellow researchers look forward to continuing to explore a number of topics in this cohort, including whether having antibodies translates to gaining protection against current or emerging COVID-19 strains, and how long a person keeps their immune response after vaccination.

Learn more about the Texas CARES project at TexasCARESproject.org.

Additional UTHealth Houston authors included Luis G. Leon-Novelo, PhD, Michael D. Swartz, PhD, Ashraf S. Yaseen, PhD, Melissa A. Valerio-Shewmaker, PhD, MPH, Yashar Talebi, MS, Frances A. Brito, MS, Jessica A. Ross, BS, Harold W. Kohl III, PhD, MSPH, Sarah E. Messiah, PhD, MPH, Steve H. Kelder, PhD, MPH, Leqing Wu, PhD, Shiming Zhang, MS, Kimberly A. Aguillard, PhD, Michael O. Gonzalez, MS, Onyinye S. Omega-Njemnob, MBBS, MPH, and Eric Boerwinkle, PhD. Other authors included David Lakey, MD, with The University of Texas System, and Jennifer A. Shuford, MD, MPH, with the Texas Department of State Health Services.