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More than 75% of Texans have COVID-19 antibodies, survey says

An estimated three-quarters of Texans have COVID-19 antibodies, either due to natural infection or from a vaccine.

HOUSTON — It's estimated that over 75% of Texans have the antibodies that fight COVID-19, according to a survey done by public health experts with Texas CARES.

The survey also determined that on average, COVID-19 antibody levels peak about 120 days after someone's infected and may return to undetectable levels as early as 275 to 500 days following the virus' infection.

Additionally, experts say those who are not vaccinated and were previously infected with COVID-19 have a lower number of antibodies compared with fully vaccinated survey participants. 

“Texas CARES data revealed to us that fully vaccinated participants showed significantly higher antibody levels than those with a natural infection only,” 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. “This suggests to us that vaccination may provide the highest level of protection, even for those who have had a prior COVID-19 infection and developed antibodies.”

Nearly 4,000 children ages 5 to 19 enrolled in a COVID-19 seroprevalence survey and the data revealed more than 33% who participated have antibodies to the virus, and of those, 50.8% were asymptomatic. Nearly half, 44.9%, of parents reported the pandemic impacted their child’s mental health negatively.

How was the survey done?

Participants were asked to complete a brief survey about their health and were then instructed to visit a participating clinic to have their blood drawn for three antibody tests administered several months apart. This allowed the survey team to measure antibody levels over a longer period of time and understand how long immune protection from natural infection and vaccination may last.

“We are so thankful for all the Texans who volunteered to be in our survey,” said Jennifer Shuford, MD, MPH, Chief State Epidemiologist with DSHS. “We now have a better understanding of antibody levels in a diverse group of Texans with different experiences. Texas CARES participants are helping us understand the dynamics of the pandemic and what we can do to end it. And we’re not done yet.”

Texas CARES is composed of a team of health experts from the University of Texas Health Science Center at Houston (UTHealth Houston) and is funded by the Texas Department of State Health Services (DSHS).

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