AUSTIN, Texas - An ongoing University of Texas study aims to understand the human antibody response to COVID-19.
The Texas CARES (Coronavirus Antibody Response Survey) is being conducted by researchers at the UT Health Science Center at Houston. Currently, more than 88,000 people of all ages have been enrolled.
The overall goal is to look at the potential differences between vaccine-induced antibodies and antibodies from prior infection, which can be identified through different testing methods.
"Unlike natural infection…which targets a number of different proteins, this antibody targeting the spike protein was kind of unique to the vaccine," said Dr. Kristin Mondy, M.D., chief of the Infectious Diseases Division at UT Austin’s Dell Medical School.
As of October 3, findings from the study show that about three-quarters of the Texas population are believed to have COVID-19 antibodies, whether by prior infection or vaccination. More than a third of children have antibodies to the virus.
Antibody levels appear to peak about 120 days after infection and then decrease, but still remain detectable after up to more than a year. Unvaccinated individuals with a previous infection appear to have lower antibodies to the spike protein compared to fully vaccinated individuals.
"I just had my blood drawn for the second time and I got the results back, and it showed that the natural immunity I have from having COVID is going down, but the antibodies I had from the vaccination from back in April have stayed pretty much the same," said David Squires, who is participating in the Texas CARES study.
However, Dr. Mondy said predicting immune response is more complicated than looking at antibody levels.
"People will respond to a vaccination differently, and people respond to natural infection differently," said Dr. Mondy. "You can’t use it quantitatively - like how high is the number on that blood test you did - because we don’t have enough data to correlate that with immunity to reinfection."
Dr. Mondy said the best way to predict an immune response is by taking - for example - a vaccinated person’s plasma and infecting with the virus. The labor-intensive method has been utilized by specialized labs to test how well the current vaccines hold up against the new Omicron variant.
Ultimately, when it comes to the effectiveness or longevity of vaccines or naturally acquired immunity, Dr. Mondy said there are still many unknowns.
"If you’ve had two doses of the vaccine or COVID naturally, it looks like you do have a reduction in incidents of symptomatic disease for probably up to six months," said Dr. Mondy. "And that would correspond with when they recommend boosters."
To view the Texas CARES Dashboard, click here.