UTMB-Galveston scientists tested the blood of people vaccinated with the Pfizer vaccine against the different strains.
With the vaccine using mRNA technology to teach the body how to create antibodies and protect against the virus, doctors wanted to make sure it could withstand any mutations.
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"We took a panel of blood from a human that has been immunized," said Dr. Pei-Yong Shi with the department of biochemistry and molecular biology.
Tests were done on a strain that carries a common mutation and on the South African variant. Researchers found that fewer neutralizing antibodies were produced in the South African variant compared to the other strain tested.
"It's almost three-fold reduction of neutralizing activity," said Shi.
In lab testing, the Moderna vaccine, which also uses mRNA technology, showed reduced neutralizing antibodies against the South African variant too, according to Dr. Hana El Sahly with Baylor College of Medicine.
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"We do know, from the lab, that many of these vaccines are not working as well against the South African variant," she said.
But fewer neutralizing antibodies does not mean the vaccine is less effective. An immune response is still triggered, producing protection above a specific threshold.
The issue is right now, researchers just don't know where that threshold is.
"We do not know what the cut-off (is) that is needed in humans. We do know that they seem to protect against symptomatic disease, against severe disease, but the cut-off is not determined," said El Sahly.
Dr. Shi said, based on what they do know, he believes Pfizer will be effective against the variant.
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"I would call it very modest, and there's a big cushion below that, that will still be very protected," said Shi.
For now, the South African strain isn't prevalent in the U.S. Researchers hope to learn from South Africa and Brazil about how the vaccines are working there, so if the strains become more prevalent, they'll know how to respond.
"All platforms need to examine the ability to reduce severe disease against the South African strain should it emerge here in the United States," said El Sahly.
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