FDA releases revised false positive guidelines for blood banks

South Texas Blood & Tissue Center notifying donors for retesting

SAN ANTONIO – Using revised FDA guidelines, the South Texas Blood and Tissue Center reports it is notifying about 200 donors for retesting after they initially had false positive results.

“The FDA revised its guidelines to allow blood centers to do additional work with these donors – for example, by doing additional rounds of retesting – which can eliminate false positive test results and qualify them to give blood again,” said Samantha Gomez Ngamsuntikul, the center’s associate medical director.

Before the FDA revised the guidelines, she said a single false positive would require retesting, and two false positives meant they would be permanently “deferred” or were no longer allowed to donate blood.

Doing so, she said, meant losing a very small, but vital number of potential donors at a time when the supply is critically short.

“Around 200 out of 75,000, that’s even less than 1%,” she said were false positives found especially in those who’d been recently vaccinated.

“They can be positive for a number of infectious diseases, so we do additional testing,” Gomez Ngamsuntikul said.

She said if they still test positive, for example syphilis or hepatitis, a final test is done to confirm the results.

However, she said the majority are found to be negative.

At that point, Gomez Ngamsuntikul said, “We allow that donor to come back and retest again or to donate with additional testing.”

She said the re-entry times can vary, but retesting or additional testing will be done, even if apparently negative, because “maybe they will later be a true positive, and it’s an evolving positive.”

Or she said, perhaps their antibodies levels remain high after for getting flu or COVID-19.

She said under the revised guidelines, “If you are one of those really rare people that gets a false positive result, we’ll work with you on that.”

As of Monday, the South Texas Blood and Tissue Center reported only a two-day of blood remained, and only a day and half supply of high demand Type-O blood.

Donations can be made by clicking here or calling 210-731-5590, but walk-ins will be accepted as space allows.

Also on KSAT.com:

About the Authors:

Jessie Degollado has been with KSAT since 1984. She is a general assignments reporter who covers a wide variety of stories. Raised in Laredo and as an anchor/reporter at KRGV in the Rio Grande Valley, Jessie is especially familiar with border and immigration issues. In 2007, Jessie also was inducted into the San Antonio Women's Hall of Fame.

William Caldera has been at KSAT since 2003. He covers a wide range of stories including breaking news, weather, general assignments and sports.