Rapid antibody test not as much a problem as its improper use, says doctor

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Metro Manila (CNN Philippines, August 5) — A rapid antibody test still has its merits, Dr. Minguita Padilla of Project ARK said amid calls from health professionals to stop its use in detecting people infected with COVID-19.

For months, several doctors have lobbied against the use of the rapid antibody test due to its questionable reliability, but the calls gained momentum in recent weeks, as the country sees an uptick in COVID-19 infections.

According to Dr. Antonio Dans, this test is only able to detect the antibody and not the virus, and thus can also only find 50 percent of coronavirus cases. The medical community also argued that antibody tests can lead to false negative or false positive results.

“Alam niyo, ang definition namin ng useless test is if it only detects 50 percent of conditions that it is trying to detect,” Dans said in an interview with CNN Philippines on Tuesday. A toss coin, he said, would give just about the same result.

He added that the use of the test as a basis to let employees go back to work might have contributed to the spread of the viral disease.

READ: Use of rapid tests in workplaces may have led to rise of COVID-19 cases, says doctor

But Padilla noted that the tests can still prove helpful when it comes to frequent screening of employees, as well as in contact tracing.

“What we found is that it’s great for zero prevalence, for checking if your workers...like every two weeks, if there’s something happening,” she told CNN Philippines’ The Final Word on Wednesday.

She added that the speed by which an infected person is spotted helps in immediately tracing and isolating contacts. Rapid tests can yield results in 15 minutes, as opposed to a longer turnaround time of 12 to 24 hours for RT-PCR tests.

"You see them early enough, the contacts, and you can actually do your PCR or you can do your quarantine if they have any symptoms," she said.

A big part of the problem, according to Padilla, lies in using the rapid test as a definitive diagnosis tool.

“I remember somebody said that people are symptomatic, and when they test negative for rapid antibody testing, they clear them,” she said. “That is the wrong way to use it. You will really get into trouble, okay? You’ll be releasing people who might be infected.”

Padilla stressed that the conduct of the tests should always be supervised by a medical professional, as she pointed out that the accessibility of the tool likewise poses a problem. There are people buying and using the tests left and right without knowing how to interpret them, she said.

“There’s a wrong way to use it and a right way to use it," she said. "If it’s used in the wrong way for sure it will cause problems.”

In an internal memorandum in May, the Department of Health said rapid antibody tests cannot be used to rule out COVID-19. RT-PCR tests, which remains the gold standard in diagnosing the disease, should still be performed to confirm results of the rapid tests.