New At-Home COVID Tests Not Always Accurate, Doctor Says

November 25, 2020 Updated: November 29, 2020

The free, at-home COVID-19 saliva tests arriving in Orange County before the holidays won’t always accurately detect the virus, says a local infectious disease doctor.

Officials in the Southern California county announced Nov. 17 that it would soon begin offering the free tests to its residents, and encouraged their use prior to holiday get-togethers.

But Dr. Thomas Cesario, former dean of the University of California–Irvine’s medical school, said rapid tests can produce false negatives if taken too soon after becoming infected.

“You could get yourself a negative test today and the test turns positive tomorrow,” Cesario told The Epoch Times.

“Let’s say you have an interaction with someone who’s sick with this. The next day, if you test yourself, it’s probably going to be negative because it takes four or five days for that test to become positive.

“The virus has to grow in you, and until it grows into sufficient numbers, it’s going to be negative.”

Cesario, an infectious disease specialist based in the City of Orange, said it may not take everyone that long to produce a positive test after being infected; it could take more or less time, depending on the individual. He said five days is just an example, and the time for the disease to manifest “may be shorter or longer, depending on the person and their circumstances.”

He likened the process to growing a garden vegetable.

“You could plant carrots, but if you just plant the seed in the ground and you look the next day, there’s not going to be a carrot,” he said. “You’ve got to give it time to grow, and the same is true of a virus, where essentially you have to allow it to grow to sufficient numbers before the test will detect it.”

The accuracy of the tests is also related to how samples are taken, how the agents are stored, and how samples are administered, Cesario said.

“If properly administered, the test can be useful, if the interpretation is made with someone knowledgeable about the assay and the disease,” he said. “They have to make sure the swab is done correctly; it has to be stored correctly, and it has to be timed correctly.”

He noted there are different types of rapid tests; some are based on the detection of the viral protein, while others are based on the detection of the viral genes.

Rapid tests tend to be less accurate than standard tests, he said.

The Orange County Board of Supervisors announced at its Nov. 17 meeting that Orange County would begin offering free COVID-19 saliva tests to county residents. An initial batch of 11,000 polymerase chain reaction (PCR) tests was set aside for residents of Santa Ana and Anaheim, the hardest-hit cities in Orange County.

Beginning next week, all Orange County residents will be entitled to a test. About 500,000 kits will be available by the end of December.

During the meeting, Supervisor Andrew Do encouraged the public to incorporate COVID-19 testing into their holiday plans.

“If you are going to go see your grandparents, or just family in general, two or three days before you go, you want to take a test, the result will be available within 24 hours, then you will know your status going into the gathering,” he said.

Supervisor Doug Chaffee said later that the at-home tests could help alleviate crowds at on-site testing spots.

“These at-home COVID-19 tests will eliminate the need for someone who is feeling sick to go to a testing site or clinic, which in turn means that fewer people are exposed to the virus,” he said in a press release.

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