麻豆传媒

Though the push is on to make at-home COVID-19 tests much more widely available, patients and their clinicians should be aware of downsides that could diminish their accuracy, experts from the College of American Pathologists .

They cautioned that in addition to being uncomfortable to administer at home and possibly not covered by insurance, such tests may produce inadequate sample material and could be damaged by improper handling, thus producing false results.

It's also unclear whether any or some of the at-home tests -- particularly those detecting viral antigens -- are capable of picking up all of the variants that are increasingly circulating around the country, they said.

"It's very important how it's collected, and also the sensitivity and specificity of the test," said Kalisha Hill, MD, regional chief medical officer for Amita Health St. Joseph Medical Center and St. Mary's Hospital in Kankakee, Illinois. "The most important thing to recognize is that if you do have symptoms and are suspicious that you have COVID, it's very important to see your healthcare provider, and obtain a real-time PCR test for confirmation."

She emphasized that her organization understands the need for various platforms for COVID testing, and that at-home tests are good screening tools "on a one-time basis."

But the "gold standard is still a laboratory performed, real-time PCR test, and that is the most sensitive and most accurate test that we do that is very specific for COVID-19," Hill said.

Carey August, MD, medical director of laboratories for Advocate Illinois Masonic Medical Center, added that if the test requires that the sample be sent to a laboratory, any misstep in the process could lead to a misdiagnosis. "You have to be sure: is it all labeled properly? Is it preserved properly? Did you put it on the heater? Did it sit in the sun? All of these steps can contribute to false negatives, which is what we really do not want."

She emphasized that people using these tests have to realize that inserting a nasopharyngeal swab is uncomfortable, "so people have to know that if they are going to do that particular test at home, they're going to have to do that to themselves."

CAP President Patrick Godbey, MD, who directs the Southeastern Pathology Associates and Southeast Georgia Health System laboratory in Brunswick, noted another challenge. For most of the test kits that require samples be sent to a lab for processing, they must be shipped the same day that samples were collected, which may be inconvenient. These issues worry pathologists, he said.

Will At-Home Tests Detect Variants?

Godbey said most lab-processed tests will detect the variants, and those tests that use a nucleic acid amplification technique apparently do detect known variants. But "there are some antigen tests that we frankly don't know if they will detect the variants," he said. Many of these tests are self-contained, yielding results on the spot.

Each manufacturer of other at-home tests "needs to answer that question on its own." Both the FDA and CAP are asking each manufacturer that question, he said.

The speakers emphasized that as far as what is known today, all COVID-19 tests done in accredited pathology labs have the capability to detect currently circulating variants.

Another issue, Godbey said, are those tests that require individuals to transmit photos of their tests by mobile device, such as a smartphone. "That may be a problem for some of our most vulnerable populations," he said.

The bottom line is that with any test, at-home tests included, "bad data is worse than no data at all," Godbey said.

A person who falsely tests positive will be inconvenienced and perhaps unable to work or participate in activities. But a person who falsely tests negative, he continued, "you go out and see your grandmother and you go to work, thinking wrongly that you do not have the virus and you do."

One looming question the speakers did not address was just how accurate the at-home tests are when used in community settings. In an interview with 麻豆传媒 after the conference, moderator Kisha Mitchell Richards, MD, director of pathology and laboratory at Greenwich Hospital in Connecticut, said that's just not known.

More than 300 COVID-19 diagnostic tests have , she said, with new ones added every week. Among the subset of those intended for at-home use, their companies tout sensitivity rates of 90% to 100%, Mitchell Richards said. But that was in controlled settings. How they function in real life, with other variables such as sample collection or handling, she quickly added, "that's the data we need."

Test Shortages Persist

The speakers also announced showing that close to half of laboratories around the country still have shortages of the supplies they need for COVID testing, and many have resorted to discontinuing testing for other conditions, such as sexually transmitted diseases, because of a lack of pipette tips.

Shortages reported recently are less severe than during earlier months of the pandemic, Godbey said. But it's still unacceptable.

"Almost half of the laboratories surveyed last month are still having problems securing reagents and test kits, 30% of the laboratories are showing shortages of pipette tips, and the number of laboratories still short of SARS-CoV-2 instruments and nasopharyngeal swabs still hovers around 20%," Godbey said.

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