March 16, 2021 -- At-home testing for COVID-19 features great convenience, but pathology experts caution that false positives, false negatives, out-of-pocket costs, and the potential for inadequate sampling from people swabbing their own noses or mouths could compromise results.
Experts agree that COVID-19 testing has had its challenges and has evolved over the past year.
"It's a very, very significant day," Kisha Mitchell Richards, MD, director of pathology and laboratory at Greenwich Hospital, in Greenwich, CT, said during a March 11 webinar on COVID-19. The webinar was sponsored by the College of American Pathologists (CAP).
"It's 1 year ago today that the World Health Organization declared COVID-19 a pandemic and basically set in stone a year that was going to change our lives probably forever," Richards said.
During that time, "PCR testing" became more of a household term, community and preoperative testing changed and expanded, and the FDA granted emergency use authorization for more at-home tests. Among them is the first molecular-based at-home test, which was authorized last week.
However, the number and nuances of COVID-19 tests have left some people with questions.
"People are still having difficulty understanding the tests. This may be due to the shift in focus to the vaccines and/or being overwhelmed and confused by the amount of information available," said Patrick Godbey, MD, , laboratory director of Southeastern Pathology Associates and Southeast Georgia Health System, in Brunswick, GA.
"Nearly 2 out of 3 Americans, 67%, would like more information about the accuracy of COVID-19 tests," he said during the webinar.
Screen but Verify
At-home tests are good screening tools, said Kalisha Hill, MD, regional chief medical officer at Amita Health St. Joseph Medical Center, Joliet, IL. However, she said laboratory-performed real-time PCR testing remains the most sensitive and accurate test for the coronavirus.
"The most important thing to recognize is that if you do have symptoms or are suspicious that you have COVID-19, it's very important to see your health care provider and obtain a real-time PCR test for confirmation," Hill said.
Godbey shared an adage that applies to all forms of testing for COVID-19, including at-home tests: "Bad data is worse than no data at all."
False positive and false negative results are not unique to at-home testing, but they remain a concern.
"If you think you're positive and you're not, that changes everything you do," Godbey said. "False negatives are even worse. You see your grandmother, and go to the office, thinking you don't have the virus, and you do."
Self-Swabbing Less Certain
"Like the testing we do in the hospital and in our laboratories, we have to make sure that the public doing this at home understands the importance of proper collection and proper storage," Carey August, MD, president of the board of directors of the College of American Pathologists Foundation, said during the webinar. "Did it sit in the sun? Did you put it on the heater? All of these steps can contribute to false negatives, which is what we really do not want."
Proper collection and handling of samples is critical to accuracy, August, medical director of laboratories at Advocate Illinois Masonic Medical Center in Chicago, said
"Sometimes people refer to pathologists as being a little persnickety about sample collection and sample preservation, but there's a reason for that, and it's the health of the people we serve," she said.
It remains important to distinguish between the two main types of at-home tests, and they both can have problems. In one type of at-home test, consumers swab and send a sample to a laboratory the same day. Labelling and handling can make a difference, August said.
With the other type of test, the kits produce results at home, but to report findings often requires a smartphone or laptop. Some cases could go unreported, and not everyone has access to a smartphone or digital device, Godbey said.
"This may be a problem in vulnerable populations," he added.
The out-of-pocket cost associated with at-home COVID-19 tests can also be a factor, particularly for people who test themselves repeatedly, Richards said.
"On a purely practical level, cost can also become an issue," she added. "Some of these tests, unlike the hospital-based or other more commercial laboratory tests, may not be covered by insurance."
Viability for Virus Variants
Current laboratory tests are sensitive to the COVID-19 variants of concern, such as those from the United Kingdom, South Africa, or Brazil, the panelists agreed. At-home tests, likewise, appear to detect these variants, although CAP and the FDA have requested additional information from manufacturers to confirm their sensitivity and specificity.
"It looks like they will detect the variants, but that's a question that each manufacturer needs to answer," Godbey said.
"Some people may be sicker if they have one particular variant than another," Hill said, and that's a concern. "So it's very important that our testing platforms are able to detect all of these variants."
Hill reiterated, especially in light of variants, that people who test positive with an at-home should have their results verified with a PCR test. She recommended getting this confirmation as soon as possible "so that you can be treated earlier, just in case you do have a variant that may make you sicker than the original virus strain."
Richards said she did not want to diminish the convenience of at-home testing, but "there are other factors to consider." For example, if a person who suspects they have COVID-19 undergoes testing at a laboratory and has a question or concern, "you can call my laboratory and you can speak to me.
"I can talk to you about your test. I can retest you. We're accessible," she added.