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At-home COVID-19 diagnostic tests: Answering important questions

COVID-19 Tests

Clarissa Chan, PharmD

At-home COVID-19 diagnostic test.

Home-based rapid diagnostic testing is integral in the fight against COVID-19.

“Home tests can be an important tool for preventing the spread of COVID-19 and keeping schools and businesses open,” said Michael E. Klepser, PharmD, FCCP, FIDP, a professor of pharmacy practice at Ferris State University College of Pharmacy in Michigan. Klepser helped author a November 2021 systematic review published in JAPhA comparing at-home diagnostic tests for COVID-19 that have been granted an EUA.

The following questions highlight key points about these tests, as addressed by Klepser.

Which at-home tests have been granted EUAs?

According to the review in JAPhA, 9 COVID-19 home tests—including 3 molecular tests and 6 antigen tests—have been granted EUAs from FDA. They were all found to perform satisfactorily in comparison to gold-standard laboratory real-time reverse-transcription polymerase chain reaction tests.

The molecular tests include Lucira COVID-19 all-in-one test kit, Lucira CHECK-IT COVID-19 test kit, and Cue COVID-19 test for at-home and OTC use.

The antigen tests include BinaxNOW COVID-19 Ag card home test, BinaxNOW COVID-19 antigen self-test, BinaxNOW COVID-19 Ag card 2 home test; QuickVue at-home COVID-19 test, QuickVue at-home OTC COVID-19 test, and Ellume COVID-19 home test.

What are positive and negative predictive values?

Rather than focusing on sensitivity and specificity, pharmacists should understand positive and negative predictive value (PPV and NPV) and how these values influence the interpretation of results. For any given test, if it is being used in an asymptomatic patient (low probability of disease), a positive test is more likely to be a false positive (low PPV). In this case, the patient should have a follow-up test performed to confirm the test result. However, if the test is negative, it is more likely to be a true negative (high NPV), and the patient can be confident that they do not have COVID-19.

Conversely, if the test is being used in a symptomatic patient (higher probability of disease), a positive test is more likely to be a true positive (high PPV). In this case, the patient can be fairly certain that they have COVID-19. However, if the test is negative, it is more likely to be a false negative (low NPV), and the patient should have a follow-up test performed to confirm results.

What are the advantages and disadvantages of at-home tests?

All tests (e.g., PCT, antigen, NAAT) have advantages and disadvantages. The main advantages of at-home tests are that they can be administered without leaving home and provide results quickly.

Test results must be interpreted in the context of time from a possible exposure. Remember that following an exposure, it may take 5–7 days for the test to be able to detect the presence of the virus in an infected person.

What does it mean to be CLIA-waved?

Clinical Laboratory Improvement Amendments (CLIA) outlines national safety and quality standards for nonresearch laboratory testing to establish regulatory standards for the purposes of diagnosis, prevention, or treatment in human species.

Complexity of tests is based on numerous factors including user interpretation requirements, calibration and quality control requirements, degree of independent judgment needed, difficulty of performance calculations, intricacy of methodologies, and degree of training needed to perform a test. Tests that are assigned moderate- to high-level complexity are required to be performed in a certified laboratory setting. Companies can apply for tests to be CLIA-waived based on complexity status to allow them to be used at home. These are not meant to be used as “in-office” or “professional-use-only” devices.

Can my pharmacy provide an “official record” suitable for work, school, and travel?

Home tests that are not taken under direct observation may not be sufficient for travel if negative test results are required. However, tests that have companion applications that allow uploading of results and display proof of testing results may be suitable for work and school records. If pharmacies have the technological capabilities, a record of test results could potentially be provided via a phone application with a patient’s medication and immunization records as a health “passport.” ■