Reliability of at home rapid-COVID tests

Can we trust the at home rapid COVID tests?

 This is a great question that we are asked often.  There are many variables to consider

1. Are symptoms present?

Rapid tests are most accurate for those who have symptoms of illness, ideally including runny nose and/or nasal congestion.

2. Was there a confirmed exposure to someone with COVID-19 illness?

If there was a confirmed exposure to COVID-19 illness and rapid testing (at home or in a medical office) was negative, a PCR test needs to be done.  Please refer to our handout to choose the right time for PCR testing: COVID-19: Exposure, testing, and quarantine

3.  What test should I choose?

We recommend choosing one with Emergency Use Authorization (EUA) from the FDA. A list of at home EUA Antigen Diagnostic Tests for SARS-CoV-2 can be found here:  EUA Rapid-COVID test list.  “There are nine SARS-CoV-2 antigen tests from five companies now authorized by the FDA” with EUA; the 3 most readily available locally include Abbot BinaxNow (Abbott Test FAQ), Ellume COVID-19 Home Test (Ellume Test FAQ), and Quidel Quick Vue (QuickVue Test FAQ).

4. Can I trust results of an at-home rapid antigen test?

The short answer is that if the person being tested has symptoms of illness and the EUA authorized test shows a clear positive line (not a faint positive or barely visible line), you can trust that the results are actually positive, and retesting in our office is not needed.  This is assuming that the swab contained enough sample to test, the tester followed all the manufacturer’s instructions, and the person was tested at the correct time.  This handout offers guidance on the ideal time to test: COVID-19: Exposure, testing, and quarantine. 

Most EUA SARS-CoV-2 rapid-antigen tests, have high specificity (a low rate of false positive) for those with symptoms of illness. This means that a positive is really a positive.  Our in office rapid antigen test is 100% specific for those with symptoms of illness, meaning that positive results are 100% accurate. 

• Abbott BinaxNow:
  • “84 % accurate at detecting positive cases and 98% accurate at detecting negative cases.” 
  • Specificity = 98.5% with symptoms of illness (positive results are 98.5% accurate)
• Ellume COVID-19 Home Test:
  • “96% accuracy for those who had symptoms and 91% accuracy” for those without symptoms
  • Specificity = 97% with symptoms of illness (positive results are 97% accurate)
• Quidel Quick Vue:
  • “83% accuracy for detecting positive cases and 99% accuracy detecting negative cases” 
  • Specificity = 99.1% with symptoms of illness (positive results are 99.1% accurate)

 5.  Do I need to retest and what should I do with my results?

• If results are positive: If you have a clear positive line (not a faint positive or barely visible line) and have symptoms of illness you can believe that COVID-19 illness is present and retesting in our office is not useful.  Instead, we recommend a telemedicine visit to review results, talk about symptoms and treatment, and review quarantine.  After this visit, we can also provide a note for school.   For information about duration of quarantine and need for testing of others in the household, this handout should offer guidance: COVID-19: Exposure, testing, and quarantine. 
• If results are negative or uncertain (this includes at home tests with a faint positive or barely visible line)
  • As long as there is no known exposure to COVID-19 illness, and school does not need a note from our office documenting these results, retesting is not needed. Unless we test via our in office rapid-antigen test or PCR test or see documented results from another site who performed testing, we cannot write a school note.
  • If school does need a note from us documenting negative results, we are happy to see your child in our office for an appointment.
  • If there is a known exposure to COVID-19 illness, and rapid testing (at home or in a medical office) is negative, PCR testing is still needed. See our handout for the ideal timing of PCR testing: COVID-19: Exposure, testing, and quarantine. 

References:

• https://www.wcnc.com/article/news/verify/verify-yes-at-home-covid-19-tests-are-reliable-to-determine-whether-youve-been-infected/275-89e83e06-f7c1-4b1b-bb78-d8cea92dc906elated Articles
• https://www.nbcnews.com/shopping/wellness/best-home-covid-tests-n1275687
• https://open.fda.gov/apis/device/covid19serology/
• https://www.cdc.gov/mmwr/volumes/70/wr/mm7003e3.htm#T1_down
• https://www.nytimes.com/wirecutter/blog/at-home-covid-antigen-tests/