An Update on Potential “False Positive” Tests – Discordance Between Antigen and PCR Tests

COVID-19; Research and Data

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Starting last week, we heard concerning reports of differences between the antigen tests and PCR confirmation test results (e.g. potential false positives) from the antigen testing machines HHS has sent to nursing homes. To better understand what’s going on across the country, AHCA and Leading Age collaborated on a survey to understand the use of the BD Veritor and Quidel Sofia-2 Antigen Point of Care analyzers in member communities.

We heard back from over 1,100 respondents—thank you to those of you who participated. Approximately 939 of whom are using either the BD or Quidel analyzers. We found that about 20-25 percent of SNFs had a positive antigen test result later found to be incorrect using PCR testing. The vast majority had only 1-3 “potential false positives”; 26 (or 3 percent) had more than 5 potential false positives. 

While any potential false positive results are concerning, this appears to be consistent with what you would expect to see with widespread testing of many people in communities with relative low rates of COVID-19. Nonetheless, BD and Quidel are investigating to make sure there are no issues. Preliminary investigation from a few reports received last week have not revealed any abnormalities. It’s important for all providers to double check they are following the manufacturer’s protocols and have staff appropriately trained on the use of each analyzer. 

We continue to ask you to report potential false positives to the manufactures: 

For BD Veritor potential false positives providers should:
  • ​Call 1-800-638-8663 for providers who experience potential false positives (note: press 2 for technical support and then 1 for Veritor support); or
  • Email BD at Technical_Services@bd.com 
  • BD offers this microsite and these training webinars​ which we encourage members to review if they are having concerns with accuracy to make sure they are following all the instructions correctly. 
For Quidel potential false positives, providers should: 
  • ​Call 1-800-874-1517, option 2, then option 1 for providers who experience potential false positives 
  • Email Quidel at Technical Support (Quidel San Diego) technicalsupport@quidel.com
  • Visit togetheragain.quidel.com to view online training​ modules
  • Quidel offers live training seminars every Tuesday and Thursday at 12 PM EST which we encourage members to attend if they are having concerns with accuracy to make sure they are following all the instructions correctly. You need to complete the entire training program AND receive a certificate of completion. 
Members should continue to use these POC antigen tests, but we encourage providers to follow the CDC guidance and algorithm on when to conduct confirmation testing of positive antigen tests. We also would encourage members to conduct confirmation testing with PCR tests in other situations not covered by CDC guidance where asymptomatic residents or staff test positive with the antigen tests given the recent reports of potential false positives. 

  • If asymptomatic residents test positive with an POC antigen test, they should be placed into transmission-based precautions and a single room, if possible, but not moved to a COVID-19 positive unit, wing or floor or cohorted with a known positive resident until confirmation testing with PCR is obtained. 
Most important, the potential false positive reports emphasize the need for communication from HHS on how to handle these cases, which will happen even with PCR testing. We understand that members are receiving different directives from their state health departments ranging from being required to report all positive test results, even if they are found to conflict with confirmation testing, to being advised not to use the antigen analyzers. We are working aggressively with HHS to get written information out to address what to do in the case of potential false positives, whether from antigen or PCR tests. This includes recommendations for cohorting and isolation; reporting to the state and to the NHSN; not treating a potential false positive as an outbreak; implications for Provider Relief Fund performance incentive payments.​