Follow-up testing of borderline SARS-CoV-2 patients by rRT-PCR allows early diagnosis of COVID-19

Link to article at PubMed

Diagn Microbiol Infect Dis. 2021 Feb 18;100(2):115350. doi: 10.1016/j.diagmicrobio.2021.115350. Online ahead of print.


Detection of SARS-CoV-2 RNA in nasopharyngeal samples using the real-time reverse transcription polymerase chain reaction (rRT-PCR) is the gold standard for diagnosing COVID-19. Determination of SARS-CoV-2 RNA by rRT-PCR sometimes results in an inconclusive test result due to a high cycle threshold-value. We retrospectively analyzed 30,851 SARS-CoV-2 rRT-PCR test results. Borderline positivity was considered as the presence of ≤25 viral copies per milliliter, while no amplification was considered as a negative test result. Of all test results, 204 were answered as borderline, of which 107 were accompanied by a follow-up test within 96 hours. Of the 107 follow-up samples, 10 (9.35%) were found positive for SARS-CoV-2. COVID-19 symptoms were not predictive for testing positive in the follow-up test. The positive SARS-CoV-2 samples in the follow-up group represented 0.92% of all positive test results, highlighting the need for retesting and increased hygienic measures for borderline SARS-CoV-2 patients [NCT04636294].

PMID:33689985 | PMC:PMC7891066 | DOI:10.1016/j.diagmicrobio.2021.115350

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