Three SARS-CoV-2 PCR-negative cases of COVID-19 diagnosed using isothermal amplification methods.

Coronavirus disease (COVID-19) is a viral disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 can be detected by polymerase chain reaction (PCR) and isothermal nucleic acid amplification tests, including loop-mediated isothermal amplification (LAMP) and nicking endonuclease amplification reaction (NEAR) tests. Although PCR is the most sensitive and specific method and is generally considered to be the gold standard, it is time-consuming and costly. Isothermal nucleic acid amplification tests have lower sensitivity and specificity than PCR, but are less time-consuming and costly. We encountered three cases of SARS-CoV-2 infection in which the isothermal amplification test was positive but the PCR test was negative on the day of admission; however, the PCR test was positive the next day. These cases showed that some COVID-19 patients can test negative by PCR but positive using isothermal nucleic acid amplification methods. As PCR tests have the possibility of false-negative results, tests that use isothermal amplification methods which can be performed in a shorter time and at a lower cost than PCR tests, may be able to diagnose patients who have false negative PCR results.