evaluation of false negative among sars-cov-2 patients with negative real-time pcr result using nested-rt pcr

Background: fast and precise detection of sars-cov-2 rna in clinical samples and subsequent quarantine are two critical factors in preventing virus transmission and distribution through the community. the false-negative result is a major problem in the sarscov- 2 detection because of the kind of sample (swab sample), sampling error, and sensitivity of pcr test, which can be reduced by a much more sensitive test such as nested pcr. objectives: this study aimed to evaluate the false-negative rate among samples that were negative by a real-time pcr test using rt-nested pcr. methods: one hundred eighty-four negative samples were included in the study, and nucleic acid was extracted using a commercial kit based on a silica filter column and then subjected to rt-nested pcr using three sets of primers targeting orf1ab, n, and rdrp regions. results: among 184 negative swab samples for sars-cov-2, 27 (14.6%) cases were positive for the orf1ab gene using rt-nested pcr. the samples were tested using n and rdrp primer sets. also, seven (3.8%) cases were positive for the n gene, and four (2.1%) cases were positive for the rdrp gene. conclusions: the results indicated that rt-nested pcr could be more sensitive than real-time pcr and reduce the false-negative rate.