Original ArticlesEffectiveness of Rapid Antigen Testing in Forensic Cases of Severe Acute Respiratory Syndrome Coronavirus 2 Infection, Including Delta VariantMatsumoto, Sari MD, PhD∗; Takasu, Shojiro MD, PhD∗; Shimmura, Suzuka MD∗; Iwadate, Kyoko MD∗; Sakai, Ami MMS∗; Kanto, Yuko PhD∗; Sakurai, Tatsuya DVM, PhD†; Ote, Manabu PhD‡; Saiki, Erisha PhD†; Kanuka, Hirotaka PhD‡; Iwadate, Kimiharu MD, PhD∗ Author Information From the ∗Department of Forensic Medicine †Laboratory Animal Facilities ‡Department of Tropical Medicine, The Jikei University School of Medicine, Tokyo, Japan. Manuscript received May 27, 2022; accepted August 6, 2022. This work was supported by the Ministry of Health, Labor, and Welfare, KAKENHI (grant number 20CA2075). The authors report no conflict of interest. S.M. designed the study, performed rapid antigen testing, interpreted the data, performed statistical analyses, and wrote the initial draft of the manuscript. S.T. performed rapid antigen testing and statistical analyses. S.S. performed rapid antigen testing and participated in collecting and summarizing the data. Kyoko I. performed rapid antigen testing and the literature search. A.S. performed rapid antigen testing and participated in collecting and summarizing the data. Y.K. performed rapid antigen testing and managed information. T.S. performed RT-qPCR. M.O. performed RT-qPCR. E.S. performed RT-qPCR. H.K. performed RT-qPCR and participated in manuscript writing. Kimiharu I. performed rapid antigen testing, contributed to data analysis, and assisted in the preparation of the manuscript. All authors approved the final version of the manuscript and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Reprints: Sari Matsumoto, MD, PhD, Department of Forensic Medicine, The Jikei University School of Medicine, Nishishinbashi 3-25-8, Minato-ku, Tokyo 105-8461, Japan. E-mail: [email protected]. The American Journal of Forensic Medicine and Pathology: December 2022 - Volume 43 - Issue 4 - p 305-310 doi: 10.1097/PAF.0000000000000792 Buy Metrics Abstract The polymerase chain reaction is indispensable for diagnosing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in forensic cases. However, studies regarding the effectiveness of rapid antigen testing (RAT) in forensic cases remain limited. Therefore, we investigated the efficacy of RAT compared with reverse–transcription quantitative polymerase chain reaction (RT-qPCR) for confirming SARS-CoV-2 infection (including the delta variant). Before the external examination or autopsy, we collected samples from the nasopharyngeal mucosa, which were then assessed via RAT (QuickNavi COVID-19 Ag kit, QuickNavi-Flu+COVID-19 Ag kit) and RT-qPCR. Reverse-transcription quantitative polymerase chain reaction results were positive in 73 of 1255 cases, and 21 cases were identified as those of delta variants. Low RT-qPCR threshold cycle value cases and delta variant infections were more likely to result in coronavirus disease-related deaths. The sensitivity of the QuickNavi COVID-19 Ag kit was 76.32%, and that of the QuickNavi-Flu+COVID-19 Ag kit was 77.14%. The specificity of both RATs was 100%. In QuickNavi COVID-19 Ag kit cases, delta variant cases showed lower sensitivity than non-delta variant cases, even for a similar viral load. Thus, RAT in forensic cases is sufficiently useful as a screening test for SARS-CoV-2 infection. However, RAT carries a risk of false negatives, especially for delta variant cases. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.