tetano
Editor, Senior Moderator
Ann Lab Med
. 2021 Nov 1;41(6):568-576.
doi: 10.3343/alm.2021.41.6.568.
Combination of a SARS-CoV-2 IgG Assay and RT-PCR for Improved COVID-19 Diagnosis
Kotaro Aoki[SUP] 1 [/SUP], Kunitomo Takai[SUP] 2 [/SUP], Tatsuya Nagasawa[SUP] 1 [/SUP], Katsuhito Kashiwagi[SUP] 3 [/SUP], Nobuaki Mori[SUP] 4 [/SUP], Keiji Matsubayashi[SUP] 5 [/SUP], Masahiro Satake[SUP] 5 [/SUP], Ippei Tanaka[SUP] 2 [/SUP], Nanae Kodama[SUP] 6 [/SUP], Takahiro Shimodaira[SUP] 6 [/SUP], Yoshikazu Ishii[SUP] 1 [/SUP], Taito Miyazaki[SUP] 3 [/SUP], Toshiaki Ishii[SUP] 6 [/SUP], Toshisuke Morita[SUP] 7 [/SUP], Toru Yoshimura[SUP] 2 [/SUP], Kazuhiro Tateda[SUP] 1 [/SUP]
Affiliations
Abstract
Background: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is generally diagnosed by reverse transcription (RT)-PCR or serological assays. The SARS-CoV-2 viral load decreases a few days after symptom onset. Thus, the RT-PCR sensitivity peaks at three days after symptom onset (approximately 80%). We evaluated the performance of the ARCHITECT[SUP]®[/SUP] SARS-CoV-2 IgG assay (henceforth termed IgG assay; Abbott Laboratories, Lake County, IL, USA), and the combination of RT-PCR and the IgG assay for COVID-19 diagnosis.
Methods: In this retrospective study, 206 samples from 70 COVID-19 cases at two hospitals in Tokyo that were positive using RT-PCR were used to analyze the diagnostic sensitivity. RT-PCR-negative (N=166), COVID-19-unrelated (N=418), and Japanese Red Cross Society (N=100) samples were used to evaluate specificity.
Results: Sensitivity increased daily after symptom onset and exceeded 84.4% after 10 days. Specificity ranged from 98.2% to 100% for samples from the three case groups. Seroconversion was confirmed from 9 to 20 days after symptom onset in 18 out of 32 COVID-19 cases with multiple samples and from another case with a positive result in the IgG assay for the first available sample.
Conclusions: The combination of RT-PCR and IgG assay improves the robustness of laboratory diagnostics by compensating for the limitations of each method.
Keywords: ARCHITECT®; COVID-19; Immunoassay; Reverse transcription (RT)-PCR; SARS-CoV-2 IgG; Sensitivity; Specificity.
. 2021 Nov 1;41(6):568-576.
doi: 10.3343/alm.2021.41.6.568.
Combination of a SARS-CoV-2 IgG Assay and RT-PCR for Improved COVID-19 Diagnosis
Kotaro Aoki[SUP] 1 [/SUP], Kunitomo Takai[SUP] 2 [/SUP], Tatsuya Nagasawa[SUP] 1 [/SUP], Katsuhito Kashiwagi[SUP] 3 [/SUP], Nobuaki Mori[SUP] 4 [/SUP], Keiji Matsubayashi[SUP] 5 [/SUP], Masahiro Satake[SUP] 5 [/SUP], Ippei Tanaka[SUP] 2 [/SUP], Nanae Kodama[SUP] 6 [/SUP], Takahiro Shimodaira[SUP] 6 [/SUP], Yoshikazu Ishii[SUP] 1 [/SUP], Taito Miyazaki[SUP] 3 [/SUP], Toshiaki Ishii[SUP] 6 [/SUP], Toshisuke Morita[SUP] 7 [/SUP], Toru Yoshimura[SUP] 2 [/SUP], Kazuhiro Tateda[SUP] 1 [/SUP]
Affiliations
- PMID: 34108284
- DOI: 10.3343/alm.2021.41.6.568
Abstract
Background: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is generally diagnosed by reverse transcription (RT)-PCR or serological assays. The SARS-CoV-2 viral load decreases a few days after symptom onset. Thus, the RT-PCR sensitivity peaks at three days after symptom onset (approximately 80%). We evaluated the performance of the ARCHITECT[SUP]®[/SUP] SARS-CoV-2 IgG assay (henceforth termed IgG assay; Abbott Laboratories, Lake County, IL, USA), and the combination of RT-PCR and the IgG assay for COVID-19 diagnosis.
Methods: In this retrospective study, 206 samples from 70 COVID-19 cases at two hospitals in Tokyo that were positive using RT-PCR were used to analyze the diagnostic sensitivity. RT-PCR-negative (N=166), COVID-19-unrelated (N=418), and Japanese Red Cross Society (N=100) samples were used to evaluate specificity.
Results: Sensitivity increased daily after symptom onset and exceeded 84.4% after 10 days. Specificity ranged from 98.2% to 100% for samples from the three case groups. Seroconversion was confirmed from 9 to 20 days after symptom onset in 18 out of 32 COVID-19 cases with multiple samples and from another case with a positive result in the IgG assay for the first available sample.
Conclusions: The combination of RT-PCR and IgG assay improves the robustness of laboratory diagnostics by compensating for the limitations of each method.
Keywords: ARCHITECT®; COVID-19; Immunoassay; Reverse transcription (RT)-PCR; SARS-CoV-2 IgG; Sensitivity; Specificity.