Serological assay for anti-SARS-CoV-2 antibodies improves sensitivity of diagnosis of COVID-19 patients.

The emergence of SARS-CoV-2, responsible for coronavirus disease-2019 (COVID-19), has become a major global health problem. The molecular testing is the accepted assay in SARS-CoV-2 detection. However, there are several reasons for low sensitivity by RNA detection, causing challenges in SARS-CoV-2 diagnosis. In this study, we aimed to investigate serological patterns of SARS-CoV-2 specific IgM, and IgG in 111 hospitalized, and 34 recovered COVID-19 patients and 311 prepandemic normal serum specimens by ELISA. The validity of the ELISA kits was evaluated using samples from normal and recovered cases. This showed that 98.1%, and 98.4% of prepandemic normal samples were negative for anti-SARS-CoV-2 IgM, and IgG, respectively. Assessment of 34 COVID-19 confirmed recovered patients showed a test sensitivity of 76.5%, and 94.1% for IgM, and IgG, respectively. In COVID-19 hospitalized patients, 42.3%, and 51.4% were positive for IgM and IgG, respectively. Viral RNA was not detectable in 43.3% of the hospitalized patients. Interestingly, combined molecular and serological testing improved the sensitivity of COVID-19 diagnosis to 79.6%. Using PCR with combined IgM/IgG results augmented the patient diagnosis sensitivity to 65.3% and 87.2% in ≤ 7 days, and > 7 days intervals, respectively. Overall, serological tests in combination with PCR can improve the sensitivity of COVID-19 diagnosis.

Rostamzadeh D ，Mortezagholi S ，Alinejad M ，Jooya SR ，Eskandarian M ，Metvaei A ，Vafaei S ，Aboulghasemi H ，Younesi V ，Shabani M ... -  《-》

Evaluation of serum IgM and IgG antibodies in COVID-19 patients by enzyme linked immunosorbent assay.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is sweeping the world since the end of 2019. The titer change of antibodies against SARS-CoV-2 needs to be further clarified, the clinical and preventive value of antibodies still needs to be further investigated. An enzyme-linked immunosorbent assay (ELISA) was established by coating with SARS-CoV-2 recombinant spike protein and used to detect serum immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against SARS-CoV-2 in coronavirus disease 2019 patients to evaluate the pattern of changes of antibodies. The specificity of the ELISA for detection SARS-CoV-2 IgM and IgG were 96% (144/150) and 100% (150/150), respectively. The sensitivity of ELISA was 100% (150/150) for IgM, and 99.3% (149/150) for IgG. SARS-CoV-2-SP-IgM and SP-IgG antibodies could be detected on Day 1 of hospitalization in 12.5% patients, and SP-IgM began to decrease after reaching its peak at around 22-28 days, and become negative at Month 3 in 30% patients and negative at Month 7 in 79% of these patients after onset; IgG reached its peak around Day 22-28 and kept at a high level within the longest observation period for 4 months, it dropped very sharply at 7 months. The positive rates of SP-IgM and SP-IgG were higher than those of reverse transcription-polymerase chain reaction on Day 7 and 4. The established indirect ELISA has good specificity and sensitivity. IgM and IgG against SARS-CoV-2 appeared almost simultaneously in the early stage, and the level of IgG antibodies could not maintain a high plateau in the observation period of 7 months. Our data will help develop the diagnosis and vaccine of SARS-CoV-2.

Zhou C ，Bu G ，Sun Y ，Ren C ，Qu M ，Gao Y ，Zhu Y ，Wang L ，Sun L ，Liu Y ... -  《-》

Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera.

Ha B ，Jadhao S ，Hussaini L ，Gibson T ，Stephens K ，Salazar L ，Ciric C ，Taylor M ，Rouphael N ，Edupuganti S ，Rostad CA ，Tompkins SM ，Anderson EJ ，Anderson LJ ... -  《Microbiology Spectrum》

Validation of a new automated chemiluminescent anti-SARS-CoV-2 IgM and IgG antibody assay system detecting both N and S proteins in Japan.

Yokoyama R ，Kurano M ，Morita Y ，Shimura T ，Nakano Y ，Qian C ，Xia F ，He F ，Kishi Y ，Okada J ，Yoshikawa N ，Nagura Y ，Okazaki H ，Moriya K ，Seto Y ，Kodama T ，Yatomi Y ... -  《PLoS One》

Testing IgG antibodies against the RBD of SARS-CoV-2 is sufficient and necessary for COVID-19 diagnosis.

Indenbaum V ，Koren R ，Katz-Likvornik S ，Yitzchaki M ，Halpern O ，Regev-Yochay G ，Cohen C ，Biber A ，Feferman T ，Cohen Saban N ，Dhan R ，Levin T ，Gozlan Y ，Weil M ，Mor O ，Mandelboim M ，Sofer D ，Mendelson E ，Lustig Y ... -  《PLoS One》