Back to normal; serological testing for COVID-19 diagnosis unveils missed infections.

The gold standard for coronavirus disease (COVID-19) diagnosis has been the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA by nucleic acid amplification testing (NAAT). On the other hand, serological testing for COVID-19 may offer advantages in detecting possibly overlooked infections by NAAT. To evaluate seroconversion of NAAT-negative pneumonia patients, immunoglobulin M (IgM) and IgG targeting the spike protein of SARS-CoV-2 were semiquantified by an immunofluorescence assay. Seroconversion was confirmed by another serological method, targeting the nucleocapsid protein. Eight suspected but unconfirmed COVID-19 pneumonia patients (median age, 39 years; range, 21-55) were included. The median period between symptom onset and NAAT sample collection was 6 days (2-27 days). None of them had tested positive for SARS-CoV-2 by NAAT. In contrast, all eight patients revealed seropositivity with the two serological methods, indicating actual seroconversion against SARS-CoV-2. The median period between onset and blood sampling was 26.5 days (7-51 days). Eight patients with COVID-19 pneumonia, initially tested negative for SARS-CoV-2 by NAAT, were finally confirmed of the diagnosis by serological testing. To cover the whole spectrum of this heterogenous infectious disease, serology testing should be implemented to the multitiered diagnostic algorithm for COVID-19.

Tsuchida T ，Nitahara Y ，Suzuki S ，Komase Y ，Candray K ，Kido Y ，Nakagama Y ，Yamasaki Y ，Imamura M ，Kawahata K ，Kunishima H ，Fujitani S ，Mineshita M ，Matsuda T ... -  《-》

Comparison of 2 fully automated tests detecting antibodies against nucleocapsid N and spike S1/S2 proteins in COVID-19.

Automated assays for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in coronavirus disease 2019 (COVID-19) diagnostics have recently come available. We compared the performance of the Elecsys® Anti-SARS-CoV-2 and LIAISON® SARS-CoV-2 S1/S2 IgG tests. The seroconversion panel comprised of 120 samples from 13 hospitalized COVID-19 patients. For the sensitivity and specificity testing, samples from COVID-19 outpatients >15 days after positive nucleic acid amplification test (NAAT) result (n = 35) and serum control samples collected before the COVID-19 era (n = 161) were included in the material. Samples for the detection of possible cross-reactions were also tested. Based on our results, the SARS-CoV-2 antibodies can be quite reliably detected 2 weeks after NAAT positivity and 3 weeks after the symptom onset with both tests. However, since some COVID-19 patients were positive only with Elecsys®, the antibodies should be screened against N-antigen (Elecsys®) and reactive samples confirmed with S antigen (LIAISON®), but both results should be reported. In some COVID-19 patients, the serology can remain negative.

Flinck H ，Rauhio A ，Luukinen B ，Lehtimäki T ，Haapala AM ，Seiskari T ，Aittoniemi J ... -  《-》

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》

A Serological Snapshot of COVID-19 Initial Stages in Israel by a 6-Plex Antigen Array.

Fisher M ，Levy H ，Fatelevich E ，Afrimov Y ，Ben-Shmuel A ，Rosenfeld R ，Noy-Porat T ，Glinert I ，Sittner A ，Biber A ，Belkin A ，Bar-David E ，Puni R ，Levy I ，Mazor O ，Weiss S ，Mechaly A ... -  《Microbiology Spectrum》

Pediatric evaluation of clinical specificity and sensitivity of SARS-CoV-2 IgG and IgM serology assays.

Bohn MK ，Hall A ，Wilson S ，Taher J ，Sepiashvili L ，Adeli K ... -  《-》