Abstract
Objectives: To investigate antibody production in asymptomatic and mild COVID-19 patients. Methods: Sera from asymptomatic to severe COVID-19 patients were collected. Microneutralization (MN), fluorescence immunoassay (FIA), and enzyme-linked immunosorbent assay (ELISA) were performed. Results: A total of 70 laboratory-confirmed COVID-19 patients were evaluated, including 15 asymptomatic/anosmia, 49 mild symptomatic, and 6 pneumonia patients. The production of the neutralizing antibody was observed in 100% of pneumonia, 93.9% of mild symptomatic, and 80.0% of asymptomatic/anosmia groups. All the patients in the pneumonia group showed high MN titer (≥1:80), while 36.7% of mild symptomatic and 20.0% of asymptomatic/anosmia groups showed high titer (p < 0.001). Anti-SARS-CoV-2 antibodies could be more sensitively detected by FIA IgG (98.8%) and ELISA (97.6%) in overall. For the FIA IgG test, all patients in the pneumonia group exhibited a high COI value (≥15.0), while 89.8% of mild symptomatic and 73.3% of asymptomatic/anosmia groups showed a high value (p = 0.049). For the ELISA test, all patients in the pneumonia group showed a high optical density (OD) ratio (≥3.0), while 65.3% of mild symptomatic and 53.3% of asymptomatic/anosmia groups showed a high ratio (p = 0.006). Conclusions: Most asymptomatic and mild COVID-19 patients produced the neutralizing antibody, although the titers were lower than pneumonia patients. ELISA and FIA sensitively detected anti-SARS-CoV-2 antibodies.
Highlights
Over twelve million cases of coronavirus disease 2019 (COVID-19) have been reported worldwide as of 12 July 2020 [1]
We evaluated the serologic response of asymptomatic and mild COVID-19 patients using microneutralization (MN), fluorescence immunoassay (FIA), and enzyme-linked immunosorbent assay (ELISA), in comparison with moderate to severe COVID-19 patients with pneumonia
For the patients managed at the residential care center, one serum specimen was collected per patient on the day of discharge, while 18 serum specimens were obtained from the pneumonia group on different days after the 1st week of illness
Summary
Over twelve million cases of coronavirus disease 2019 (COVID-19) have been reported worldwide as of 12 July 2020 [1]. On 18 February 2020, the 31th patient was detected and a close association with a religious group, Shincheonji, was identified. A large regional outbreak occurred around Daegu metropolitan city in association with the Shincheonji religious group, which overwhelmed the healthcare capacity of the region [4]. Residential care centers designated for asymptomatic and mild COVID-19 patients were operated to alleviate the burden on hospitals using education centers of major corporations [6]. Such efforts slowed the spread of SARS-CoV-2 and led to the discovery of a large number of asymptomatic and mild COVID-19 patients [7]. The epidemiologic significance of asymptomatic and mild COVID-19 patients has been emphasized, since this population shed considerable viral load without noticeable symptoms and could be remained as undetected cases by symptom-based screening strategies [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
