Neutralizing Antibody Production in Asymptomatic and Mild COVID-19 Patients, in Comparison with Pneumonic COVID-19 Patients

• Published in: Journal of clinical medicine 2020-07, Vol.9 (7), p.2268
• Main Authors: Ko, Jae-Hoon, Joo, Eun-Jeong, Park, Su-Jin, Baek, Jin Yang, Kim, Won Duk, Jee, Jaehwan, Kim, Chul Joong, Jeong, Chul, Kim, Yae-Jean, Shon, Hye Jin, Kang, Eun-Suk, Choi, Young Ki, Peck, Kyong Ran
• Format: Article
• Language: English
• Subjects: Antibodies; Asymptomatic; Clinical medicine; Coronaviruses; COVID-19; Disease transmission; Illnesses; Infections; Olfaction disorders; Patients; Pneumonia; Population; Severe acute respiratory syndrome coronavirus 2; Viral infections
• ISSN: 2077-0383; 2077-0383
• DOI: 10.3390/jcm9072268

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.