Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections

• Published in: Nature medicine Vol. 26; no. 8; pp. 1200 - 1204
• Main Authors: Long, Quan-Xin, Tang, Xiao-Jun, Shi, Qiu-Lin, Li, Qin, Deng, Hai-Jun, Yuan, Jun, Hu, Jie-Li, Xu, Wei, Zhang, Yong, Lv, Fa-Jin, Su, Kun, Zhang, Fan, Gong, Jiang, Wu, Bo, Liu, Xia-Mao, Li, Jin-Jing, Qiu, Jing-Fu, Chen, Juan, Huang, Ai-Long
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.08.2020; Nature Publishing Group
• Subjects: 692/699/255; 692/699/255/2514; Adolescent; Adult; Aged; Antibodies; Asymptomatic; Asymptomatic Infections; Betacoronavirus - immunology; Betacoronavirus - pathogenicity; Biomedical and Life Sciences; Biomedicine; Cancer Research; Carbon monoxide; Child; China - epidemiology; Coronavirus Infections - blood; Coronavirus Infections - epidemiology; Coronavirus Infections - immunology; Coronavirus Infections - virology; Coronaviruses; COVID-19; Cytokines; Cytokines - blood; Cytokines - immunology; Female; Genetic testing; Health aspects; Hospitalization; Humans; Immune response; Immune system; Immunity, Innate; Immunoglobulin G; Immunoglobulin G - blood; Immunoglobulin G - immunology; Immunology; Infectious Diseases; Inflammation; Letter; Male; Metabolic Diseases; Middle Aged; Molecular Medicine; Neurosciences; Neutralizing; Pandemics; Patients; Physiological aspects; Pneumonia, Viral - blood; Pneumonia, Viral - epidemiology; Pneumonia, Viral - immunology; Pneumonia, Viral - virology; Reduction; SARS-CoV-2; Serological surveys; Severe acute respiratory syndrome coronavirus 2; Testing; Viral diseases; Viruses; Young Adult; China
• ISSN: 1078-8956; 1546-170X; 1546-170X
• DOI: 10.1038/s41591-020-0965-6

The clinical features and immune responses of asymptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well described. We studied 37 asymptomatic individuals in the Wanzhou District who were diagnosed with RT–PCR-confirmed SARS-CoV-2 infections but without any relevant clinical symptoms in the preceding 14 d and during hospitalization. Asymptomatic individuals were admitted to the government-designated Wanzhou People’s Hospital for centralized isolation in accordance with policy 1 . The median duration of viral shedding in the asymptomatic group was 19 d (interquartile range (IQR), 15–26 d). The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P  = 0.028). The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6–10.7) were significantly lower ( P  = 0.005) relative to the symptomatic group (median S/CO, 20.5; IQR, 5.8–38.2) in the acute phase. Of asymptomatic individuals, 93.3% (28/30) and 81.1% (30/37) had reduction in IgG and neutralizing antibody levels, respectively, during the early convalescent phase, as compared to 96.8% (30/31) and 62.2% (23/37) of symptomatic patients. Forty percent of asymptomatic individuals became seronegative and 12.9% of the symptomatic group became negative for IgG in the early convalescent phase. In addition, asymptomatic individuals exhibited lower levels of 18 pro- and anti-inflammatory cytokines. These data suggest that asymptomatic individuals had a weaker immune response to SARS-CoV-2 infection. The reduction in IgG and neutralizing antibody levels in the early convalescent phase might have implications for immunity strategy and serological surveys. A cohort of asymptomatic patients infected with SARS-CoV-2 had significantly lower levels of virus-specific IgG antibodies compared to a cohort of age- and sex-matched symptomatic infected patients.