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Volume 27, Number 9—September 2021

Predictors of Nonseroconversion after SARS-CoV-2 Infection

Weimin Liu1, Ronnie M. Russell1, Frederic Bibollet-Ruche1, Ashwin N. Skelly1, Scott Sherrill-Mix1, Drew A. Freeman1, Regina Stoltz, Emily Lindemuth, Fang-Hua Lee, Sarah Sterrett, Katharine J. Bar, Nathaniel Erdmann, Sigrid Gouma, Scott E. Hensley, Thomas Ketas, Albert Cupo, Victor M. Cruz Portillo, John P. Moore, Paul D. Bieniasz, Theodora Hatziioannou, Greer Massey, Mary-Beth Minyard2, Michael S. Saag, Randall S. Davis, George M. Shaw, William J. Britt, Sixto M. Leal, Paul Goepfert, and Beatrice H. HahnComments to Author 
Author affiliations: University of Pennsylvania, Philadelphia, Pennsylvania, USA (W. Liu, R.M. Russell, F. Bibollet-Ruche, A.N. Skelly, S. Sherrill-Mix, R. Stoltz, E. Lindemuth, F.-H. Lee, K.J. Bar, S. Gouma, S.E. Hensley, G.M. Shaw, B.H. Hahn); The University of Alabama at Birmingham, Birmingham, Alabama, USA (D.A. Freeman, S. Sterrett, N. Erdmann, M.S. Saag, R.S. Davis, W.J. Britt, S.M. Leal Jr., P. Goepfert); Weill Cornell Medicine, New York, New York, USA (T. Ketas, A. Cupo, V.M. Cruz Portillo, J.P. Moore); Howard Hughes Medical Institute, New York (P.D. Bieniasz); The Rockefeller University, New York (P.D. Bieniasz, T. Hatziioannou); Assurance Scientific, Vestavia, Alabama, USA (G. Massey, M.-B. Minyard)

Main Article


Demographic, clinical, and laboratory characteristics of serologic responders and nonresponders after SARS-CoV-2 infection*

Characteristic SARS-CoV-2 antibody positive, n = 46 SARS-CoV-2 antibody negative, n = 26 p value†
Age, y, median (IQR)
49 (37–63)
35 (30–46)
Sex 0.17
M 30 (65) 10 (38)
16 (35)
16 (62)

Race/ethnicity 1.00
White 28 (61) 20 (77)
Black 7 (15) 3 (12)
Asian 7 (15) 3 (12)
4 (9)

RT-PCR of nasal swabs
DFOS, d, median (IQR) 5 (3–11) 5 (4–8) 0.95
Ct value, median (IQR)‡
24.5 (22–27)
36 (34–77)
Symptoms§ 45 (98) 25 (96) 0.21
Severity 0 1 (2) 1 (4)
Severity 1 5 (11) 8 (31)
Severity 2 33 (72) 15 (58)
Severity 3
7 (15)
2 (8)

6 (13)
2 (8)
Serologic analyses
DFOS of T1, d, median (IQR)
34 (26–46)
33 (22–43)
Binding antibodies (positive¶)
Spike protein (IgG)# 46 (100) 0
Spike protein (IgA)# 43 (93) 0
RBD (IgG)** 44 (96) 0
RBD (IgM)** 38 (83) 0
Nucleocapsid protein (IgG)††
43 (93)

Neutralizing antibodies (positive¶) 45 (98) 0

*Participants were a convenience sample recruited at the University of Alabama at Birmingham (Birmingham, AL, USA) during March–May 2020. Values are no. (%) unless otherwise indicated. Ct, cycle threshold; DFOS, days following onset of symptoms; IQR, interquartile range; RBD, receptor binding domain; RT-PCR, reverse transcription PCR; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; T1, time of first serologic test. †Calculated using a likelihood ratio test for a logistic regression predicting seropositivity for the category indicated after Bonferroni correction for multiple comparisons, except for RT-PCR and serologic DFOS, for which p-values were calculated using a Welch’s 2-sample t-test. ‡Ct values were only available for a subset of seropositive (n = 34) and seronegative (n = 25) persons Appendix Table 1. §Symptom severity was self-reported, with 0 indicating no symptoms, 1 indicating mild symptoms with little impact on daily activities, 2 indicating moderate symptoms with noticeable impact on daily activities, and 3 indicating severe symptoms with a substantial reduction in quality of life (Appendix Table 1). ¶Above assay detection limits (Appendix Table 2 details midpoint and endpoint titers). #ELISA detection of IgG and IgA binding antibodies to a prefusion stabilized Wuhan-Hu-1 spike protein. **ELISA detection of IgM and IgG binding antibodies to RBD of the Wuhan-Hu-1 spike protein. ††Detection of IgG binding antibodies to the nucleocapsid protein by the Abbott Architect assay.

Main Article

1These first authors contributed equally to this article.

2Current affiliation: MBMicrobio Labs, Birmingham, Alabama, USA.

Page created: June 30, 2021
Page updated: August 18, 2021
Page reviewed: August 18, 2021
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