Usage Information
Abstract
BACKGROUND Estimates of seroprevalence to SARS-CoV-2 vary widely and may influence vaccination response. We ascertained IgG levels across a single US metropolitan site, Chicago, from June 2020 through December 2020.METHODS Participants (n = 7935) were recruited through electronic advertising and received materials for a self-sampled dried-blood spot assay through the mail or a minimal contact in-person method. IgG against the receptor-binding domain of SARS-CoV-2 was measured using an established highly sensitive and highly specific assay.RESULTS Overall seroprevalence was 17.9%, with no significant difference between method of contact. Only 2.5% of participants reported having had a diagnosis of COVID-19 based on virus detection, consistent with a 7-fold greater exposure to SARS-CoV-2 measured by serology than that detected by viral testing. The range of IgG level observed in seropositive participants from this community survey overlapped with the range of IgG levels associated with COVID-19 cases having a documented positive PCR test. From a subset of those who participated in repeat testing, half of seropositive individuals retained detectable antibodies for 3 to 4 months.CONCLUSION Quantitative IgG measurements with a highly specific and sensitive assay indicated more widespread exposure to SARS-CoV-2 than observed by viral testing. The range of IgG concentrations produced from these asymptomatic exposures was similar to IgG levels occurring after documented nonhospitalized COVID-19, which were considerably lower than those produced from hospitalized COVID-19 cases. The differing ranges of IgG response, coupled with the rate of decay of antibodies, may influence response to subsequent viral exposure and vaccine.Funding National Science Foundation grant 2035114, NIH grant 3UL1TR001422-06S4, NIH National Center for Advancing Translational Sciences grants UL1 TR001422 and UL1 TR002389, Dixon Family Foundation, Northwestern University Cancer Center (NIH grant P30 CA060553), and Walder Foundation’s Chicago Coronavirus Assessment Network.
Authors
Alexis R. Demonbreun, Thomas W. McDade, Lorenzo Pesce, Lauren A. Vaught, Nina L. Reiser, Elena Bogdanovic, Matthew P. Velez, Ryan R. Hsieh, Lacy M. Simons, Rana Saber, Daniel T. Ryan, Michael G. Ison, Judd F. Hultquist, John T. Wilkins, Richard T. D’Aquila, Brian Mustanski, Elizabeth M. McNally
Usage data is cumulative from January 2025 through January 2026.
| Usage | JCI | PMC |
|---|---|---|
| Text version | 678 | 55 |
| 193 | 3 | |
| Figure | 281 | 11 |
| Table | 127 | 0 |
| Supplemental data | 96 | 0 |
| Citation downloads | 100 | 0 |
| Totals | 1,475 | 69 |
| Total Views | 1,544 | |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.
