Longitudinal SARS-CoV-2 antibody study using the Easy Check COVID-19 IgM/IgG™ lateral flow assay

PLoS One. 2021 Mar 4;16(3):e0247797. doi: 10.1371/journal.pone.0247797. eCollection 2021.

Abstract

Since the initial identification of the novel coronavirus SARS-CoV-2 in December of 2019, researchers have raced to understand its pathogenesis and begun devising vaccine and treatment strategies. An accurate understanding of the body's temporal immune response against SARS-CoV-2 is paramount to successful vaccine development and disease progression monitoring. To provide insight into the antibody response against SARS-CoV-2, plasma samples from 181 PCR-confirmed COVID-19 patients collected at various timepoints post-symptom onset (PSO) were tested for the presence of anti-SARS-CoV-2 IgM and IgG antibodies via lateral flow. Additionally, 21 donors were tracked over time to elucidate patient-specific immune responses. We found sustained levels of anti-SARS-CoV-2 antibodies past 130 days PSO, with 99% positivity observed at 31-60 days PSO. By 61-90 days PSO, the percentage of IgM-/IgG+ results were nearly equal to that of IgM+/IgG+ results, demonstrating a shift in the immune response with a decrease in IgM antibody levels. Results from this study not only provide evidence that the antibody response to COVID-19 can persist for over 4 months, but also demonstrates the ability of Easy Check™ to monitor seroconversion and antibody response of patients. Easy Check was sufficiently sensitive to detect antibodies in patient samples as early as 1-4 days PSO with 86% positivity observed at 5-7 days PSO. Further studies are required to determine the longevity and efficacy of anti-SARS-CoV-2 antibodies, and whether they are protective against re-infection.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Viral / blood*
  • Antibodies, Viral / immunology
  • COVID-19 / blood*
  • COVID-19 / immunology
  • COVID-19 Serological Testing / instrumentation
  • COVID-19 Serological Testing / methods
  • Equipment Design
  • Female
  • Humans
  • Immunoglobulin G / blood*
  • Immunoglobulin G / immunology
  • Immunoglobulin M / blood*
  • Immunoglobulin M / immunology
  • Longitudinal Studies
  • Male
  • Middle Aged
  • SARS-CoV-2 / immunology*
  • SARS-CoV-2 / isolation & purification
  • Young Adult

Substances

  • Antibodies, Viral
  • Immunoglobulin G
  • Immunoglobulin M

Grants and funding

The authors received no specific funding for this work.