Comparison of two assays to detect IgG antibodies to the receptor binding domain of SARS‑CoV‑2 as a surrogate marker for assessing neutralizing antibodies in COVID-19 patients

https://doi.org/10.1016/j.ijid.2021.06.031Get rights and content
Under a Creative Commons license
open access

Highlights

  • The haemagglutination test (HAT) detects the presence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

  • It detects antibodies that correlate with neutralizing activity.

  • The HAT is a very cheap assay, with high sensitivity and specificity.

Abstract

Background

Neutralizing antibodies (NAbs) are important for protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection. In this study, two assays that are correlated with NAbs were compared: the haemagglutination test (HAT) and the surrogate virus neutralization test (sVNT).

Methods

The specificity of the HAT was compared with the sVNT, and the sensitivity and persistence of antibodies in patients with varying severity of illness was assessed in a cohort of 71 patients at 4–6 weeks and 13–16 weeks. The kinetics were assessed in the first, second, and third weeks in patients with varying severity of acute illness.

Results

The specificity of the HAT was >99%, and sensitivity was similar to the sVNT. The levels of HAT were significantly and positively correlated with those of the sVNT (Spearman's r = 0.78, P < 0.0001). Patients with moderate and severe illness had higher HAT titres when compared to those with mild illness. Six of seven patients with severe illness had a titre of >1:640 during the second week of illness, whereas only five of 31 patients with a mild illness had a titre of >1:160 in the second week of illness.

Conclusions

Since the HAT is a simple and very cheap assay to perform, it would be ideal to use as an indicator of NAbs in resource-poor settings.

KEYWORDS

COVID-19
Disease severity
Haemagglutination assay
Surrogate neutralization assay
Neutralizing antibodies

Cited by (0)