This is a summary, written by members of the CITF Secretariat, of:

Lin Y-CJ, Evans DH, Robbins NF, Orjuela G, Hu Q, Samson R, Abe KT, Rathod B, Colwill K, Gingras AC, Tuite A, Yi QL, O’Brien SF, Drews SJ. Utilization of the Abbott SARS-CoV-2 IgG II Quant Assay To Identify High-Titer Anti-SARS-CoV-2 Neutralizing Plasma against Wild-Type and Variant SARS-CoV-2 Viruses. Microbiology Spectrum. 0(0):e02811-22. doi:

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A new study, published in Microbiology Spectrum from the CITF-funded Canadian Blood Services (CBS) team led by Drs. Sheila O’Brien and Steven Drews, characterizes the ability of a new immunoassay to specify the concentration of neutralizing antibodies against SARS-CoV-2 in blood plasma.

COVID-19 convalescent plasma (CCP) is blood plasma collected from patients recovered from a SARS-CoV-2 infection and may be used to treat hospitalized patients with an early-stage COVID-19 disease or those who are immunocompromised. There is a need to estimate the amount of neutralizing antibodies in blood plasma to measure the potential effectiveness of CCP.

Researchers from Canadian Blood Services have authored several articles in which they used serological testing to characterize the levels of neutralizing antibodies in blood plasma. Here, they determine that the Abbott Quant assay, a chemiluminescent immunoassayImmunoassays are methods used to quantify antigens based on their reaction with an antibody. Chemiluminescence immunoassays use luminescent substances as markers attached to the antigen or antibody. This way, the antigen-antibody complex can be detected by light emission. designed to detect IgG antibodies directed against the receptor binding domain (RBD), is able to identify high- and low- titer plasma for the original SARS-CoV-2 virus and the Alpha, Beta, Gamma, and Delta variants. Further clinical trials are still needed to prove that CCP improves outcomes for patients with impaired immune systems.

Next steps include evaluating the ability of the Abbott Quant assay to quantitatively detect high-titer plasma against the Omicron variant.