Commercial SARS-CoV-2 antibody testing kits have a wide variation in sensitivity and specificity, according to a U.K. study published September 24 in PLOS Pathogens.
Researchers from Guy's and St. Thomas' National Health Service (NHS) Foundation Trust and King's College London developed their own sensitive and specific SARS-CoV-2 antibody test. They then used it to perform head-to-head comparisons of 10 commercial antibody test kits on an identical panel of 110 SARS-CoV-2-positive blood samples from patients admitted to hospitals with COVID-19, as well as 50 prepandemic negatives.
Specificity ranged from 82% to 100%, while sensitivity ranged from 60.9% to 87.3%. However, all tests gave the best results when used 20 days or more after the start of symptoms, when most yielded more than 95% sensitivity, according to the researchers.
The study's co-first authors included Blair Merrick of Guy's and St. Thomas' NHS Foundation Trust, as well as Rui Pedro Galão, PhD; Gilberto Betancor, PhD; Adrian Signell; and Suzanne Pickering, PhD, of King's College London.
The researchers also found that individuals with severe illness had higher antibody levels than those who were asymptomatic or had mild disease. In other results, lateral flow immunoassays called Accu-Tell, SureScreen, and Spring yielded the highest sensitivity at earlier time points, while still maintaining 98% or higher specificity.
"We found that some of the quick single-use kits (LFIAs) are as accurate as our sophisticated laboratory technologies," said senior author Jonathan Edgeworth, PhD, of Guy's and St. Thomas' NHS Foundation Trust in a statement. "Encouraged by these findings we are piloting LFIAs in the hospital to give doctors a quick reliable answer in a range of clinical settings."