Accuracy of commercial antibody kits for SARS-CoV-2 varies widely

Date:
September 24, 2020
Source:
PLOS
Summary:
There is wide variation in the performance of commercial kits for
detecting antibodies against severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2), according to a new study.



FULL STORY ========================================================================== There is wide variation in the performance of commercial kits
for detecting antibodies against severe acute respiratory syndrome
coronavirus 2 (SARS-CoV- 2), according to a study published September 24
in the open-access journal PLOS Pathogens by Jonathan Edgeworth and Blair Merrick of Guy's and St Thomas' NHS Foundation Trust, Suzanne Pickering
and Katie Doores of King's College London, and colleagues. As noted
by the authors, the rigorous comparison of antibody testing platforms
will inform the deployment of point-of-care technologies in healthcare
settings and their use in monitoring SARS-CoV-2 infections.


========================================================================== Throat and nose swab tests for SARS-CoV-2 establish if someone is infected
with the virus that causes coronavirus disease 2019 (COVID-19). These
tests are highly sensitive -- capable of detecting very low viral RNA
levels -- and are optimal for the early detection of the virus. The
performance of these tests depends on the time the sample is collected,
with viral load declining after the first week of symptoms. By contrast, antibody tests can determine whether someone has had the virus in the
past. For diagnosis later in disease, or in delayed-onset syndromes,
antibody tests could form an important part of hospital diagnostic capabilities. In the new study, the researchers developed their own
sensitive and specific antibody assay and used it to conduct unbiased, head-to-head comparisons of ten commercial antibody test kits on an
identical panel of 110 SARS-CoV-2-positive blood samples from patients
admitted to hospitals with COVID-19 and 50 pre-pandemic negatives.

There was a broad range of performance among the tests, with specificity
-- the ability of the test to correctly identify those without the disease (true negative rate) -- ranging from 82% to 100%, and overall sensitivity
-- the ability of a test to correctly identify those with the disease
(true positive rate) -- ranging from 60.9% to 87.3%. But all gave the
best results when used 20 days or more after the start of symptoms, with
most tests reaching a sensitivity value greater than 95%. In addition,
antibody levels were higher in individuals with severe illness compared
to those with asymptomatic or mild disease. When all commercial tests
were compared, lateral flow immunoassays called Accu-Tell, SureScreen
and Spring demonstrated highest sensitivity at earlier time points,
while maintaining specificities of 98% or above. Such lateral flow
immunoassays are affordable, quick and easy to use, and if they are
deployed appropriately, could have considerable usefulness in healthcare settings.

Co-author Jonathan Edgeworth notes, "We found that some of the quick
single-use kits (LFIAs) are as accurate as our sophisticated laboratory technologies.

Encouraged by these findings we are piloting LFIAs in the hospital to
give doctors a quick reliable answer in a range of clinical settings."

========================================================================== Story Source: Materials provided by PLOS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Suzanne Pickering, Gilberto Betancor, Rui Pedro Gala~o, Blair
Merrick,
Adrian W. Signell, Harry D. Wilson, Mark Tan Kia Ik, Jeffrey Seow,
Carl Graham, Sam Acors, Neophytos Kouphou, Kathryn J. A. Steel,
Oliver Hemmings, Amita Patel, Gaia Nebbia, Sam Douthwaite,
Lorcan O'Connell, Jakub Luptak, Laura E. McCoy, Philip Brouwer,
Marit J. van Gils, Rogier W. Sanders, Rocio Martinez Nunez,
Karen Bisnauthsing, Geraldine O'Hara, Eithne MacMahon, Rahul
Batra, Michael H. Malim, Stuart J. D. Neil, Katie J. Doores,
Jonathan D. Edgeworth. Comparative assessment of multiple COVID-19
serological technologies supports continued evaluation of point-
of-care lateral flow assays in hospital and community healthcare
settings. PLOS Pathogens, 2020; 16 (9): e1008817 DOI: 10.1371/
journal.ppat.1008817 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200924141549.htm

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