Accuracy of COVID-19 Antibody Tests Varies Widely

By Robert Preidt
HealthDay Reporter

THURSDAY, Sept. 24, 2020 (HealthDay News) — Wide variation exists in the accuracy of commercial testing kits that check for antibodies against the new coronavirus, researchers say.

Antibody tests can determine whether someone has had the virus in the past. For diagnosis at a later stage of illness or in cases of delayed-onset, antibody tests could also be an important part of hospital diagnosis, the study authors said in the new report.

For the study, the researchers developed their own antibody test. They then used it to compare the performance of 10 commercial antibody test kits on an identical panel of 110 positive blood samples from hospitalized COVID-19 patients, and 50 pre-pandemic coronavirus-negative blood samples.

The findings were published online Sept. 24 in the journal PLOS Pathogens.

“We found that some of the quick single-use kits are as accurate as our sophisticated laboratory technologies,” study co-author Jonathan Edgeworth said in a journal news release. He’s with Guy’s and St. Thomas’ NHS Foundation Trust in the United Kingdom.

There was a wide range of accuracy among the tests. Specificity — the ability to correctly identify those without the disease — ranged from 82% to 100%. Overall sensitivity — the ability to correctly identify those with the disease — ranged from 61% to 87%.

All of the tests gave the best results when used 20 days or more after the start of symptoms, with most tests achieving sensitivity value greater than 95%, the researchers said.

The investigators also found that antibody levels were higher in patients with severe illness than in those with mild or no symptoms.