Coronavirus antibody tests are not consistently reliable: Study

Antibody tests that have been touted as the solution to ending the coronavirus lockdown and getting people back to work are not reliable, according to public health experts in the US.

Antibody tests are supposed to reveal whether a person has had a disease, in this case COVID-19. Governments in countries including Germany and Sweden have suggested that using antibody tests to determine whether people have already had coronavirus could be a path to easing lockdowns and returning to normality, based on the assumption that people who have already had the virus cannot catch it again – allowing them to leave the house and go back to work.

Read more: WHO was right to debunk coronavirus ‘immunity passports’: Experts

But experts in the US are now raising concerns about the quality of the coronavirus antibody tests now on the market, providing a potentially major flaw in the strategy.

Of the 14 different tests available on the market, only three delivered consistently reliable results, with most of them mistakenly signaling antibodies in people who did not have them, according to a new research conducted by a group of more than 50 scientists.

Although the research is yet to be peer-reviewed and is subject to revision, the findings are raising concern about the course of the pandemic. If people rely on these tests, they might believe themselves immune to the virus when they are not and put themselves in danger.

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The researchers led by Dr. Alexander Marson, an immunologist at the University of California and Patrick Hsu, a bioengineer at the University of California, analyzed 10 rapid tests that deliver a yes-no signal for antibodies, and two tests using a lab technique known as Elisa that indicate the amount of antibodies present and are generally considered to be more reliable.

Four of the tests produced false-positive rates ranging from 11-16 percent, while many of the rest hovered around 5 percent.

The four tests with the fewest false positives were made made by Sure Biotech, Wondfo Biotech, and two Eliza tests, the researchers said.

A test made by Bioperfectus detected antibodies in 100 percent of the infected samples, but only after three weeks of infection. “None of the tests did better than 80 percent until that time period, which was longer than expected,” said Hsu.

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“Those numbers are just unacceptable,” Scott Hensley, a microbiologist at the University of Pennsylvania told New York Times. “The tone of the paper is, ‘Look how good the tests are.’ But I look at these data, and I don’t really see that.”

“If your kit has a 3 percent false-positive, how do you interpret that? It’s basically impossible,” he said. “If your kit has 14 percent false positive, it’s useless,” he added.

However, Dr. Marson who is also an investigator in the Chan Zuckerberg Biohub, which partly funded the study, feels there are some reasons for optimism.

“There are multiple tests that look reasonable and promising,” he said.