The accuracy of a rapid finger-prick antibody test for SARS-CoV-2, may be considerably lower than previously suggested, researchers say.
The results, published in the journal The BMJ, suggest that if 10 people of people given the test had previously been infected, around one in five positive test results would be false-positive results.
“These conclusions contrast with an earlier study suggesting that the test gives no false positive results,” said study authors from Imperial College London in the UK.
The findings suggest the test can deliver a sufficient degree of accuracy for surveillance studies of the population, but laboratory confirmation of positive results is likely to be needed if these tests are to be used to provide evidence of protection from the virus.
The AbC-19TM Rapid Test uses a drop of blood from a finger-prick to see if it’s likely that someone has previously been infected with SARS-CoV-2.
It gives results in 20 minutes, without the need to go to a laboratory. For the results, scientists tested blood samples in a laboratory from 2,847 key workers in England.
The researchers said that the lower figure of 84.7 percent is probably a more realistic estimate of test sensitivity in the real world, if people were to choose to take the test to find out their own previous infection status.
“This means that 15.3 per cent of people with a previous SARS-CoV-2 infection would be missed,” the authors noted.