Too many corners are being cut in the race to find a Covid-19 antibody test | Jon Deeks

Despite optimistic coverage, the results from a new test seem too good to be true

• Report: Claims of 99% accuracy for UK Covid antibody test cannot be trusted'
• Coronavirus - latest updates

During the pandemic, Covid-19 tests have provided a rich source of media coverage. Most of us now know a bit about how these tests work, and that they can generate errors that lead to wrong and harmful decisions. Tests have to be used on the right samples at the right time, else more errors can be made, and there are important differences between have I got it?" viral swab tests, and have I had it?" antibody blood tests.

Despite this, the government keeps getting testing - particularly antibody tests - wrong. In March, the UK bought two million unproven finger-prick tests from China, which Boris Johnson described as having the potential to be a total game-changer". In April, an Oxford study reported that the tests were too inaccurate for public use. In May, a new laboratory antibody test manufactured by Roche was widely reported as 100% accurate" but Public Health England showed that the test failed to identify 16% of samples from people who had Covid-19. By then, the government had signed a contract to make the Roche test initially available to NHS and care workers. And in June, many public sales of laboratory antibody tests were stopped after the Medicines and Healthcare products Regulatory Agency (MHRA) found they were using finger-prick samples rather than the larger venous blood samples that were required.