Covid-19 diagnostic kits

Very unevenly — and not fast enough in many countries. Although there is no official centralised database, Find has collated data that indicates a cumulative total of more than 4.9m tests had been carried out worldwide by March 29. But that figure excludes China because the group could only obtain reliable data for one Chinese province. South Korea, the country that got going first with extensive covid-19 diagnostic kits, has so far carried out 394,000 (equivalent to 770 per 100,000 people). Iceland has done 4,160 tests per 100,000.

it is not easy to quickly and massively ramp up testing capacity when it requires both high-quality covid-19 testing kits and properly trained staff

Andrew Preston, University of Bath

The US was very slow to get started, because the CDC’s first test did not work well, so it had to go back to the drawing board to create a new one. It was then slow to allow other labs to test for Covid-19. But over the past two weeks US has ramped up testing rapidly. Among larger European countries, the champion seems to be Germany, where public health officials have estimated that laboratories are carrying out as many as 500,000 coronavirus tests a week. Though official data has yet to confirm that number, it suggests that testing capacity has expanded fast in recent weeks. Germany’s decentralised test and laboratory infrastructure means the work is carried out not just in hospitals and doctors’ practices but also in special drive-in stations. Manufacturers are ready to supply the world with many millions of antibody tests, but health authorities and regulators are still evaluating their accuracy before allowing them to be rolled out widely. Last week Matt Hancock, UK health secretary, announced that the country had ordered 3.5m antibody test kits from various manufacturers.

HOW RELIABLE ARE THE COVID-19 RAPID TESTS?

The PCR test is extremely accurate when carried out carefully by experienced technicians in a well-equipped lab. Because it specifically detects genes found only in the Sars-CoV-2 virus, it will produce very few false positives, said Andrew Preston, reader in microbial pathogenesis at the University of Bath. False negatives — which indicate wrongly that someone is clear of infection — are more of a problem. They often result from problems with collecting and processing patient samples. For other viruses, false negative rates of 10 per cent are widely accepted and they can reach as high as 30 per cent. Therefore PCR tests “have more often been used to confirm an infection rather than give someone the all clear”, said Dr Gill at Warwick Medical School.
covid-19 diagnostic kits will not be known until they have been validated and technicians have gained more operating experience. Spain’s ministry of health last week withdrew 8,000 Chinese-made testing kits delivered to Madrid’s regional government because of worries about inaccurate results. But the manufacturer Shenzhen Bioeasy said the problems may have been because of incorrect sample collection or use of the product.

“It is not easy to quickly and massively ramp up testing capacity when it requires both high-quality kits and properly trained staff.”