Thousands of Amazon workers received the wrong Coronavirus test results after a mistake meant they were given inaccurate information by test and trace. The Guardian understands that 3,853 staff members at the online retailer received an erroneous result. Officials said they had tested negatively but received notifications to say they had tested positive and asking them to self-isolate. The Department of Health and Social Care (DHSC) said it had been resolved in a day but those working for the “world-beating” service that tracks down those who may have been infected with the virus said they were still dealing with the fallout. One test-and-trace worker said: “The tests, as far I can tell were good, but what people were told about their results is wrong.” The test-and-trace programme has been criticised since its launch. The government’s £22bn programme came under increasing strain during the height of the pandemic as it had to contact nearly triple the number of infected people. It not clear how these errors occurred but separately some test-and-trace healthcare professionals have expressed increasing concerns about the use of outsourced, inexperienced, call-centre staff to carry out the role of clinically trained staff. They are often employed on minimum wage by telesales businesses contracted by Serco, which has been drafted in to carry out detailed interviews with coronavirus patients. Amazon has a workplace testing programme, using PCR testing that was rolled out in autumn 2020. It has hired lab technicians and conducts tens of thousands of tests a day across hundreds of its sites worldwide. Amazon said all those who received the erroneous message from test and trace went home, on a precautionary basis. It added that it investigated and updated them shortly afterwards to confirm the message had been an error and they were not required to self-isolate. The government’s Scientific Advisory Group for Emergencies (Sage) has said that 80% of an infected person’s close contacts must be told to self-isolate within 48 to 72 hours for the national programme to be effective, so any delay risks allowing coronavirus to spread. Amazon reports cases to Public Health England on a daily basis. The government body then manages the onward transfer to test and trace, as well as the relevant bodies in the devolved nations where staff are based in Scotland, Wales or Northern Ireland. A DHSC spokesperson said: “NHS test and trace has the capacity to process over 700,000 tests a day from more than 800 test centres and mobile units, with the vast majority of people reporting no issues with the process. “On Saturday, some Amazon staff members who tested negative for Covid-19 received notifications from NHS test and trace to say they have tested positive and asking them to self-isolate. Working closely with Amazon, NHS test and trace rapidly notified affected employees to let them know they did not need to isolate.” A spokesman for Amazon said: “We’ve communicated with our associates and partners to support them with the appropriate action steps, as instructed by the NHS.”