The Omicron variant of coronavirus surprised many Britons in recent weeks by turning up at parties undetected by rapid Covid-19 tests, prompting questions about whether the devices provide true confidence for people to live without fear of infection.
The UK Health Security Agency has said initial investigations show the rapid tests work just as well against Omicron as against Delta, the previously dominant strain. Experts believe the UK tests are likely to continue to work because they detect a different protein from the much-mutated spike — and the variant’s potentially far higher viral load means they could even be more effective.
But rapid lateral flow tests have always been imperfect, detecting an average of 72 per cent of symptomatic cases, and 58 per cent of asymptomatic ones, according to a meta-analysis of studies by the medical database the Cochrane Library.