Yahoo UK Scientists respond to criticisms over lateral flow tests
A group of scientists have responded to criticisms about rapid turnaround coronavirus tests, as they sought to dispel “factual errors” made by other experts. Some 14 professors and health leaders refuted claims made in an article published in the British Medical Journal (BMJ) which stated that a mass rollout of lateral flow tests in care homes, schools, communities and by “untrained people at home” could cause “serious harm”. This claim was rejected by scientists including Dr Susan Hopkins, chief medical adviser for NHS Test and Trace, and Professor Calum Semple, from the Scientific Advisory Group for Emergencies (Sage), as they stated that the BMJ article contained “factual errors and makes several unsubstantiated allegations and assertions”. In a written response, they said the authors of the article, including Jon Deeks, professor of biostatistics at the University of Birmingham, have “prejudged” lateral flow tests, adding: “They appear to have made up their minds that LFDs (lateral flow device) are dangerous and of no value and therefore should never be used.” While they acknowledged Prof Deeks role as lead researcher of the Cochrane Review of Covid-19 diagnostic tests, they said they were “surprised” that he considered himself “an expert in Covid-19 or public health activity”. They added: “The authors are not actively involved in the breadth and depth of activities needed to evaluate LFD uses properly.” They asserted that there was “persistent and continuing confusion” between lateral flow tests, which can give results in less than 30 minutes, and PCR tests which are assessed in a lab setting and can have a slow turnaround time. They said: “The authors treat PCR mathematically as a perfect gold standard of infectiousness when there is now substantial evidence that it is not.” Prof Deeks had previously said that lateral flow tests in a mass pilot scheme in Liverpool “missed 60% of the cases which would have been picked up by PCR”. But Professor Louise K
Reuters UK researchers say lateral flow tests detect the most infectious COVID cases
LONDON (Reuters) – Rapid lateral flow tests will likely identify the most infectious COVID-19 cases with higher viral loads despite concerns over the overall sensitivity of the tests, Oxford University researchers said on Thursday, as the British government eyes mass testing to ease the current lockdown. Along with the roll-out of COVID-19 vaccines, the government has cited widespread testing, including lateral flow tests, as a key part of its plans to re-open the economy. Concerns about the tests’ accuracy have led some to question the plan, however. Some scientists have sounded alarm at Prime Minister Boris Johnson’s plans, dubbed “Operation Moonshot”, saying mass coronavirus testing is likely to be ineffective and expensive. Lateral flow tests are less sensitive than PCR tests, which are considered the gold standard, but can return results in just half an hour. Lateral flow tests work best among those with higher viral loads – more virus detected in the nose and throat. Looking at data from more than a quarter of a million people who have taken part in England’s test and trace scheme, scientists found that the greater the viral load, the more infectious the person. Applying previous estimates of the sensitivity of four lateral flow devices to those findings, the researchers found that the tests would detect between 83.7% and 90.5% of cases leading to onward transmission. “We know that lateral flow tests are not perfect, but that doesn’t stop them being a game changer for helping to detect large numbers of infectious cases sufficiently rapidly to prevent further onward spread,” said Tim Peto, Professor of Medicine at the University of Oxford. The researchers said they could not ascertain most of those who had been infected asymptomatically, however, “which may contribute substantially to onward transmission.”