Based on experience to date with testing asymptomatic people with a lateral flow device in Liverpool, Iain Buchan, professor of public health and clinical informatics at Liverpool University, who is leading the program in the city said, “There is an opportunity to target lateral flow test capacity at twice-weekly testing for those who have to go out to work.”
Similarly, Jose Vazquez-Boland, chair of infectious diseases at Edinburgh University medical school said mass, systematic, regular screening of the population, “is the only workable strategy to control the spread of this highly transmissible virus.”
The focus to date on testing only people showing symptoms has been “short-sighted,” addressing “the tip of the iceberg, rather than tackling the much wider submerged base of asymptomatic carriers responsible for the silent spread of the coronavirus,” said Vazquez-Boland.
James Gill of Warwick University Medical School agreed. Asymptomatic COVID-19 positive people are thought to be infectious for a shorter period of time, but “identifying and isolating such individuals will be a turning point, as we can hope and expect their identification to reduce new case trajectories,” he said.
Ranged against these views, Alexander Edwards, associate professor of biomedical technology in the school of pharmacy at Reading University, noted COVID-19 tests are designed, checked, and approved for symptomatic testing. “Manufacturers typically prove their products work by testing samples from symptomatic infected patients. The accuracy drops significantly when used with larger groups of symptomatic people,” he said.
Accuracy also often drops when used in the community, rather than administered by trained experts. “It’s not clear how community testing centers can even check how accurate their testing service is,” Edwards said.
One of the most scathing critics of using lateral flow tests for population screening is Jon Deeks, head of the biostatistics, evidence synthesis, and test evaluation research group at Birmingham University. He said the government’s plan to roll out mass testing, “brings a real risk that it will increase rather than decrease the spread of COVID.”
Deeks said negative test results lead people to relax and change their behavior. “With the Innova test this is false reassurance – there are reports that false negatives have led people to ignore symptoms, leading to disease spread,” he said.
This was echoed by Angela Raffle, consultant in public health at Bristol University Medical School. For her, the news of further rollout of lateral flow testing is “very worrying.” Any benefit from finding symptomless cases will be outweighed by the many more infectious cases that are missed. “Already, outbreaks are known to have occurred because people have been falsely reassured by a negative lateral flow test, leading them to attend work whilst having symptoms,” she said.