Distorting the truth

George N in his Jan 4 letter claims that the results of a published study of mass screening in Wuhan “undermines the need for lockdowns”. His claim is not supported by the authors of the study.

The study found 300 asymptomatic cases of Covid-19 in a screening of around 10 million residents of Wuhan in late May, after the January-April lockdown, which was far more restrictive than most countries could contemplate. Tracing of those in close contact with these 300 cases found no infections.

George N and others have concluded that no asymptomatic case can be a source of infection and that therefore lockdowns are unnecessary.

This conclusion is rejected by, among others, Prof Fujian Song, of the Norwich Medical School of the University of East Anglia, who conducted the study in collaboration with the Huazhong University of Science and Technology in Wuhan.

The report notes that “no viable virus [was found] in the identified asymptomatic cases. This means that these people were not likely to infect anyone else”. This is attributed to control measures, including lockdown.

But Dr Song warns that the results must not be interpreted [thus]. The cases in Wuhan were “truly asymptomatic”, showing no signs of infection before or during the study. “But there is plenty of evidence elsewhere showing that people infected with Covid-19 may be temporarily asymptomatic and infectious before going on to develop symptoms.”

The results of a meta-analysis by statisticians from University of Florida, Gainesville, University of Washington, Seattle, and the Fred Hutchinson Cancer Research Center, Seattle have been subject to a similar misinterpretation by opponents of lockdowns.

It should be warned that the spread of misinformation about Covid-19 can be as dangerous as the virus itself when it misleads the public into potentially dangerous activities, such as ignoring lockdown restrictions.

ALEC BAMFORD