The “silent transmission” of covid-19 means people without symptoms could be a major source of its spread. How effective are masks as a defence? Plus, Kenneth Cukier asks Ivan Oransky, co-founder of Retractionwatch.com, whether the race to uncover the mysteries of the virus could lead to a torrent of “bad science”.

For more on the pandemic, see The Economist's coronavirus hub.

And please subscribe to The Economist for full access to print, digital and audio editions:

www.economist.com/radiooffer

Hosted on Acast. See acast.com/privacy for more information.