Determined to avert another widespread lockdown when another coronavirus wave hit Vietnam in late July, the authorities have swung into action to contain the spread of the virus. Ditto their alacrity to enlist public participation in downloading Bluezone, a contact-tracing app designed to detect Covid-19 exposure.Rolled out in mid-April, Bluezone is among dozens of contact-tracing apps built globally to notify the public of any potential exposure.Once downloaded, thanks to GPS or Bluetooth…