Once it's visible, you can start demarcating red and green zones, places with more and less virus. Then you let people in green zones out of lockdown.
Enormous societal investment in many different kinds of diagnosis is cheap relative to lockdown.
- digital diagnosis (risk based on social network signals)
- wearables
- forehead thermometer
- CT scan
- PCR
- sequencing
- serology (antibodies, after infection)
- People at border crossings
- People with symptoms
- People after recovery via serology tests
- People without symptoms in a given area at random
All of these give info on the viral "funnel"