The key to breaking the chain of transmission is isolation and quarantine of contacts. Testing will only prevent onward transmission if it's linked to these interventions & resources are provided to make them feasible. Otherwise, it will only serve as surveillance data. https://twitter.com/LancetMicrobe/status/1336255474249904130

How will a diagnosis help if your living situation doesn’t allow for isolation, you have a job that can’t be done from home, your work doesn’t provide paid sick leave, and your family depends on your income to meet basic needs or your access to care is linked to employment?

That's why we need supported isolation, an extra layer of protection for disadvantaged communities and investment of resources where they are most needed. Smart technologies are only smart when they have public health benefit and address people's needs. ( https://theconversation.com/covid-19-when-are-you-most-infectious-150760\\)