Contact tracing (contact investigation, etc.) is a standard practice in public health. In tuberculosis control where I got my start, it's what we do for any active case of TB we identify - we find the people who may have been exposed and widen the circle as necessary. It's also critical for STDs.
The only difference with COVID was the scale, not the methodology. There is an argument that if the disease is everywhere, people can be infected anywhere, and you would need an accordingly exponential increase in monitoring scale to pull any kind of signal from the noise floor. But the principles work for any disease.
The only difference with COVID was the scale, not the methodology. There is an argument that if the disease is everywhere, people can be infected anywhere, and you would need an accordingly exponential increase in monitoring scale to pull any kind of signal from the noise floor. But the principles work for any disease.
source: TB control physician for 17 years