This technology is meant to be used by local health agencies like city or county. If you have the app provided by the county and you are tested positive by them

This technology is meant to be used by local health agencies like city or county. If you have the app provided by the county and you are tested positive by them, they would then ask you if you would like to share that information with others. So the chance of DOS is nil since you actually have to test positive to broadcast the keys.