>> The primary thrust of contract tracing needs to be manual, as that is what has worked in countries (like South Korea) which suppressed large outbreaks.

This post didn't explain what that meant, so I was curious how they are doing things, here's a New Yorker article on what's happening there:

https://www.newyorker.com/news/news-desk/seouls-radical-expe...

Here's another good explanation of what some of the issues are:

https://www.lightbluetouchpaper.org/2020/04/12/contact-traci...

The problem of trolling seems important to solve.