Sorry, but there's no government on earth, including China's, that's able to do reliable contact tracing of people potentially going to massive gatherings. Heck

Sorry, but there's no government on earth, including China's, that's able to do reliable contact tracing of people potentially going to massive gatherings. Heck, they don't even need to do that - have you ever been in the Shanghai Metro? You'll have "contact" with thousands of anonymous people if you just commute to work and back again. Trace that! The only thing I agree to is "it will take weeks for the disease to become out of control again". Yes, it will, and that is part of the problem - it'll be at least half a month until it's even possible for you to notice that you're getting the same problem all over again.