Not a re-infection. A flare up of the original infection as some people’s immune systems take weeks to build up the antibodies.
Your links refer to stories over 4 weeks old. I am referring to statements from leading scientists in the last few hours that demonstrate the re-infection scenario in that short a period of time is not possible. That info is from a private source (MD of one of the pharma giants). It will be public soon enough.

What would you say if I suggested over 1 million people here and over 7 million in the US have already had the virus without even knowing, and that number is doubling every 3 days, and there will be herd immunity in 3-4 weeks?
That can’t be proven (yet) but if the initial testing on health workers is true (only 1 in every 15-20 people) show symptoms then it could be.

Now just my opinion
The virus some time before the first reported Chinese case and was already being spread well before restrictions came in anywhere. Hence there were many more carriers than imagined, and it explains why there were many cases with no traceable contact to anyone else with symptoms.