[M T]

ANOTHER variable to consider is mutations or gene sequences of the virus. What it was in December might not be what it is in March. Perhaps this would provide some clues to re-infection. Then again, testing may not have been able to pick up trace levels of the virus in people who had it but were cleared. IOW, re-infection could be a misnomer, and the reality is it never really went away.

Sometimes the more you think you know, the more you realize how little you do. Seems to be the case with SARS-CoV-2.

The WHO-China joint mission investigated mutations to Feb 24.

The Joint Mission carried out whole gene sequencing in 104 new coronavirus strains isolated from different locations
and confirmed that the homology among these strains reached 99.9%. Accordingly, the Joint Mission believes that the virus has no obvious variation

You may find the phylogeny of 138 samples from around the world interesting.
https://www.gisaid.org/epiflu-applicatio...-cov2-app/
(This is a live display, you can get more info out of it.) 

The newest on that chart as I type is 27 Feb from Mexico. 
The Solano county individual is CA9 (top red one, Feb 23) (Highlight USA to see the US genomes), and is similar to a genome from Thailand from Jan 13. 
The genome from the Mountain View patient is not available.

The earlier posts about the Seattle cases (WA1 and WA2) were about that the genome of WA2 (bottom red one, Feb 24) is very similar to WA1 (Jan 19, red, just above WA2, middle of chart), suggesting that it is the same infection circulating 5 weeks later.

[M T]

ANOTHER variable to consider is mutations or gene sequences of the virus. What it was in December might not be what it is in March. Perhaps this would provide some clues to re-infection. Then again, testing may not have been able to pick up trace levels of the virus in people who had it but were cleared. IOW, re-infection could be a misnomer, and the reality is it never really went away.

Sometimes the more you think you know, the more you realize how little you do. Seems to be the case with SARS-CoV-2.

The WHO-China joint mission investigated mutations to Feb 24.

The Joint Mission carried out whole gene sequencing in 104 new coronavirus strains isolated from different locations
and confirmed that the homology among these strains reached 99.9%. Accordingly, the Joint Mission believes that the virus has no obvious variation

You may find the phylogeny of 138 samples from around the world interesting.
https://www.gisaid.org/epiflu-applicatio...-cov2-app/
(This is a live display, you can get more info out of it.) 

The newest on that chart as I type is 27 Feb from Mexico. 
The Solano county individual is CA9 (top red one, Feb 23) (Highlight USA to see the US genomes), and is similar to a genome from Thailand from Jan 13. 
The genome from the Mountain View patient is not available.

The earlier posts about the Seattle cases (WA1 and WA2) were about that the genome of WA2 (bottom red one, Feb 24) is very similar to WA1 (Jan 19, red, just above WA2, middle of chart), suggesting that it is the same infection circulating 5 weeks later.