One case of a person infected twice by different varieties of Covid-19 has now been demonstrated with certainty. Per second infection was asymptomatic; such cases can easily go undetected until the world sets up massive testing.

The virus has mutated into distinct strains while spreading massively. If all governments had jumped on it early, as a few Asian countries did, it would not have had a chance to mutate much. Thus, if the existence of different strains has some important consequences — for instance, if one vaccine doesn't do for all of them — that is also the fault of the bad choices many governments made starting in March and even February.

It is not conclusively ruled out that a person could be infected twice by the same strain.

Reading on a screen is not conducive to reading carefully — it encourages people to skim. Students may never learn to do the former.

A US government "development" organization is investing billions in fossil fuel projects.

Proposing a one-time special tax on the billionaires' 2020 windfall.

In general, I don't think we should limit their tax increases to one time, but I am in favor of this proposal.

The Army Corps of Engineers blocked the proposed Pebble Mine, demanding a plan to mitigate the damage that the mine would do. An adequate plan may be impossible, or may cost so much that the mine becomes unprofitable to start. Let's hope that the corps does not settle for an inadequate plan.