Day 390: Herd Immunity

David Friedman suggests that we've already hit herd immunity, not from the rapid rate of vaccination but from the flood of holiday cases:

I have been looking at the number of new cases per day, both for Santa Clara County and for the U.S., and the pattern is striking. Over the past month, number of new cases per day in the U.S. has gone down by a factor of about 2.4, for the county by a factor of about 3.5. Death rates are also down, although by much less, but one would expect death rates to lag case rates by a few weeks. I don't think the explanation can be the weather, since it's still winter. I don't think it can be vaccination because there has not yet been enough of it to substantially affect the case rate.

He's pretty optimistic that this is the end, all vaccination aside.

Johnson & Johnson's one-shot vaccine has emergency FDA approval.

Massachusetts cases were up a third of a percentage point today.