Edit: Oh, no. My wife tells me this is prompting calls to ease up on the COVID-19 hygiene at William and Mary. I know it’s tough to grasp, but that arithmetic of epidemics says that would be unwise.
It’s too late this evening, but I’ll write up the math on that one tomorrow. Until the virus is no longer in circulation anywhere, the way you keep it from entering and spreading in the W&M student body is via the combination of vaccination and COVID-19 hygiene. I realize that “herd immunity” is rarely discussed this way, but it’s the combination of those two effects that reduces the transmission rate enough to get you over the herd immunity threshold.
You risk firing this right back up again if you drop the COVID-19 hygiene portion of this system, given the incidence of new cases in the community.
Original post follows:
Yesterday W&M reported zero new cases in 1488 tests. Today they reported zero new cases in a further 1599 tests.
Like so:
It’s extremely unlikely that we would observe this, if the recent rate of new infections was continuing. That’s what yesterday’s math showed.
Something has changed. And as I said yesterday, it boils down to two choices.
One option is that there’s some technical glitch in the testing. Either the lab is making mistakes, or W&M no longer reports positives until they are confirmed by a second test, or something. That is, maybe for some technical reason, we simply aren’t (yet) seeing any positives.
Doesn’t seem too likely, given that they’ve never done that before.
The other option is that, given the high known vaccination rate, and the good COVID-19 hygiene, the W&M student body has managed to hit herd immunity. Or something close to it. They successfully terminated most or all existing chains of infection within their ranks. For the time being.
To be clear, I’m not quibbling over the fact that this is good news. It’s just a question of exactly how good the news is. You’d just want to be a little cautious about declaring victory. So give it another day or two, and we should be absolutely sure of how good this news is.
But if I had to guess, I think we’re looking a herd immunity. We’re looking at a real-world demonstration that a high rate of vaccination combined with good COVID-19 hygiene can bring the pandemic to end. If so, that’s not just good news for William and Mary narrowly. For the U.S. more broadly, it’s one small light at the end of what has been a very long tunnel.
