A rather remarkable thing happened on Tuesday and Wednesday: My Twitter timeline and TikTok “For You” page proved to be a useful epidemiological barometer. It started as a trickle of anecdotal tweets. Wow, like half the people in my group chat have COVID. People began retweeting photos of COVID testing lines sprawling down sidewalks. By Wednesday, my TikTok page was an endless series of videos from total strangers that looked like this:

After a weekend of vaccinated and boosted holiday party-going and general life-living, the Omicron variant appears to have made solid landfall in major American cities, and things are moving quickly:
Um, we've never seen this before in #NYC.
— Jay Varma (@DrJayVarma) December 16, 2021
Test positivity doubling in three days
12/9 - 3.9%
12/10 - 4.2%
12/11 - 6.4%
12/12 - 7.8%
Note: Test % is only for PCR & NYC does more per capita daily than most places ~67K PCR/day + 19K [reported] antigen over past few days (1/2) pic.twitter.com/PhxsZq55jn
Very quickly:
The number of new cases reported statewide on Thursday alone — 18,276, more than 8,300 of them in New York City — appears to be the most new cases ever recorded in a single day for New York City, and was the highest total statewide since the winter surge last January.
— Sharon Otterman (@sharonNYT) December 16, 2021
A steep increase in cases was, of course, expected and follows trends from the United Kingdom and South Africa. Even so, the rise feels stark. The chart that stood out to me is this one, from Cornell University:
The O signature is a |@Cornell, graph by @AnilOza16 @cornellsun pic.twitter.com/4CNYCZcQSn
— Eric Topol (@EricTopol) December 15, 2021
What the chart doesn’t show is that 97 percent of Cornell students are vaccinated. As of Thursday, none of those cases featured severe illness. And because the school does comprehensive surveillance testing (including of asymptomatic students), it's likely that a number of those positives came from people who didn't know they had it. And so the situation feels a bit different than many of us are used to. Scary-looking hockey-stick graph. Almost all breakthrough infections. So far, reasonably mild illness. Changes in plans (exams are moving online), but no real panic.
This is where I’d like to remark that we are in a super-weird moment right now. This isn’t an earth-shattering observation, but I still think it’s worth acknowledging how, 20 months into this pandemic, we’re entering a new phase with different dynamics. Even the culture-warring around COVID is of a different flavor.