New US covid cases have fallen 61% from the early January peak. Cases continue to fall across all regions and states.
What had appeared to be a breakout by North Dakota was probably just some sort of data reporting issue. North Dakota shows every sign of rejoining the slow downward progress of the rest of the Midwest states.
There’s no evidence yet that herd immunity is playing a role in the rate of decrease across states.
Right now, the best explanation for the decline in U.S. cases is “seasonality”. Coronavirus cases rose for no particular reason, and now they are falling for no particular reason. It was just the coronavirus season. And now it’s the end of coronavirus season. Just like flu season every year. And that’s why it’s affecting all the states, more-or-less all the same, more-or-less at the same time.
That’s an unsatisfying explanation, because there’s no content to it. There’s no way to make it work any better. There’s no telling how long it will last. It’s just a fact of life.
It’s the epidemiological equivalent of “stuff happens”.
But if you look across the northern hemisphere, seasonality seems to be the only rational explanation. China aside, almost every cold-climate country currently experiencing winter is seeing a decline in new cases. In Post #986, I joking brought up the brought up the Anglo-Irish-Canadio-American-Norsko-Swedish conspiracy theory of the COVID-19 pandemic. But in truth, this last wave of the pandemic has been reasonably closely synchronized across half the planet.
The only significant exception I’ve found are France and Belgium, where the level of new cases is roughly constant. Everywhere else where it’s winter now, it looks like new case counts are declining.