Throughout the hard-hit states of the Upper Midwest and northern Plains — in Illinois, Wisconsin, Iowa, Minnesota, Montana, Wyoming and the Dakotas — coronavirus case counts have been falling for weeks.
Could this be a sign that America’s worst surge to date has already peaked in the places it struck hardest — and a clue that the rest of the country might not be far behind?
It’s a critical question whose answer will help determine the trajectory of the U.S. pandemic, but we can only answer it if we know why infections have been falling there. And that’s far from obvious.
When case counts were skyrocketing across the Upper Midwest earlier this fall, the national media was all over the story. But the near simultaneous regional turnaround that began in mid-November has attracted a lot less attention.
Part of that may have been a reluctance to find silver linings in states where infection rates still rank among the highest in the nation (even if they’re slowing down) and where hospitalizations and deaths, which lag cases by weeks, still haven’t peaked. If South Dakota were a country, for instance, it would have the world’s highest per capita death rate over the last seven days (2.5 per 100,000 residents); the next closest countries would be Slovenia (2.4), Bulgaria (1.9) and Hungary (1.7).
Another reason the press hasn’t been publicizing the Upper Midwest’s progress may be prudence. As one New York Times blog post asked, “Will it last?” The concern is that falling positivity rates are not only temporary but illusory: the result of residents without symptoms rushing to get tested so they could celebrate Thanksgiving, thus momentarily reducing the percentage of tests coming back positive before risky holiday gatherings inevitably raised them again.
But now, two weeks later — long enough for holiday transmission to start to register in official tallies — there has been no regional post-Thanksgiving spike to speak of.
To be sure, a slowdown in reporting over the holiday briefly reduced the daily case counts, and a backlog last week briefly inflated them, producing some fluctuations in the curve. But the big picture is that since Thanksgiving, the average number of new daily cases has fallen by 19 percent in Illinois; 22 percent in South Dakota; 23 percent in Minnesota; 25 percent in Wisconsin; 27 percent in Montana; 38 percent in Wyoming; 41 percent in Iowa; and 48 percent in North Dakota.
In fact, there’s just one other state (New Mexico) where new cases are currently going down, according to the New York Times. Everywhere else (except Hawaii), cases are staying high.
This looks like real improvement, and for the most part, it stands up to scrutiny. Although none of these Upper Midwestern states are testing as many people now as they were before Thanksgiving, the percentage of tests coming back positive also appears to be down over the last two weeks — save for one possibly revealing exception. More on that in a minute.
The key question, again, is why.
There are two possible causes. One is behavior (and, by extension, policy). The virus has surged twice before in the U.S.: first in the Northeast, mostly, then across the Sun Belt last summer. Both times, cases peaked three or four weeks after they started to rise; they bottomed out about six weeks later. And both times, behavior was the main driver of that bottoming out: more caution, more distancing and more masks, whether due to spring’s lockdowns or summer’s less draconian interventions (and individual decisions).
Likewise, behavior is almost certainly the biggest factor in the Upper Midwest’s continued gains. Recent studies have found that 80 percent of people obey mask mandates once they’re instituted, regardless of whether they’re enforced; as a result, such mandates can reduce the spread of COVID-19 by more than 40 percent in three weeks. After resisting statewide mandates for months, the governors of Iowa, North Dakota and Montana all reversed course in mid-November, and their new orders are undoubtedly helping.
Elsewhere, the region’s chilling explosion in cases — not to mention its overwhelming hospitalization rates and record-breaking deaths tolls, which, again, are still rising today — probably convinced residents who had long dismissed the virus as a distant threat to finally start protecting themselves.
The fact that these shifts seem to be working in the Upper Midwest is especially encouraging for the rest of America. For one thing, the states where COVID-19 cases are now falling also happen to be some of the coldest in the country. If one of the major worries about the current surge is that it’s a factor of freezing weather and indoor holiday gatherings, turning the tide in the Upper Midwest shows the calendar doesn’t have to be destiny. If North Dakota can do it right now, anyone can.
The other heartening factor is political. Most of the states with improving case counts are deep-red states, or at least states with staunch conservative resistance to pandemic restrictions, like Wisconsin. And while most of them failed to prevent their outbreaks from getting really bad before reining things in, they had to overcome their residents’ skepticism in the process. In fact, they may have been some of the least cooperative places in the country in terms of taking COVID-19 precautions. Hopefully the coming peaks in less reluctant states will prove less devastating.
Beyond behavior, though, it’s worth pondering whether a second element — one that accounts for some of the resistance noted above — might be contributing to the downturn in cases across the Upper Midwest: the fact that a sizable share of the people who live in these less populated, less cautious states have already been infected with COVID-19.
According to Youyang Gu, an independent data scientist trained at the Massachusetts Institute of Technology who models cumulative state-by-state infections rates at covid19-projections.com, a full 37.4 percent of South Dakotans had probably contracted COVID-19 as of Nov. 25. In North Dakota, that number is 33.9 percent. In Wisconsin, it’s 26.5 percent. In Iowa, it’s 25.6 percent. In Montana, it’s 23.1 percent. In Illinois, it’s 23 percent. In Wyoming, it’s 21.6 percent. In Minnesota, it’s 21.1 percent.
According to Gu, those numbers are all significantly higher than the total fraction of Americans infected nationwide (17.3 percent) — and either equivalent to or higher than the total proportion infected in New York (23.2 percent), where the virus initially spread unchecked and has killed nearly 35,000 people, more than in any other state.
Given variations in exposure and individual preventative measures during a pandemic, some experts think spread of the coronavirus could drop drastically once between 35 and 45 percent of a given population has been infected; some have even theorized that a threshold as low as 20 percent could have a similar effect under the right conditions.
This isn’t the same thing as the much-debated herd immunity, which by most calculations requires that about 70 percent of a given population be inoculated (by infection or vaccination) to stop the spread of an epidemic.
But the steep and simultaneous decline in cases across the region raises an intriguing question: Is it possible that the virus rapidly infected a large percentage of the low-hanging fruit there — the many people who refused to take precautions, along with those whose working or living conditions made it especially tough to protect themselves — and is now having a harder time reaching the rest of the population?
South Dakota could be the exception that proves the rule. Alone among the states where cases are falling, the home of Mt. Rushmore has refused to institute a statewide mask mandate — or any serious statewide restrictions at all. And perhaps as a result it is also the only state of the bunch where the percentage of tests coming back positive has been steadily rising since Thanksgiving: from 42.4 percent to nearly 50 percent today.
Given that the state is conducting about 30 percent fewer tests now than it was then, this suggests that its declining post-Thanksgiving case count could, in fact, be a mirage. The more low-hanging fruit you offer the virus, the more tenuous any improvements will be.
Either way, the idea that at least some of the Upper Midwest’s progress could stem from the pervasiveness of the virus in the region underscores the tragic price these states are continuing to pay in sickness and death — and presents a warning to more populous states where the current wave has yet to crest.
In California, for example, new daily cases are up 90 percent over the last two weeks. New hospitalizations are up 77 percent. And new daily deaths are up 99 percent. But according to Gu’s estimates, just 11.8 percent of Californians had been infected with COVID-19 as of Nov. 25.
In the Upper Midwest, where many people live far apart and weren’t taking precautions until recently, it looks like a little may go a long way. In California, where most people live closer together and where restrictions are nothing new, a little isn’t going to be enough.
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