Covid Spread Can’t Only Be Explained by Who’s Being ‘Bad’ | Bend Bulletin - Faye Flam, Bloomberg:
August 13, 2020 - "There are some weird things going on in the coronavirus data. It’s curious that cases dropped so fast, and have stayed pretty low, in the spring hot zones — New York, New Jersey and Connecticut. And why did cases remain so low in Idaho and Hawaii until recently?... This is the time to use scientific methods to understand what’s happening. The pandemic has gone on long enough to reveal patterns in the way it spreads. If it’s all about behavior, that’s a testable hypothesis. If, as a few speculate, dramatic drops in some places have something to do with growing immunity in the population, we can also turn that into a testable hypothesis....
"YouYang Gu, an independent data scientist ... recently took to Twitter to urge public health officials to apply scientific thinking. He pointed to data on Louisiana, where cases were rising earlier in the summer and seemed to level off after various counties issued mask mandates. But breaking the data down by county, he says, revealed a different story. Mask mandates varied in their timing, but places that implemented them late saw no more cases or deaths than those that did so early. 'I don’t think there’s currently enough evidence to support the fact that recent policy interventions (mask mandates, bar closures) were the main drivers behind the recent decrease in cases,' he wrote....
"A few scientists are examining the possibility that previously hard-hit areas are now being affected by a buildup of immunity, even if it flies in the face of the widespread understanding that the disease has to run through at least 60% of the population to achieve so-called herd immunity.... Scientists have started to investigate the possibility that there’s another critical factor here — heterogeneity in the way humans interact, and in our inherent, biological susceptibility.... In a Science paper published in June, University of Stockholm mathematician Tom Britton and colleagues calculated that herd immunity might be reached after as few as 43% of a very heterogenous population becomes infected. People mix unevenly in a way that could lead to little pockets of immunity, slowing the spread of the virus long before the world achieves herd immunity.
"We may also be heterogeneous in our biology. A recent paper in Science suggests that many people who’ve never been infected with SARS-CoV-2 carry a kind of immune cell, called a T-cell, which recognizes this novel virus and may partially mitigate an infection. These cells may be left over from infections with ... coronaviruses that cause the common cold.... Whatever the source of this heterogeneity, we know it exists. Most people on the contaminated cruise ship Diamond Princess remained uninfected, while others got asymptomatic infections and still others got severely ill.
"Those differences can inform disease models, says statistics professor Gabriela Gomes of the University of Strathclyde in Scotland. 'What we see is that infections do not occur at random, but that people who are most susceptible to infection get exposed first,' she says, leaving a pool of ever-less susceptible people behind. So far, her predictions of the spread in the U.K., Belgium, Spain and Portugal have aligned well with reality.
"Her models ... keep predicting declines after the infection [has] reached between 10% and 35% of the population. That doesn’t mean the virus has gone away — only that by her models, it won’t explode in those same places again. Gu’s models, too, predict no big second waves in New York City or Stockholm, but leave open the possibility of new outbreaks in relatively unaffected areas....
"[Gomes] says she didn’t expect to come up against resistance to her models in the scientific community. While she’s starting to get some attention in the media, she said journal editors told her that her modeling ideas, in preprint, posed the danger of making people feel entitled to relax their vigilance. Maybe the opposite is true, she suggests. Maybe censoring all but the most pessimistic views could discourage action by making the problem seem endless."
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