“The issue with data is one can manipulate it to show anything you want if you have an agenda,” says YouYang Gu, an independent data scientist. Cherry picking is easy — prediction is much harder, and Gu is getting some attention for the fact that models he’s been creating since April actually forecast what’s happened with the spread of the disease in the U.S.
He 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.
That’s not to say that individual behavior doesn’t matter a lot — and the cancellation of big gatherings and other potential super-spreading events is more important than ever — but there may be more factors than we know driving the bigger picture.
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. (So far, antibody tests show only some 10-20% of the U.S. population has had the disease.)
The term herd immunity is a little vague in this context. It was created to characterize the impact of immunization. It refers to the percentage of the population that must get immunized in order for a pathogen to die out — a quantity that depends on the nature of the virus, the efficacy of the vaccine and the behavior of the hosts. If natural immunity is starting to help in some places, that would suggest herd immunity is a reasonable and worthy goal of an immunization program.