There’s still so much we don’t get about Covid spread

As much as I like to think I know about Covid, I still embrace how much we just don’t understand.  And why we have learned so much about transmission (especially the role of aerosols, ventilation, etc.) when we look at the overall patterns of Covid surge and decline and the role of human behavior, there’s really so much we still have but a weak grasp on.  Thus, I really enjoyed the summary from Leonhardt about the thing we still don’t really understand:

In the case of Covid, the fable we tell ourselves is that our day-to-day behavior dictates the course of the pandemic. When we are good — by staying socially distant and wearing our masks — cases are supposed to fall. When we are bad — by eating in restaurants, hanging out with friends and going to a theater or football game — cases are supposed to rise.

The idea is especially alluring to anybody making an effort to be careful and feeling frustrated that so many other Americans seem blasé. After all, the Covid fable does have an some truth to it. Social distancing and masking do reduce the spread of the virus. They just are not as powerful as people often imagine.

The main determinants of Covid’s spread (other than vaccines, which are extremely effective) remain mysterious. Some activities that seem dangerous, like in-person school or crowded outdoor gatherings, may not always be. As unsatisfying as it is, we do not know why cases have recently plunged. The decline is consistent with the fact that Covid surges often last for about two months before receding, but that’s merely a description of the data, not a causal explanation.

“We still are really in the cave ages in terms of understanding how viruses emerge, how they spread, how they start and stop, why they do what they do,” Michael Osterholm, an epidemiologist at the University of Minnesota, has told me.

In coming weeks and months, it is possible that the virus will surge again, maybe because of a new variant or because vaccine immunity will wane. It is also possible that the population has built up enough immunity — from both vaccines and previous infections — that Delta will have been the last major wave.

We don’t know, and we do not have to pretend otherwise. We do not have to treat Covid as a facile referendum on virtue.

When caseloads are high, it makes sense to take precautions, even if we can’t be sure how much they matter. When caseloads are lower, it makes sense to take fewer, because almost every precaution has a cost. Other than that, the best we can do is get vaccinated and, as Osterholm says, stay humble.

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