Two of those new theories have begun circulating in recent weeks, somewhat on the fringe of conventional wisdom, and while neither seems as likely to be playing a determinative role in the pandemic’s recent slowdown as weather or social distancing, both probably bear mentioning — and scrutinizing. The first is that some aspects of the “super-spreader” dynamics of the disease, by which 20 percent or fewer of patients produce 80 percent of new cases, could produce a natural flattening of the curve. But this 20/80 rule is not novel to this novel coronavirus, indeed it reflects the way that most viruses replicate and spread. Generally speaking, super-spreading experts believe that while this heterogeneity of spread might help explain some of divergent coronavirus trajectories (i.e., why one viral line died out while another replicated exponentially, or why one region was hit much harder than others), it probably does not suggest anything about the future course of the disease (because there’s no reason to think that super-spreaders are concentrated more heavily among those who’ve gotten the disease first, though social-distancing policies can reduce how many others each carrier might infect when sick).
The second intriguing theory suggests that, perhaps, many people who don’t have COVID-19 antibodies may nevertheless be immune or at least resistant, thanks to their previous exposure to other coronaviruses. This is known as “cross-immunization” or “cross-reactivity” — and one recent paper suggests that between 40 and 60 percent of unexposed patients exhibit some signs of resistance to COVID-19, theoretically picked up from other antigens. That could prove quite a significant finding, if the percentages hold up and the disease resistance is meaningful. Presumably our understanding of each of these questions will become clearer in the next weeks and months, during which time the disease seems likely to remain quite stable — continuing to infect, sicken, and in some cases kill, but at levels comparable to those the country and its peers in Europe have already experienced, not dramatically higher ones. In other words, we may be in the range of where we are today, straddling or just below an R of one, for quite a while.
This means, among other things, that warm weather may have helped buy the country another opportunity to put forth an actual pandemic response — much like the initial one bought by Chinese lockdowns and extending from the first alarms in January through the real outbreak of epidemic in the U.S. in March, which was entirely wasted by the federal government.