The most encouraging news is that worldwide Covid illnesses have dropped more than 30 percent since late August. “This as good as the world has looked in many months,” Dr. Eric Topol of Scripps Research wrote on Twitter.

The recent declines are consistent with the viruses mysterious two-month cycle. Since late 2019, cases have frequently spiked for two months and then declined for two months. For example, in India, Britain, and Spain, the Delta variant drove a surge in cases lasting somewhere from one and a half to two and a half months.

Conventional explanations, like seasonality, social distancing, and masks, are clearly insufficient. The cycles occurred during different times of the year despite human behavior, baffling Epidemiologists.

Human behavior plays a role, but social distancing is not as critical as public discourse often believes. “We’ve ascribed far too much human authority over the virus,” as Michael Osterholm, an infectious disease expert at the University of Minnesota, told David Leonhardt of the New York Times.

Recent declines occurred as schools started and many businesses returned to regular services.

One popular hypothesis involves a combination of virus biology and human behavior, wrote Leonhardt. “Perhaps each virus variant is especially likely to infect some people but not others — and once many of the most vulnerable have been exposed, the virus recedes. And perhaps a variant needs about two months to circulate through an average-sized community.”