Still, the shortage of testing does not seem to be the only reason that cases have not surged in the U.S. Trends in Covid hospitalizations typically lag case trends by only about a week. And hospitalizations have continued to fall in the U.S., to their lowest level in more than two years.
3. Just wait
Even if high levels of immunity have kept cases from rising so far, the effect may not be permanent. Remember: About 45 percent of Americans were infected with Omicron, which leaves about 55 percent who were not. While many of those 55 percent may have had an earlier version of Covid, immunity can wane over time.
The current moment might be one of those times when we’re asking why cases have not begun to rise right as they begin to rise. “It may be too early to see a signal,” Jennifer Nuzzo, a Brown University epidemiologist, told me.
4. Another mystery
Throughout the pandemic, Osterholm — the Minnesota epidemiologist — has lamented that many scientists, journalists and laypeople exaggerate how much we actually know about Covid. His favorite example: The Alpha variant swept through Michigan and Minnesota last year and then largely died out, without causing case increases in other parts of the U.S. Another example: BA.2 has recently become the dominant variant in India, South Africa and some other countries without causing a spike in cases.
When I called Osterholm yesterday to ask why cases had not surged over the past few weeks, he simply said: “I don’t know, and I don’t think anybody really knows.”
Of all the variants, only the original Omicron was so contagious that it spread around the world in predictable ways, he said. Other versions of the virus have surged and receded in mysterious ways, much as a forest fire can die out without burning down an entire forest.
The bottom line: Cases still seem likely to rise, perhaps significantly, in the U.S. soon. But a new wave looks less certain than it did a few weeks ago. Regardless, the steps that can save lives in coming months remain the same: more vaccine shots, including boosters; and greater awareness of available treatments that offer extra protection for the vulnerable.