When the Next Covid Wave Breaks, the US Won’t Be Able to Spot It

Lines on charts can tell you something about the state of the Covid pandemic in the United States. Deaths: declining, even with the looming milestone of the millionth US death. Hospitalizations: at historically low levels, but ticking back up. Cases: rising, particularly in the Northeast, reliably a harbinger for the rest of the country.

What you can’t do with those lines is use them to map your way forward—because at this point, we’ve reached the choose-your-own-adventure stage of the pandemic. Most mask mandates have been lifted. Testing programs have been cut back, here and in other countries. Congress has declined to fund big chunks of the White House’s Covid agenda. Knowing where you are at risk is more confusing than ever, and likely to get more challenging as predicted new variants arrive.

All the indicators suggest the US is likely poised for a new surge of Covid; in some parts of the country, that surge may already be arriving. But in our zeal to declare the pandemic over, we may have maneuvered ourselves into a position where it is now harder to detect a coming wave. “More and more, the relaxation of public health requirements, mandates, has placed responsibility on the individual and the employer,” says Saskia Popescu, an infectious-disease epidemiologist and an assistant professor at George Mason University. “But I’ve noticed that when we relax these mandates, we’re doing that at times that are really inopportune, when case numbers are already increasing.”

And cases are increasing in the US. The seven-day moving average calculated by the US Centers for Disease Control and Prevention stood at 42,605 cases last week, which was 35 percent higher than one week earlier. The number of counties that score high and medium on the CDC’s “community levels” map both increased last week.

All of this is due to the Omicron variant that roared across the world last November, and even more to its fast-emerging sublineages. What most of us think of as Omicron is known scientifically as BA.1; that was supplanted in January by a newer version, BA.2. Omicron’s initial success and laser-fast spread were driven by its ability to work around the immune protections created by vaccination. Even though it triggered less-severe disease, it caused so many cases that it crushed hospitals. BA.2 did not leverage immune escape in the same manner BA.1 did, but it turned out to be more ferociously transmissible than its already-contagious predecessor. By mid-March, the World Health Organization reported that BA.2 had become the dominant strain worldwide.

Simultaneously, BA.3 emerged, then BA.4 and BA.5, rapidly displacing other variants in southern Africa and migrating to countries in Europe. Meanwhile, a variation on BA.2 with the technical designation BA.2.12.1 is surging as well. In a weekly assessment published Tuesday by the CDC, it now accounts for almost 29 percent of US cases.

These subvariants matter for two reasons: First, each is a sign that SARS-CoV-2 won’t be lifting its siege anytime soon. On Monday, evolutionary biologist Tom Wenseleers predicted “a significant wave every six months with significant mortality and morbidity.”