Last week the White House announced that President Joe Biden had tested positive for COVID-19, making him the most prominent example of this summer’s mini-surge.

Each summer, COVID-19 seems to catch people in the US off guard by defying our assumptions about how viruses ought to behave in warm weather. The flu, for example, typically goes underground until the winter holidays. But COVID-19 burbles back up to ruin our vacation plans and force us to offload summer concert tickets. Based on what researchers are seeing in wastewater, it’s happening again.

That’s likely something we just need to get used to. After several wild years, COVID is settling into a cadence that is driven less by the calendar and more by our waning immunity, changes to its genome and the right mix of conditions to allow it to thrive.

The only real good news is that we are far less vulnerable to COVID than we were in spring 2020. Consider that summer COVID-19 waves used to come onto our radar through news of crowded hospitals. Now, we catch wind of rising infections through text messages from friends and family or emails from colleagues noting they’re working from home for a few days. Or White House bulletins about the president.

The more diligent might be watching for a rise in the wastewater data, which in the absence of widespread clinical testing has become the most reliable way to assess the state of the outbreak in the US (Infected people shed virus in their poop and pee, which makes sewage a decent gauge of the health of a population.) And right now, swaths of the US wastewater map are brightly lit with high or very high levels of COVID-19 detected in the sewage, with the West Coast, Florida and Texas being particularly hard hit.

Why now? (Seriously, COVID: Why now?!) Since its emergence in 2019, COVID-19’s peaks and valleys have been idiosyncratic. Indeed, the Centers for Disease Control and Prevention earlier this month noted that the virus can surge at any time.

Like the flu, COVID-19 really takes off when the conditions that facilitate transmission become more favorable -- that is, in winter, when we’re largely huddled inside and the cold, dry conditions allow these viruses to linger longer on surfaces and in the air. But unlike the flu, COVID-19 also spreads in summer, when the heat drives us inside and we pack into airplanes and gather for summer holidays.

And there’s an additional factor creating COVID-19’s unsettled pattern, says Marc Lipsitch, an epidemiologist at the Harvard T.H. Chan School of Public Health. “That’s the appearance of new variants that are able to get by the immunity that many people have.”

The latest of those are the so-called “FLiRT” variants, a collection of Omicron relatives that include KP.3, KP.2 and LB.1. Since March, the three variants, which all contain similar mutations, have been crowding out cases caused by JN.1, which had driven a surge this past winter.

Their rapid emergence even prompted the Food and Drug Administration to switch up the recommended composition for the fall COVID-19 vaccines. Although the agency’s advisers in early June had settled on targeting JN.1, the agency has since shifted its focus to the KP.2 strain, which was estimated to be responsible for about a quarter of infections as of early July.

Still, a cadence does exist: A big winter surge and a smaller summer outbreak seem to be our new normal, with the caveat that new variants and waning immunity can bring other bumps in between.

“We’re starting to get to see the seasonal patterns more clearly,” says Michael Mina, an epidemiologist and expert on infectious disease outbreaks. “And seasonality doesn’t mean it has to be fall or winter -- it’s not baseball seasons. It means predictable.”

The silver lining is that our layers of immunity from vaccines and prior infections mean exposure to new variants has a lot less of an impact than it used to. The current summer wave, while supremely annoying, is causing far fewer serious infections. Hospitalizations have risen, but not nearly as sharply as in summers past.

We can thank the elephant-like memory of our immune cells for that. Although mutations are changing the virus, many parts of it remain recognizable to our immune system, Mina says. So we might not make the ideal antibodies to shut down an infection before it starts, but most of us by now are able to overcome the virus before it makes us sick enough to go to the hospital.

That doesn’t mean we should ignore COVID-19 -- or for that matter, forgo the new booster this fall. That’s especially true if you’re vulnerable to serious disease or it’s been a while since your last shot or infection. And long COVID-19, while becoming increasingly less common, continues to be a good reason to try to avoid this virus.

Still, we might want to moderate the language used to describe this summer bump. Any uptick in cases is worth paying attention to, but some of the superlatives being used for the current one might lead one to believe we’re back in a delta or omicron era. We are not.

Canceled plans and ruined trips are frustrating. But they’re a world away from overcrowded emergency rooms.

Lisa Jarvis

Lisa Jarvis is a Bloomberg Opinion columnist. The views expressed here are the writer’s own. -- Ed.

(Tribune Content Agency)