It might also explain why BA.5 is rising now.

That property-immune evasion-likely enabled BA.1 to oust Delta last winter.

Variants can spread rapidly without being any better at finding new hosts, as long as they’re better at slipping past those hosts’ immune defenses. But those calculations are “fully wrong,” Trevor Bedford, a virologist at the Fred Hutchinson Cancer Research Center, told me. Using that logic, buttressed by some back-of-the-envelope calculations, some commentators have claimed that BA.5 is as transmissible as measles, making it among the most contagious viral diseases in history. You might assume that a new variant gains dominance by being inherently more transmissible than its forerunners. (Most of this article will deal with BA.5 alone because it already seems to be outcompeting its cousin.) Hospitalizations have risen to their highest level since March. In the U.S., BA.5 now accounts for about 54 percent of all COVID infections, and BA.4, about another 17 percent. BA.4 and BA.5 are spreading even more quickly: First detected in South Africa in January and February, they have since displaced BA.2 all over the world, leading to surges in both cases and hospitalizations. BA.2 took over from BA.1, and caused a surge in the spring. That initial version of Omicron, now known as BA.1, was just the first of a mini-dynasty of related variants that have since competed against one another in a grim game of succession. The age of Omicron began shortly after Thanksgiving, as the new variant swept through the U.S., ousting its predecessor, Delta. “It’s not over, and we are playing with fire by letting this virus circulate at such intense levels.” “We will not prevent all transmission-that is not the goal-but we have to reduce the spread,” Maria Van Kerkhove, an infectious-disease epidemiologist at the World Health Organization, told me. Infections (and reinfections) still matter, and by increasing both, BA.5 is extending and deepening the pandemic’s ongoing burden. The new variant is not an apocalyptic menace.īut it can’t be ignored, either. Goldstein told me that he takes “some level of comfort” in the knowledge that, based on how other countries have fared against BA.5, vaccines are still keeping a lot of people out of hospitals, intensive-care units, and morgues. That doesn’t mean we’re about to have a surge on the scale of what we saw last winter, or that BA.5 (and its close cousin BA.4) will set us back to immunological square one. “People shouldn’t be surprised if they get infected, and they shouldn’t be surprised if it’s pretty unpleasant,” Stephen Goldstein, a virologist at the University of Utah, told me. Those who have managed to avoid the virus for close to three years will find it a little harder to continue that streak, and some who recently caught COVID are getting it again. The new variant is spreading quickly, likely because it snakes past some of the immune defenses acquired by vaccinated people, or those infected by earlier variants. Once more, the ever-changing coronavirus behind COVID-19 is assaulting the United States in a new guise-BA.5, an offshoot of the Omicron variant that devastated the most recent winter.

Faceless menace contents