New Omicron Variants Have Mastered Immune Evasion: Experts

Epidemiologists and virologists are watching closely as cases in South Africa rise sharply again, just five months after the Omicron variant caused a dramatic surge.

Photo Insert: The new strains didn’t have much of an impact initially, but over the past few weeks case numbers in South Africa jumped from roughly 1,000 per day on April 17 to nearly 10,000 on May 7.

This time, the drivers are two new subvariants of Omicron named BA.4 and BA.5, which the Network for Genomic Surveillance in South Africa detected in January 2022, Gretchen Vogel reported for Science.

The new strains didn’t have much of an impact initially, but over the past few weeks case numbers in South Africa jumped from roughly 1,000 per day on April 17 to nearly 10,000 on May 7. A third subvariant called BA.2.12.1 is spreading in the United States, driving increases along the East Coast.

It’s still unclear whether the new subvariants will cause another global COVID-19 wave. But like the earlier versions of Omicron, they have a remarkable ability to evade immunity from vaccines, previous infection, or both—a disturbing portent for the future of the pandemic and a potentially serious complication for vaccine developers. In most cases, vaccination or earlier infection still seem to provide protection from severe disease.

“There’s no reason to freak out,” says John Moore, an immunologist at Weill Cornell Medicine. The new strains are “an additional hassle,” he says, but “there’s no indication that they’re more dangerous or more pathogenic.”

Hospitalizations in South Africa, for example, have increased, “but because it is starting from a very low level, it’s not cause for alarm,” says virologist Tulio de Oliveira of Stellenbosch University, who helped identify BA.4 and BA.5.

Numbers of patients in intensive care units are as low as they have been since the start of the pandemic, he says.

“At the moment, we expect something similar to the Omicron BA.1 wave,” when hospitalization rates stayed manageable. The new superspreaders do, however, showcase the restless virus’ ability to find ways around the “immunity wall” built up over the past two years and to continue to circulate at high levels.

Even if the new variants cause relatively little severe disease, “it’s a numbers game,” says Leif Erik Sander, an infectious disease expert at the Charité University Hospital in Berlin; enough new infections could still overwhelm health systems.

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