Is the ‘Stealth’ Version of Omicron Cause for Alarm?

MONDAY, Jan. 31, 2022

The so-called “stealth” variant of Omicron isn’t likely to cause another devastating wave of COVID-19, experts say.

The new version of the variant, called BA.2, doesn’t appear to cause more severe disease and vaccines are just as effective against it as against the original Omicron variant (BA.1), but BA.2 does show signs of spreading more rapidly.

“This may mean higher peak infections in places that have yet to peak, and a slowdown in the downward trends in places that have already experienced peak Omicron,” Thomas Peacock, a virologist at Imperial College London, told The New York Times.

Back in December, South African researchers discovered that a growing number of PCR tests were failing to detect the spike gene — a sign that BA.1 was becoming dominant.

Unlike BA.1., BA.2 lacks a key spike mutation. That can cause a PCR COVID detection test to fail. Without the ability to use PCR tests to track BA.2, some scientists nicknamed it the “stealth” version of Omicron, the Times reported.

But BA.2 wasn’t invisible: Researchers could still spot it by analyzing the genetic sequences of samples from positive tests. And once Delta disappeared, scientists could use PCR tests to tell the difference between BA.1 and BA.2: Samples that caused spike failures contained BA.1, while the ones that didn’t contained BA.2.

In recent weeks, BA.2 has become more common. In Denmark, the variant accounts for up to 65% of new cases, officials said late last week. But it doesn’t appear to be more dangerous: Danish researchers found that people with BA.2 and BA.1 have similar hospitalization rates, the Times reported.

An early analysis of BA.2 released Friday by the British government showed that BA.2 accounts for fewer cases there, but is growing faster than BA.1 across England, the Times reported.

However, British researchers have concluded that vaccines are as effective against BA.2 as they are BA.1.

About 8% of cases in the United States are BA.2, and that percentage is rising quickly, according to Trevor Bedford, a virologist at the Fred Hutchinson Cancer Center in Seattle.

“I’m fairly certain that it will become dominant in the U.S., but I don’t yet know what that would mean for the pandemic,” Nathan Grubaugh, an epidemiologist at the Yale University School of Public Health, told the Times.

BA.2 could lead to a new surge, but it’s more likely that COVID-19 cases will continue to fall in weeks to come, Grubaugh added.

There’s also a chance that the new Omicron variant may create a small increase in cases as they decline overall, or slow the decrease. Current experiments on BA.1 may help scientists improve their projections, according to the Times.

More information

Visit the U.S. Centers for Disease Control and Prevention for more on the Omicron variant.

SOURCE: The New York Times

Robert Preidt and Robin Foster

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