A new sub-variant of omicron, BA.2, has been detected in Connecticut. Here’s what we know about it.
A newly-identified sub-variant of omicron, BA.2, was first reported in Connecticut earlier this week. Slightly different from the BA.1 lineage of omicron that has driven the most recent surge of COVID-19 cases in Connecticut, BA.2 is still somewhat unknown to scientists.
Here’s what we know about it so far — and what experts say about how concerned we should be:
When did BA.2 appear in Connecticut?
On Tuesday, Nathan Grubaugh, an assistant professor of epidemiology at the Yale School of Public Health who runs a lab tracking the spread of COVID-19 variants in Connecticut, announced on Twitter that his lab had detected the first case of BA.2 in the state. The sub-variant was detected in a sample collected from Fairfield County on Jan. 8.
How concerned should we be about BA.2?
Dr. Peter Hotez, a vaccine scientist at the National School of Tropical Medicine at Baylor College of Medicine, said that at this point, he is not overly concerned about BA.2, which has already appeared in the Houston region where he lives.
“I tend to not get too exercised about variants until they really start to accelerate — we watch them all, but it’s hard to know whether this one is going to be game-changing or not,” he said during a press call organized by Hartford HealthCare on Thursday.
Some variants — such as beta or lambda — circulate around but never catch on, unlike variants such as delta and omicron, Hotez said.
“We’ll just have to watch this closely, but right now I’m more alarmed about what might be brewing out there in lower-middle-income countries than this BA.2 one specifically,” he said.
How does BA.2 differ from the original omicron variant?
As a sub-variant of omicron, BA.2 is “structurally quite similar to omicron,” said Dr. David Banach, an epidemiologist at UConn Health.
On Twitter, Grubaugh noted that while BA.1 (the original lineage of omicron) and BA.2 share number of mutations, BA.2 brings a slew of its own unique mutations as well. In fact, he said, the two lineages are almost as divergent as the delta and alpha variants of COVID-19.
How well can BA.2 be detected?
While BA.1 and BA.2 are fairly similar, Banach said, BA.2 lacks a specific characteristic that made BA.1 easier to distinguish from other COVID-19 variants, such as delta and alpha. It may be harder to distinguish between cases of BA.1 and BA.2, but that doesn’t mean that cases of BA.2 aren’t detectable.
“It’s getting this term ‘stealth variant,’ and there’s confusion because people think that means that it can’t be detected using our current PCRs, but that’s not the case,” he said. “It can be detected.”
The sub-variant has already been detected abroad — including in India, Denmark and Britain — and has given rise to a smattering of cases in the United States. BA.2 appears the most widespread in Denmark, a country with a robust genome-sequencing infrastructure.
Are we headed for another surge of COVID-19?
Medical experts say it’s too soon to know for certain how quickly BA.2 could spread in the United States — but that the sub-variant may not be as deadly or disruptive as BA.1.
“We haven’t seen data so far to expect this is going to be associated with more infectiousness or more severe illness or less response to vaccine-induced immunity, but I think it’s still too early to make definitive conclusions,” Banach said.
On Twitter, Grubaugh noted that the sub-variant became the dominant lineage of COVID-19 in Denmark within a month, and said he anticipates that it will eventually become the dominant lineage in the United States.
But BA.2 may not drive a resurgence in COVID-19 cases, he said, noting that “there is a lot of recent population immunity from the BA.1 wave, and hopefully not as many susceptible people to infect.”
Courant staff writer Alex Putterman contributed to this report. Eliza Fawcett can be reached at elfawcett@courant.com.
