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No, ‘deltacron’ and the BA.2 subvariant of COVID-19 are not the same

Despite some social media users referring to “deltacron” as BA.2, the delta-omicron hybrid and omicron subvariant are different. Here’s what we know about both.
Credit: AdobeStock
Test tubes show results for deltacron and BA.2, which are two different COVID-19 strains.

UPDATE: Omicron subvariant BA.2 is now the dominant strain of COVID-19 in the U.S. Click here for our latest reporting. The original story continues as written below: 

New coronavirus variants have been identified throughout the pandemic, often leading to questions and confusion as new information emerges. 

Two years into the pandemic, health experts continue to find new strains of the virus that causes COVID-19, including one that’s been dubbed “deltacron.” There’s also a subvariant of omicron called BA.2, cases of which are rising in the U.S. and other countries throughout the globe. 

But there’s some confusion about whether the BA.2 subvariant of COVID-19 and “deltacron,” both of which have recently made headlines, are the same. Google Trends data from the past week shows people have been asking the question, and several Twitter users have referred to “deltacron” as BA.2

THE QUESTION

Are the BA.2 COVID-19 subvariant and “deltacron” the same?

THE SOURCES

THE ANSWER

This is false.

No, the BA.2 omicron subvariant and “deltacron” are not the same.

WHAT WE FOUND

BA.2 and “deltacron,” are not the same, according to medical experts. BA.2, often referred to as “stealth” omicron, is a subvariant of the original omicron variant, or BA.1. The hybrid virus informally referred to as “deltacron,” on the other hand, combines the delta and original omicron variants.

“Deltacron” is a delta-omicron hybrid

Despite its previous assertions that the delta and omicrons variants had not combined, the World Health Organization (WHO) has since acknowledged such a hybrid virus. 

Lisa Geddes wrote for the Global Alliance for Vaccines and Immunizations (GAVI) that hybrid or “recombinant” viruses arise “when more than one variant infects the same person at the same time, and they interact during replication within the same cell.” 

“The recombinant... is something that is expected given the large amount of circulation, the intense amount of circulation that we saw with both omicron and delta,” Maria Van Kerkhove, Ph.D., WHO Technical Lead on COVID-19, said during a press conference on March 9. “If you remember, with the emergence of omicron in some countries, the wave of delta had already passed and so circulation was at a low level. But in other countries in Europe, for example, delta was still circulating at quite a high level when omicron emerged.”

The recombinant virus was designated a “variant under monitoring” on March 9. The WHO hasn’t seen “any change in severity” associated with the recombinant virus, Kerkhove said. 

During the March 9 press conference, Kerkhove said there were “very low levels” of detection of the recombinant delta-omicron virus in France, the Netherlands and Denmark.

Delta-omicron recombinant viruses are “exceedingly rare” in the United States, a spokesperson for the Centers for Disease Control and Prevention (CDC) told VERIFY. Nine cases have been identified as delta-omicron recombinants out of more than 400,000 analyzed by the CDC’s genomic surveillance system from December 2021 to present. The recombinant virus samples were collected from five different U.S. states.

An early study that hasn’t yet been peer-reviewed, funded in part by the CDC, also found only two cases of a delta-omicron recombinant virus in more than 29,000 positive COVID-19 samples taken between November 2021 and February 2022.

Christopher Doern, Ph.D, associate professor of pathology and director of clinical microbiology at Virginia Commonwealth University, says the recombinant virus is unlikely to cause a surge since omicron is the dominant variant in the U.S.

“We haven't seen a case of delta, we don't think, in quite a while. It just seems unlikely that this would be something that would surge or become a dominant strain, because there just isn't any delta variant around,” he said. 

BA.2 is an omicron subvariant

Cases of BA.2, the omicron subvariant, are much more common in the U.S. than delta-omicron hybrid cases. From March 13-19, BA.2 accounted for nearly 35% of COVID-19 cases, according to estimates from the CDC. That’s compared to about 23% of COVID-19 cases from BA.2 in the U.S. during the previous week. 

Experts say BA.2 is more contagious than the original version of omicron and is sometimes more difficult to distinguish from the delta variant through testing. But vaccines still provide the same level of protection against severe illness and hospitalization from the BA.2 subvariant compared to other variants, medical experts previously told VERIFY

The WHO has labeled omicron and its sublineages, including BA.2, as a “variant of concern.”

More from VERIFY: Yes, 'stealth' omicron cases have been reported in the U.S.

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