The BA.2 variant has officially become the dominant strain in the United States, with the latest data showing that more than half of all reported cases last week were caused by the highly contagious version of omicron.

BA.2 Infections In The U.S.

The U.S. Centers for Disease Control and Prevention (CDC) said Tuesday that the BA.2 subvariant of omicron has surpassed other strains in terms of transmissions based on its genomic surveillance. For the week ending March 26, BA.2 caused between 51% and 59% of all new infections, surpassing the estimated 39% it recorded the week before.

The public health agency’s genomic surveillance system gathers data by sequencing SARS-CoV-2 specimens obtained via the National SARS-CoV-2 Strain Surveillance program and those collected by CDC-contracted commercial and academic laboratories and state or local public health laboratories. Thousands of sequences are analyzed weekly to identify and monitor the spread of the coronavirus variants amid the ongoing pandemic.

In the latest weekly report, the notorious omicron subvariant caused more than 70% of all new infections in the Northeast, the hardest-hit region. On the other hand, the South and Mountain West witnessed the fewest transmissions even though they recorded slightly more than one-third of the infections in the previous week.

Omicron Subvariant Around The World

The World Health Organization acknowledged last week that BA.2 subvariant was already the main cause of COVID-19 worldwide, outnumbering the cases attributed to two other omicron subvariants, BA.1 and BA 1.1. The spike in BA.2 cases has pushed the global figures to rise a few months after international transmissions dipped in January.

The takeover of the subvariant dubbed “stealth omicron” was mostly felt in the United Kingdom since the country recently lifted its pandemic restrictions. Even though the U.K. population was more highly vaccinated than the U.S., the more contagious version of the novel coronavirus was able to spread rapidly, creating a new COVID-19 wave that triggered an increase in transmissions, hospitalizations and deaths since the end of February.

The U.S. has been following the U.K. by about three weeks in terms of developments, so health officials are already preparing for what could be another COVID-19 wave. However, because there has only been limited data on what the subvariant can do, health and medical experts do not exactly know what to expect, as per CNN.

Plateauing Cases In America

The reason experts are not sure what they should expect from here on out has something to do with what is already happening in the country. The BA.2 subvariant started penetrating the country by the end of January, but case numbers have plateaued except in 13 states where weekly averages have risen. But if experts were to make assumptions based on what’s happening in the U.K., then it’s likely for the COVID-19 cases in America to go up again.

"We're not immune from what happens in Europe," former CDC Director Dr. Tom Frieden said. "In Europe, you see BA.2 becoming predominant and driving a resurgence, and the likelihood that will not happen in the U.S. is pretty low, really. I do think part of the reason that we're plateauing is that we're about to start going up again.”

Frieden believed that authorities already anticipated what could happen next; that is why the U.S. Food and Drug Administration authorized additional boosters for people aged 50 and above on the same day the CDC announced that BA.2 was already the dominant strain.

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