Just as the Omicron wave is beginning to spread across the United States, news of a new version of the more transmissible strain, called BA.2, arrives. It's been dubbed "stealth Omicron" by some since it appears to elude detection better than its predecessor.

While some new variants that sounded worrying — like Mu or Lambda — have had minimal influence, and facts remain vague, early signs are that BA.2 seems to be spreading even in countries where the original Omicron lineage, BA.1, is prominent.

“During the same period, the relative frequency of BA.1 has dropped,” according to a statement from the institute. “BA.1 and BA.2 have many differences in their mutations in the most important areas. In fact, the difference between BA.1 and BA.2 is greater than the difference between the original variant and the Alpha variant.”

According to SSI, an initial examination of BA.2 cases in the country "shows no differences in hospitalisations." The effectiveness of the current vaccinations against the subvariant is likewise unknown.

The Omicron branch is also affecting the United Kingdom, Norway, France, India, and Sweden to varying degrees, as is the case in the United States. See the map below for further information, as well as a more comprehensive list here.

The UK Health Security Agency has categorized BA.2 as a "variant under investigation." According to an HSA report, the latest form of Omicron was first detected in the UK on December 6, 2021. There have been 426 confirmed cases to date, with the biggest incidence in London.

“Early analyses suggest an increased growth rate compared to BA.1, however, growth rates have a low level of certainty early in the emergence of a variant and further analysis is needed,” reads the report.

Those allegations could possibly be false because the U.K. Officials believe the offshoot will be more difficult to identify since it lacks a telltale marker in PCR tests that has previously indicated Omicron. While a PCR test would still result in a general positive, such samples would require genomic sequencing, a much more expensive and time-consuming process that is less common for identifying the specific variant involved.

“Omicron BA.2 lacks the genetic deletion on the spike protein which produces S-gene target failure (SGTF) in some polymerase chain reaction (PCR) tests, which has been used as a proxy for Omicron cases previously,” reads the U.K. document.

“[I] think likely scenario is BA.2 just exacerbates what the national Omicron situation is,” said Tom Peacock, a virologist at Imperial College London.

Peacock estimates that BA.2 has dozens of protein changes from BA.1. For a basic impression, look at the first and second lines in the accompanying graphic from South African health officials.

There are conflicting reports as to where BA.2 initially appeared, with some pointing to South Africa, some to India, and yet others to the Philippines.

The Washington State Health Department said two instances of BA.2 were "discovered earlier this month," according to Sinclair Broadcasting's Seattle affiliate, KOMO News.

“It’s too early to tell if we are going to see more cases of this variant,” WA health department spokesperson Shelby Anderson told the outlet. “So far, fewer than 100 confirmed BA.2 cases in the U.S. have been reported.”

At least three cases have been discovered at Houston's Methodist Hospital, which has more robust genomic sequencing than other hospitals.

The United States has yet to recognize BA.2 as a distinct sublineage, whereas the World Health Organization has done so.

However, one anonymous Biden administration source told the Washington Post on Monday that "there is concern about the omicron BA.2 variant," and that the US is preparing and "paying close attention to the BA.2 variant" because of the surge in instances outside.