'Stealth Omicron': Is subvariant BA.2 a more transmissible strain of COVID and should we be worried?

Just as governments across Europe have voiced their intentions to ease COVID-19-related restrictions, the spectre of another wave of the virus is sparking concern among the scientific community.

Omicron subvariant BA.2, which is being dubbed with the moniker "Stealth Omicron," appears to now be present in 40 countries and gaining ground in the UK, Sweden, India and the US.

In Denmark, it has become the dominant subvariant.

Given the speed at which it is outpacing other Omicron subvariants, it is sparking fears that a more transmissible strain of coronavirus is actively spreading through the community.

Omicron, which is also referred to as B.1.1.529, has three main substrains, BA.1, BA.2, and BA.3, according to the World Health Organisation (WHO).

Up until now, it has been BA.1 that has been dominating with the WHO estimating it makes up a large majority of all Omicron cases.

However, in some places, the BA.2 has begun to spread faster.

The original version of Omicron had specific genetic features that allowed health officials to rapidly differentiate it from Delta using a certain PCR test because of what’s known as “S gene target failure”.

BA.2 doesn't have this same genetic quirk.

A person with BA.2 will still test positive for the coronavirus on a PCR test, but their case won't be flagged as BA.2 unless their original sample goes through genetic sequencing.

“It's not that the test doesn't detect it; it's just that it doesn't look like Omicron,” Dr Wesley Long, a pathologist at Houston Methodist in Texas told the Associated Press.

"Don’t get the impression that ‘stealth Omicron’ means we can’t detect it. All of our PCR tests can still detect it”.

The UK Health Security Agency designated the BA.2 as a variant under investigation