QuickCheck: Was a new Covid-19 variant discovered in Sarawak?

THERE IS talk that a new and highly infectious Covid-19 variant has been discovered in Sarawak.

Is this true?



What was actually detected in Sarawak were two Covid-19 Omicron subvariants, namely BA.2.12.1 and BA.5.

These two subvariants are not entirely new as they have surfaced elsewhere, but they are new to Malaysia as they had not been detected here before.

The Omicron subvariant BA.2.12.1 was first detected in North America and accounts for 26% of samples sequenced there whereas BA.5 and its close sibling BA.4 are spreading rapidly in South Africa, comprising more than 90% of genomes sequenced there.

Universiti Malaysia Sarawak's Institute of Health and Community Medicine (IHCM) director Prof Dr David Perera said the first incidences of the BA.2.12.1 and BA.5 sub-variants were detected from a case in Kuching and Sibu respectively in the last week of May.

"Subsequently, an additional case of BA 2.12.1 and three cases of BA.5 were detected in Kuching in the second and third weeks of June," he said in a statement on Thursday (June 23).

The World Health Organisation (WHO) has flagged BA.2.12.1 and BA.5 as highly infectious with faster transmission rates than the parent Omicron variant.

But how are these subvariants named and why aren't they given their own greek letter?

SARS-CoV-2, the virus behind Covid-19, replicates rapidly and each time it does it acquires mutations.

So technically, this means millions of variants probably arise every day, but the vast majority of these mutations don't improve the virus' ability to survive and reproduce so they are eventually out-competed by more resilient versions.

Some new strains do gain traction and researchers conducting genomic surveillance flag samples that all have the same set of distinct mutations.

These samples are then studied to see how they fit on the SARS-CoV-2 family tree.

If they can be traced to a common recent ancestor, then they represent a distinct lineage of the virus.

These lineages so far would represent a subvariant of the dominant variant (in this case Omicron) and are labelled following in a sequence from A to Z, then from AA to AZ, BA to BZ, and so on.

The numbers in the label indicate the order of branches from that lineage. As an example, BA.1, BA.2, BA.3, BA.4 and BA.5 are the first five branches of the original Omicron ancestor.

BA.2.12.1 is the twelfth lineage to branch off from BA.2, and the first-named branch of that 'bush'.

If a subvariant (or variant) has features that distinguishes itself enough from other subvariants that make it better at reproducing, becoming transmissible or increasing its severity, then the World Health Organisation (WHO) might determine it to be a 'variant of concern'.

The WHO will then change its name to a Greek letter.


1. https://www.thestar.com.my/news/nation/2022/06/23/covid-19-highly-infectious-omicron-sub-variants-detected-in-sarawak

2. https://www.nature.com/articles/d41586-022-01466-9

3. https://www.nature.com/articles/s41586-022-04980-y

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