Now that the authorities have reported, and confirmed that the UK variant has been in Bangladesh since January, this is where we put all that we’ve learned about viruses over the last one year to the test, by trying to explain the UK Variant, aka VOC-202012/01 (denoting it was the first Variant Of Concern in December 2020), lineage B.1.1.7 in layman’s terms.
Last Wednesday (March 10), the head of the Directorate General of Health Services ABM Khurshid Alam told reporters that the UK variant has been present in the country since January, but “there is no conclusive finding yet on whether it is responsible for the surge in Covid-19 cases and positivity rate in the past few days.”
Viruses of course are always mutating, during each replication cycle. The mutations occur within the genetic sequence contained in their RNA (SARS COV-2 is an RNA virus). Due to its loose, single line structure, RNA tends to be more prone to such mutations occurring during the replication process than DNA.
It can be useful to think of each replication cycle as sitting an exam for the virus - its task being to pull off the next copy of itself based on the information contained in its RNA (in SARS COV-2's case), while making as few errors as possible. Each mutation is essentially an error. Human cells also multiply along the same principle, but since we're DNA-based (with some RNA for non-genomic purposes), they are less prone to errors in the process thanks to the double-helix structure of DNA.
It also allows for the human genome to contain billions of base pairs that make up the genetic sequence, compared to an RNA virus that will typically be in the thousands only. SARS COV-2 is actually a bit longer than the average, containing around 30,000 base pairs.
Now each time they replicate, some of these 30,000 base pairs are copied wrongly – that is why it is said viruses are always mutating. They never get a 100% mark. But they get enough right to maintain their structural integrity and remain true to their original character. The problem starts occurring, and we need to start worrying, when many of them start making the same errors, and these errors are seen to occur along key, or biologically significant parts of the virus.
So in the case of the UK variant, it is said to contain 23 mutations. If we return to the exam analogy, we all know how a number of examinees making the same errors will set off alarm bells in the examiner’s mind that they were cheating. The more of these there are, the greater the chance that some real hanky-panky was going on. Similarly, 23 of the same mutations (errors) occurring in a single cluster (in the UK they first spotted this set of errors in 900 cases, now there’s a lot more) is an “unusually large number”.
