All viruses mutate. That’s normal. When cells replicate, minute changes occur. And they lead to mutation, which is a change in the genetic sequence. The new coronavirus is more prone to mutations, and that poses a challenge to COVID-19 vaccine-makers.
Why does the SARS-CoV-2, the virus that causes COVID-19, mutate easily? Researchers say the coronavirus has an unusually large RNA. Its RNA polymerase (the enzyme responsible for copying a DNA sequence into an RNA sequence) is error-prone, and hence frequent mutations occur during infections.
There are at least four significant variants in circulation; then, there are sub-types. Some of them are the UK variant (B.1.11.7), the South African variant (B.1.351), the Brazil strains (P1 and P2), and the original Indian variant (B.1.6.17), which has at least two sub-types. They could be more variants and sub-types: all these reflect the challenge of developing vaccines.