The writer is a science commentator

Early in the pandemic, scientists were uncertain about how quickly the new coronavirus would mutate. Since then, a steady stream of viral variants has dashed hopes that it might be a slow mover. The Delta variant first identified in India is now the dominant strain in the UK and is spreading rapidly in Europe and the US. Delta is much more transmissible than even the previously fastest-spreading variant although, thankfully, vaccines still appear to be highly effective against it. 

It can seem like the onward march of the variants is inevitable and that the virus will mutate to counter our every move. This isn’t necessarily the case. Sars-Cov-2 has proved an unexpectedly fast adversary, but it still has to follow the basic rules of evolution, meaning that its options aren’t limitless.