How Covid-19 mutations are changing the pandemic

Early in its existence, Covid-19 gained an ability that would prove decisive in its relationship with human beings. The virus picked up a seemingly small change in its genetic code. It was likely an unfortunate accident – a fragment of genetic information from another virus got muddled up with that of the coronavirus while they were both infecting a bat. Included within this tiny piece of genome, however, were the instructions that altered a key part of the virus – its spike protein. This important protein studs the outside of the coronavirus and is the part that attaches to the outside of cells, helping the rest of the virus to sneak inside where it can replicate. This change to Covid-19's spike protein meant it could hijack an enzyme found in the human body called furin. This enzyme acts like a pair of molecular scissors, normally cutting open hormones and growth factors to activate them. But when furin snips part of the Covid-19 spike protein, which is normally folded in a series of loops on the outside of the virus, it opens like a hinge.