Probing Evolution

Why A Milder Variant of Coronavirus (Δ382) Just Disappeared

Decreased virulence but no boost in transmissibility might have led to its demise.

Image by Mahmoud Ahmed from Pixabay

What is biological fitness? It is the organism’s ability to adapt to and reproduce in different environments. How might a microbe improve its fitness then? It is by being more transmissible and not too virulent because a dead host is a dead end after all.

That is why we have been hearing news or viewpoints that SARS-CoV-2, the causative agent of Covid-19, is becoming more transmissible and less virulent. While the former is true with the infamous D614G mutation (with >70% worldwide prevalence), no robust evidence has supported the latter. A few cohort studies have observed no difference in death rates between patients infected with the D614G-mutated and -unmutated SARS-CoV-2.

What the D614G Mutation Means for Covid-19 Spread, Fatality, Treatment, and Vaccine

New evidence for a milder SARS-CoV-2 variant