[lamontcg]

> The novel coronavirus was sufficiently optimized so that no serious mutations occurred for nine months.

D614G happened almost immediately. There were also likely mutations that made it better adapted to mammals/humans that we never saw before it became "good enough" to form a pandemic virus in humans.

Beyond that it was good enough with an R0 of >3.0 and ability to infect the entire world's population that it spread globally and faced no selection pressure to mutate. Once it was facing a population with a climbing amount of immunity it was forced to get better at infecting in order to go after the remaining fully susceptible population, and it faced selection pressure to become more immune evasive and to reinfect.