Mutation, Mutation!

There are reports from the USA, looking at changes in the genotypes of the Covid-19 virus, suggesting that it is becoming more infective (https://www.theguardian.com/world/2020/sep/24/coronavirus-mutate-contagious-study-us-cases). They also note that there is no evidence that the virus is becoming more lethal and suggest 'that mutation is still likely when we have a vaccine'. I appreciate that this is not the intention, but the coverage gives the impression that mutation is a deliberate 'policy'. Mutation occurs, whenever organisms reproduce or replicate. With its crossing the species barrier to humans, there has never been more copying of the short RNA sequence that largely makes up this virus. Micro-organisms, such as bacteria and viruses, reproduce very quickly (much much faster than we humans), so there are bound to be lots of mutations in the viral populations. Most of these mutations will be short-lived and have little or no influence on the viral population. Viruses, like everything else, are subject to Darwinian natural selection. The virus that made the 'jump' from bats to humans probably had mutations facilitating that move. The virus didn't choose to change host species. Those that could, however, suddenly had major replicating and population expanding possibilities. The currently recorded mutations are also random events. Covid-19 might well be becoming more infective as certain mutations might enable the virus to partially overcome some of the human attempts at limiting transmission (such as social spacing). The evidence that the virus is not becoming more lethal is very likely to reflect the fact that killing the host reduces the replication opportunities for the virus (so, like any good parasite, infections producing milder forms of the disease might well be getting more common). It's absolutely certain that mutation will continue when a vaccination is found and utilised (this happens with monotonous regularity in seasonal influenza). The vaccination will constitute a selection pressure for the virus (as do antibiotics for bacteria, producing 'superbugs'). Only the viruses that can infect, get the chance to replicate. So those with mutations that allow them to overcome the immune defences of the vaccinated host will get the chance to replicate in initially well-protected (vaccinated) populations.