That is frightening. Increasing the mutation rate must carry a large unknown risk. Also surely the first thing to mutate will be self-defeating resistance to that drug...
Btw, one of the best markers for overconfident but uninformed analysis is overinterpreting the fact that we have all these strains of SARS-CoV-2 as suggesting they have different degrees of infectiousness or health impacts. Certainly the different flu strains do, and, thanks to fine-grained sequencing efforts (Nextstrain in particular is doing awesome work) we can see lots of strains of this one, but Trevor Bedford has estimated that we have about a year or more before the variation in strains has an impact other than being able to "fingerprint" the chains of transmission.
Detecting small differences in effects between different genetic variants of the virus would require large statistical populations, and wide testing for the different genetic variants.
Without that, Trevor is only making an educated guess?
Also, for people who don't know, Trevor is arguably the single most expert person in the world to weigh in on this.
And here's the specific thread where he predicts it will take a few years for the virus to mutate enough to significantly hinder a vaccine: https://twitter.com/trvrb/status/1242628550563250176
“There have been only 11 mutations to proteins that are widely distributed. These are potentially functionally distinct variants that deserve attention and experimental and clinical follow up. But my expectation would be most have ‘little effect’ without further data“.
“in terms of immunity, there is a single widely circulating mutation in spike protein (D614G). Spike is present on the surface of the virus and is what the immune system sees“
“If you follow a transmission chain in which one person with flu infects another person and they infect another person and so on, you'll find that the virus mutates about once every 10 days across its genome. Almost all of these mutations will have little to no effect on virus function. Evolution weeds out the mutations that ‘break’ the virus and mutations that make a virus replicate better are extremely rare.”
The effects of the OP drug increasing the mutation rate would need to be modelled to understand risks.
“In this report we describe the first major evolutionary event of the SARS-CoV-2 virus following its emergence into the human population. Although the biological consequences of this deletion remain unknown, the alteration of the N gene transcription would suggest this may have an impact on virus phenotype.“
However they don’t speculate on whether that strain is more likely to spread (it clearly is a viable mutation).