New mutations in the novel coronavirus are constantly being reported. Without targeted testing and evaluation of these mutants, we cannot (yet) predict their impact. A recent paper that is not yet scrutinized by other scientists in a peer review reported a more transmissible form of the virus (https://www.biorxiv.org/content/10.1101/2020.04.29.069054v1). This article from ‘The Atlantic’ by a well known science writer Ed Yong, discusses why such conclusions are premature.
https://www.theatlantic.com/health/archive/2020/05/coronavirus-strains-transmissible/611239/