How that preprint about a 'more contagious strain' of coronavirus changed in peer review

On May 5, 2020, news broke about a reportedly more contagious variant of SARS-CoV-2—the virus that causes COVID-19—based on a preliminary paper posted to the preprint server bioRxiv. The preprint stated that a variant of the virus with a particular mutation leading to an amino acid change, D614G, in its spike protein was "more transmissible" than other forms and represented an "urgent concern" for containment and vaccine development. But in the days that followed, criticisms of these assertions surfaced. On July 2, the journal Cell published a revised and peer-reviewed version of the paper that offers additional experimental and clinical data about the D614G variant suggesting that it may be more infectious, but concludes that we still cannot be certain about whether the variant makes SARS-CoV-2 more transmissible or leads to more severe disease.