Delta variant’s global spread raises question: will Covid-19 become more infectious?

As the highly infectious Delta variant challenges pandemic control efforts around the world, a great unknown looms large: what might the virus behind Covid-19 do next? Scientists widely agree that new mutations of Sars-CoV-2 are likely to emerge as time goes on, bolstering a roster of Greek letters that already includes Alpha, Beta, Gamma and Lambda. The question is whether the virus behind the worst pandemic in a century will evolve to become more or less threatening in terms of its harmfulness to human health, contagiousness and resistance to vaccines. Although the history of past viruses offers potential scenarios for the current pandemic’s trajectory, there is no firm consensus on the threat posed by emerging variants. Experts widely agree that Sars-CoV-2 will continue to circulate in some form or another for years to come, but there is no way of knowing exactly how it will evolve, and not all mutations are necessarily more...