The clearest sign that D614G has an effect on the spread of SARS-CoV-2 in humans comes from an ambitious UK effort called the COVID-19 Genomics UK Consortium, which has analysed genomes of around 25,000 viral samples. From these data, researchers have identified more than 1,300 instances in which a virus entered the United Kingdom and spread, including examples of D- and G-type viruses.
A team led by Andrew Rambaut, an evolutionary biologist at the University of Edinburgh, UK, epidemiologist Erik Volz, at Imperial College London, and biologist Thomas Connor at Cardiff University, studied the UK spread of 62 COVID-19 clusters seeded by D viruses and 245 by G viruses7. The researchers found no clinical differences in people infected with either virus. However, G viruses tended to transmit slightly faster than lineages that didn’t carry the change, and formed larger clusters of infections. Their estimates of the difference in transmission rates hover around 20%, Volz says, but the true value could be a bit higher or lower. “There’s not a large effect in absolute terms,” says Rambaut.