A mutation of Covid-19 that is now most common around the world is helping spread the virus more quickly than at the start of the pandemic, a UK expert said on Wednesday. A strain of the coronavirus found in three-quarters of cases around the world forms clusters of infections more quickly and leads to larger outbreaks, Nick Loman of Birmingham University said. Prof Loman said the mutation, known as D614G, should not affect the search for a vaccine and did not have a measurable impact on human health. “We didn't see any significant association with survival or the length of hospital stays with this mutation,” Prof Loman, a professor in microbial genomics and bioinformatics, told the BBC. He said researchers were tracking thousands of mutations but said that the 614G mutation had been noteworthy for a while and differed from that found in cases around the suspected original outbreak in Wuhan, China. Analysis carried out by the Covid-19 Genomics UK Consortium suggested that the virus with the 614G variant grew 1.22 times faster than that with the 614D version, which was seen in Wuhan. “We have been noticing in the UK and worldwide that this mutation has been increasing in frequency,” he said. Mr Loman said the work was based on a data set in the UK of about 40,000 genomes, the complete set of genes in a cell. “It does seem to have an impact, particularly on transmissibility. It's a small impact, we think,” he said. “But we found that by testing what happened in the UK, viruses that contain the G type of mutation seemed to form clusters of cases faster, which ended up being bigger, than the viruses with the D mutation”.