The COVID-19 virus has become more infectious in the course of the pandemic – but not more lethal, according to a major new genomic analysis.
The findings may help explain why infection rates are surging in countries such as the USA and Brazil, where there are not effective containment policies.
The increased infectivity is caused by a mutation called D614G, which is now in the dominant strain circulating worldwide, according to the analysis published in Cell.
The researchers say the mutation makes a "small but effective" change in the virus’s spike glycoprotein.
Researcher Dr Thushan de Silva, Senior Clinical Lecturer in Infectious Diseases at the University of Sheffield, UK, said: “We have been sequencing SARS-CoV-2 strains in Sheffield since early in the pandemic and this allowed us to partner with our collaborators to show this mutation had become dominant in circulating strains. The full peer-reviewed study published today confirms this, and also that the new D614G genome mutation variant is also more infectious under laboratory conditions.
“Data provided by our team in Sheffield suggested that the new strain was associated with higher viral loads in the upper respiratory tract of patients with COVID-19, meaning the virus’s ability to infect people could be increased.
“Fortunately at this stage, it does not seem that viruses with D614G cause more severe disease.”
Researcher Dr Will Fischer, from Los Alamos National Laboratory, USA, said: “It’s remarkable to me that this increase in infectivity was detected by careful observation of sequence data alone, and that our experimental colleagues could confirm it with live virus in such a short time.”
The USA reported more than 57,000 new cases of infection yesterday and 687 deaths while Brazil reported more than 47,000 cases and 1,277 deaths from the virus and India reported more than 21,000 cases and 377 deaths.
Tracking SARS-CoV-2 Spike mutations: evidence for increased infectivity of D614G. Cell 2 July 2020
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