MORE INFECTIOUS, BUT LESS SEVERE COVID-19 STRAIN, DOMINATES CASES

After it jumped between millions of humans, SARS-CoV-2 has suffered many mutations along the way. A particular strain, known as “D614G,” is more adapted to infecting human cells than earlier mutation variants of the coronavirus. As such, it didn’t take long for D614G to become the dominant coronavirus strain seen in new cases across the globe, Tibi Puiu wrote for the online ZME Science on July 3, 2020.

Prior to March, D614G was present in just a few locations across the globe, mostly spreading in Europe. However, small changes in the virus’ “spike” protein — a protrusion on the surface of the virus that latches on to cell receptors in order to commence infection — has made D614G much more suited to infecting humans. By the end of March, D614G was already present across the world, becoming the dominant strain, replacing D614.

These findings were revealed by researchers at Los Alamos National Laboratory in New Mexico, Duke University in North Carolina, and the University of Sheffield in the UK, who analyzed genome samples from GISID — a huge database of genome sequences shared among researchers worldwide. Tens of thousands of sequences are currently available, enabling researchers to quickly identify virus variants that show signs of rising to the top. Their study was published in the journal Cell.

Dr. Thushan de Silva, Senior Clinical Lecturer in Infectious Diseases at the University of Sheffield, has been studying the new D614G genome mutation variant in the lab since the pandemic first started. It was clear since then that the strain was more potent. However, de Silva found that strain is even more infectious in the real world than in the lab. “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,” de Silva said in a statement for the press. “Fortunately at this stage, it does not seem that viruses with D614G cause more severe disease.”