SARS-CoV-2, the virus that causes COVID-19, is accumulating genetic mutations, one of which may have made it more contagious, according to a study of more than 5,000 patients in Houston, Texas.

“The virus continues to mutate as it rips through the world.”

That mutation, called D614G, is located in the spike protein that pries open our cells for viral entry, according to the study in mBIO. Researchers report this is the largest peer-reviewed study of SARS-CoV-2 genome sequences in one metropolitan region of the US to date.

The paper shows “the virus is mutating due to a combination of neutral drift—which just means random genetic changes that don’t help or hurt the virus—and pressure from our immune systems,” says coauthor Ilya Finkelstein, associate professor of molecular biosciences at the University of Texas at Austin.

During the initial wave of the pandemic, 71% of the novel coronaviruses identified in patients in Houston had this mutation. When the second wave of the outbreak hit Houston during the summer, this variant had leaped to 99.9% prevalence, mirroring a trend observed around the world.

Read the full article about SARS-CoV-2 by Marc Airhart at Futurity.