Scientists have identified a newer, more contagious coronavirus mutation that they say has become dominant globally, reports the Chicago Tribune.

Mutations happen naturally in viruses, and there are multiple strains of the novel coronavirus. One strain, called D614G, appears to have developed rapidly, quickly becoming a major player and surpassing the original strain in some cases, according to investigators from Los Alamos National Laboratory. This is a worrisome development, study lead Bette Korber reported on her Facebook page.

“When viruses with this mutation enter a population, they rapidly begin to take over the local epidemic, thus they are more transmissible,” she wrote. 

The study team shared their findings before peer review so that vaccine developers, who may be using older strains of the virus in their research, are aware of what they may be dealing with, according to the Chicago Tribune. Ongoing mutations can force vaccine makers to play catch-up, as they do yearly with common influenza viruses.

While it’s not clear where it emerged, the researchers have traced the new mutation to various locations around the globe and in the United States. It was present in Italy early in the pandemic, and in March quickly edged out the original strain of the virus in Washington and New York, the Tribune reports.

In other coronavirus news:

GI symptoms not as prevalent as thought in COVID-19, say gastroenterologists: Gastrointestinal symptoms are not as common in COVID-19 as previously estimated, according to the American Gastroenterological Association. In a new set of guidelines, the group reports that the overall prevalence is about 8% for diarrhea, 8% for nausea and/or vomiting, and 4% for abdominal pain. However infrequent, COVID-19 still does present atypically with GI symptoms, the group reminds clinicians. When a patient experiences new signs of fever and upper respiratory infection after the onset of GI symptoms, testing for COVID-19 should be considered, it recommends.