Researchers at the Institut Pasteur are analyzing hundreds of blood samples from Guinean Ebola patients in an effort to determine if the new variation poses a higher risk of transmission, according to the BBC.

“We’ve now seen several cases that don’t have any symptoms at all, asymptomatic cases,” said human geneticist Dr. Anavaj Sakuntabhai. “These people may be the people who can spread the virus better, but we still don’t know that yet. A virus can change itself to less deadly, but more contagious and that’s something we are afraid of.”

Although virus mutations are common, researchers are concerned that Ebola could eventually morph into an airborne disease if given enough time.