The US Centers for Disease Control and Prevention has ruled out the pandemic coronavirus, SARS-CoV-2, as a possible cause of the puzzling, international outbreak of severe hepatitis (liver inflammation) in children, according to a statement released Friday.

The outbreak has sickened more than 170 children in more than a dozen countries in recent months, with case counts ticking up by the day. Around 10 percent of the children—mostly under the age of 10—have required liver transplants. The World Health Organization has reported one death.

In the US, officials in at least five states have reported at least 25 confirmed or possible cases: Alabama (9), North Carolina (2), Wisconsin (4), Illinois (3), and California (7). At least three of the US cases have required liver transplants and officials in Wisconsin are investigating a possible death linked to the outbreak.