The affected children range in age from under 1 to 7 years old.
All were previously hospitalized between October 2021 and February 2022, and all have recovered.
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None of the children underwent liver transplants. All of the children tested negative for COVID.
There were no deaths.
The Health Department issued an alert in April advising medical providers to monitor for suspect cases of hepatitis of unknown origin and report cases to the department.
Data collected by the department was provided to the CDC, which then analyzed the data to determine which cases met the criteria to be investigated.
U.S. health officials have said more than 180 cases of the mysterious and severe liver disease in children in 36 states that are under investigation.
ABC Chief Medical Correspondent Dr. Jen Ashton detailed on "Good Morning America" what experts know about this outbreak and symptoms parents should monitor.
Note: This interview was edited for clarity.
What do we know about this outbreak?
Ashton: The CDC put out an alert for health care providers two weeks ago. They're tracking these cases back to October, and they do expect this number to grow.
Hepatitis is a catch-all term for acute liver injury. In the pediatric population right now, experts think that most of these cases are associated with an adenovirus 41, which is a common gastrointestinal virus, but not all of them.
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Ninety percent of the children affected have required hospitalizations. There have tragically been five deaths, and 14% of cases have required liver transplantation.
This is an evolving situation that right now, experts are in the stages of accumulating data and observation.
Is COVID-19 somehow involved?
Ashton: Experts don't think so. Remember, some of these children coincidentally have had COVID-19.
I just spoke to CDC Director Dr. Rochelle Walensky. She wanted me to emphasize that the majority of cases have been in children ages 2 to 5. These children, as we all know, are not eligible for the COVID vaccine, so this outbreak has nothing to do with the vaccine.
Right now, researchers can see cases of hepatitis following any virus. It's still unclear what's causing these cases.
Aren't kids here in the U.S. vaccinated against hepatitis?
Ashton: They are, but not this strain of hepatitis. There's hepatitis A, B, C and D. These cases of hepatitis are none of those, so it's mystifying to public health officials at this point.
Right now, the CDC is really increasing the alert to parents to be on the lookout for signs and symptoms.
What are some of the signs and symptoms?
Ashton: Symptoms include fever, fatigue, nausea, vomiting, abdominal pain, joint pain and jaundice -- a yellowing of the white part of the eyes or the skin or a change in the color of urine or stool.
This obviously should drive the parents to alert their pediatricians as quickly as possible. I want to emphasize even though the cases are growing, this is still very uncommon.
Awareness is key.
The Associated Press contributed to this report.
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