The state's Department of Health said the victim was a "medically fragile" child who had a confirmed case of adenovirus.The unidentified child died Saturday evening at the Wanaque Center for Nursing and Rehabilitation in Haskell, the department said. A staff member at the facility who has since recovered also became ill.
The child, already fragile and suffering respiratory illness, was not confirmed to have a common infection, health officials said.
The nine children who died in the outbreak that began September 26 range in age from toddler to young adult, with a lot of them under age 18. Some strains also cause diarrhea and conjunctivitis.
On Tuesday the New Jersey Department of Health announced the death of six pediatric residents at the center and the infection of 12 additional residents.
The U.S. Centers for Disease Control was assisting state health officials with testing and "expertise", according to the New Jersey Department.
The pediatric centre where a severe viral outbreak left seven young people dead says it's offering grief counselling and a round-the-clock hotline for those affected.
In the same report, the New Jersey spokeswoman Nicole Kirgan said children are particularly at risk with this virus. Adenovirus 7, in the outbreak is linked with communal living arrangements. "As a result, facility staff have diligently implemented all available infection control and prevention measures in order to protect the health and safety of the Wanaque Center's residents".
This remains the last day when a patient showed new symptoms.
In rare cases among people with weakened immune systems, the viruses may cause pneumonia or inflammation of the brain and the tissues around it.
Most adenovirus infections are mild, with symptoms usually lasting about 10 days, according to the CDC.
"People know patients are being held prisoner, but they probably think they have bigger battles in public health to fight, so they just have to let this go", Sophie Harman, a global health expert at Queen Mary University of London, said.