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 department said in a statement on Friday that the latest death involved a child who was "medically fragile with respiratory illness".
"To date, confirmed cases became ill between September 26 and October 22", according to a health department statement.
As of the announcement, the total number of confirmed adenovirus cases at the facility is at 23, with seven deaths confirmed to be linked to the outbreak.
Adenovirus usually poses little risk for healthy people.
A health department spokesman said: "The strain of adenovirus seen in this outbreak is associated with communal living arrangements and known to cause severe illness".
Twenty-five pediatric cases of adenovirus have been connected to the outbreak at this facility, officials said.More news: Migrant caravan in pictures: A river of people moving north
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The Wanaque Center, about 32 miles (50 km) northwest of NY, serves newborns to 22-year-olds who are "medically fragile".
This month, NJ.com reported that in the center's most recent health inspection report, the Centers for Medicare & Medicaid Services gave the facility a "below average" score, and the 2017 report also said the facility "failed to ensure infection control practices were followed". They ranged in age "from a toddler through young adults, but most are under 18".
"We are working every day to ensure all infection control protocols are continuously followed and closely monitoring the situation at the facility", he said.
The state health department has sent a team of investigators to the facility to determine the cause of the outbreak.
While noting that the adenovirus vaccine is only available for United States military personnel, the CDC said that to prevent the spread of the virus wash hands often, avoid touching eyes, nose, and mouth with unwashed hands, and avoid close contact with people who have the virus.
Symptoms include a sore throat, bronchitis, pneumonia, fever, and neurologic disease.
The viruses themselves are also "resistant to many common disinfectants and can remain infectious for long periods on environmental surfaces and medical instruments", the CDC says. "But they're not almost as serious as influenza".