New Jersey Department of Health Commissioner Dr. Shereef Elnahal, left, speaks about the adenovirus outbreak as New Jersey Gov. Phil Murphy looks on during a press conference at the The Wanaque Center for Nursing and Rehabilitation on Wednesday, Oct. 24, 2018 in Wanaque, N.J. There have been 18 cases overall at the Wanaque Center for Nursing and Rehabilitation in Haskell, about 30 miles (50 kilometers) northwest of New York, officials said. The 227-bed, for-profit facility has a pediatric unit but also cares for elderly residents. (Michael Karas/The Record via AP)

New Jersey health officials said Thursday tests confirmed a 19th patient has been infected in a viral outbreak at a pediatric rehabilitation center that has killed seven people.

The unidentified person had already been ill so the diagnosis does not necessarily mean the virus is still spreading, according to Health Department spokeswoman Donna Leusner.

The outbreak won't be declared over until the Wanaque Center for Nursing and Rehabilitation can go four weeks without any new cases of people being infected with a type of germ called adenovirus 7, Health Commissioner Dr. Shereef Elnahal said this week .

The seven people who died this month were children and at least one young adult, all in a respiratory unit where patients receive long-term help with breathing.

The identities of those who died and the affected patients have not been disclosed.

Adenovirus usually poses little risk for healthy people and typically causes mild cold or flu symptoms, including sore throats, fever, coughs and sneezes. Some strains also cause diarrhea and conjunctivitis.

The strain found in the rehab center outbreak is among the more potent types. It sometimes causes more serious respiratory illness, especially among those with weak immune systems.

Many of the children at the facility require ventilators for breathing, and some have spent all or most of their lives there, the commissioner said. He described the patients as "fragile."

New Jersey Governor Phil Murphy speaks about the adenovirus outbreak as New Jersey Department of Health Commissioner Dr. Shereef Elnahal looks during a press conference at the The Wanaque Center for Nursing and Rehabilitation on Wednesday, Oct. 24, 2018 in Wanaque, N.J. There have been 18 cases overall at the Wanaque Center for Nursing and Rehabilitation in Haskell, about 30 miles (50 kilometers) northwest of New York, officials said. The 227-bed, for-profit facility has a pediatric unit but also cares for elderly residents. (Michael Karas/The Record via AP)

It's unlikely that there's a broader threat, he said.

Rowena Bautista, the center's administrator, said Thursday in a statement the community "feels a tremendous sense of loss."

She also said the center is working with the state Health Department and the Centers for Disease Control and Prevention in addition to offering professional grief counselors and setting up a 24-7 hotline.

The number is being shared with families, but not the public.

Elnahal said the first symptoms showed up Sept. 26, and the state was notified of an outbreak Oct. 9.

The center did not provide new details on the timeline of the events at the center, including how and when families were notified.

Health officials said they have teams at the facility monitoring the infection, and the center has closed to new patients.

The 227-bed for-profit facility has a pediatric center and also cares for elderly residents.