An additional 12 children at the facility, called the Wanaque Center for Nursing and Rehabilitation in Haskell, New Jersey, have also fallen ill with adenovirus, according to a statement from the New Jersey Department of Health.
These patients' preexisting health issues, as well as their shared environment, may have facilitated the spread of adenovirus, according to the state health department.
Illnesses resulting from this family of viruses are usually fairly minor, although certain strains can cause more severe sicknesses.
Officials say the strain affecting children at the clinic, number seven, is associated with communal living and "can be more severe".
Health officials said there is an "ongoing outbreak investigation" underway and that an inspection team from the agency has been investigating at the facility in Haskell. A team was sent back Tuesday.
A team from the health department were on hand at the center Tuesday to investigate.
Adenoviruses are part of a group of viruses that can infect the membranes or tissue lining of the respiratory tract, eyes, intestines, urinary tract and nervous system, according to the Centers for Disease Control and Prevention.
The names and ages of the children were not released.
"The Wanaque Center for Nursing and Rehabilitation has recently experienced some cases of the Adenovirus in its pediatric unit".
Serious complications are uncommon, but the CDC notes those with "weakened immune systems, or existing respiratory or cardiac disease" are at a higher risk of severe sickness from adenovirus infections.
The Wanaque Center says on its website that it is a for-profit facility that works with "with medically fragile children" from newborn to 22 years old.
Wanaque is a residential facility that cares for "medically fragile" newborns, children and young adults, as well as elderly individuals and those requiring rehabilitation. Messages left with the center were not returned.