Two were reported in Atlantic County, and one was reported in Cumberland, Monmouth, Morris and Union counties each.
State Health Commissioner Judith Persichilli said the cases are a combination of both some staff and students.
"I have to remind you that to qualify as an outbreak in a school...it is three cases that are epidemiologically connected and are not from the same household or have otherwise another connection," Persichilli said.
The definition of in-school outbreak increased to three cases this year.
The six outbreaks were all from in-school transmission.
Meanwhile, Gov. Phil Murphy said the state expects "a supply/demand challenge, at least for a number of weeks," when booster shots are authorized.
Murphy said now is the time for the unvaccinated to get their shots, because "we do anticipate demand for shots to increase greatly."
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