By Stephanie Stahl

TRENTON, N.J. (CBS) — There are new concerns about a surge of COVID-19 cases in New Jersey, mainly among people who aren’t vaccinated. Officials also revealed more than 3,000 breakthrough coronavirus cases.

Breakthrough cases are cases in which people who are fully vaccinated still get the virus.

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There’s been a marked increase in COVID-19 cases among children in the Garden State, but officials say the new cases aren’t as serious and for now, Gov. Phil Murphy maintains there is no need for renewed restrictions, like what’s happening with masks in Los Angeles.

“We watch this like a hawk and our strong, strong, strong preference is to not go back,” Murphy said. “We are among the most vaccinated states in the country, and that’s a huge positive.”

But, even with Gov. Murphy’s encouraging numbers on vaccinations in New Jersey, COVID-19 cases are up over 100% since the Fourth of July.

“We do not have a pandemic among the vaccinated, we only have a pandemic among the unvaccinated,” Murphy said.

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Most new COVID-19 cases in New Jersey are among young people who haven’t been vaccinated and in children under 12 who aren’t eligible.

“Case rates per 100,000 have increased 29% among those 4 years of age and under,” Persichilli said.

Another troubling trend is breakthrough COVID-19 cases in New Jersey.

There are 3,474  breakthrough cases, 84 are hospitalized, and 31 people who were vaccinated died from COVID-19 anyway.

But, Gov. Murphy says the numbers are relatively small considering the 4.4 million people who are vaccinated.

“This means the vaccines are 99.98% effective in protecting you against a case of COVID that would require you to be admitted to the hospital,” Murphy said.

While hospitalizations have increased, they’re nowhere near what they were and people aren’t getting as sick, but there are still concerns the Delta variant could cause another serious spike in cases.

“For your family, for your community for public health, for common sense, for your own health, please go get vaccinated,” Murphy said.

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Officials say most of the breakthrough cases are not that serious and are happening mainly to people who have auto-immune complications.

Stephanie Stahl