The highly contagious strain that originated in India and is surging around the globe now accounts for 41% of new variant cases in the Garden State last month, overtaking the Alpha variant that was first documented in the United Kingdom.
For the week ending June 26, Delta accounted for 70% of identified variant cases.
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Murphy stressed that health experts say the three available vaccines are effective against the variant, and he urged people to get vaccinated.
"Virtually all COVID-19 hospitalizations and deaths are among those who are unvaccinated," state Health Commissioner Judith Persichilli said. "Available vaccines are effective against the delta variant, preventing serious disease and hospitalization."
Five weeks ago, nearly every state in the country was reporting decreasing or declining case rates. Now, with more than 50% of Americans still not fully vaccinated, experts say that unvaccinated pockets of the country, in combination with the rapidly spreading Delta variant, appear to be driving outbreaks in communities across the country.
Delta gets its name from the World Health Organization, which names notable variants after letters of the Greek alphabet.
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More than 5.1 million people have been fully vaccinated in New Jersey, Murphy said, which is about 66% of the eligible population, according to the Centers for Disease Control and Prevention, compared with about 56% for the country overall.
The seven-day rolling average of daily new cases in New Jersey rose the past two weeks from 235 new cases per day on June 26 to 264 on Sunday.
The seven-day rolling average of daily deaths fell, going from nine deaths a day on June 26 to almost five a day on Sunday, according to data from Johns Hopkins University.
Meanwhile, New Jersey's rate of transmission ticked up above 1 -- to 1.01, for the first time since late January.
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