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Former NYC Health Commissioner: Threshold For Herd Immunity Against COVID-19 Will Be Higher Due To Highly Contagious Delta Variant

NEW YORK (CBSNewYork) -- There's more concern over the highly contagious Delta variant of the coronavirus.

As cases surge, New York City's former health commissioner, Dr. Tom Frieden, has a warning.

On Twitter, he said, "The higher infectivity of Delta means the threshold for herd immunity will be higher."

He says while a 70% vaccination rate may have been enough to reach herd immunity against the initial strain of COVID-19, it "likely isn't high enough against Delta, as shown by case increases in places like the UK and Israel, which have high vaccination rates."


According to the New York City health department, in the last four weeks, 26% of COVID-19 cases tested in the city have been the Delta variant.

Nearly 70% of adult New York City residents have received at least one dose of the COVID vaccine and nearly 64% are fully vaccinated.

There have also been many questions over whether a booster shot is needed to protect against the Delta variant.

"The bottom line is the vaccines work. They cover us against all of the current variants, so in the United States now, there is no need for a booster shot. Pfizer is filing the booster shot with the FDA in case we need it in the future, so we're lucky we don't need it at the present time," said CBS News medical contributor Dr. David Agus.

Agus said he's worried about the rise of the Delta variant in other parts of the world, like Africa, where the growth is exponential.

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