Dr. Anthony Fauci revealed on CNN, Sunday night, that Moderna’s anticipated COVID-19 booster shot will not be available the week of September 20 as had been previously announced. He added that, as for Pfizer, “things look like they’re ready to go.”

“I don’t think that is a major issue there, but we would have liked to have seen it happen all together, simultaneously. But ultimately the plan will be implemented, as was put forth,” Fauci told CNN’s Jim Acosta. He added that Moderna could be ready a week or two later.

Fauci, Vaccine, BoosterPool / Getty Images

Fauci also spoke about the prevalence of the Delta variant in the United States: “What we’re observing now – not only here in the United States but in other countries, including Israel and the UK – [is] that the durability of the protection tends to wane, particularly in the context of the Delta variant,” Fauci said

Fauci went on to use the success of the booster shots in Israel as an example of how much good they can do. He says the country is “a month or so” ahead of the U.S. and their booster data shows a “substantial diminution in protection against infection and an unquestionable diminution in the protection against hospitalization.”

“Importantly, their data also show that when you give those boosters you reconstitute, to an even higher level than before, the protection against both infection and hospitalization,” Fauci explained. “The boosters really jack up the response very, very high, and we hope that that response would be durable.”