By Steven Graves

CHICAGO (CBS) — You may have to wait longer than first thought to get your COVID-19 booster shot.

The September 20th rollout is now in question for millions of people. CBS 2’s Steven Graves spoke with doctors about the looming change in plans.

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September 20th. That is when President Biden hoped the booster shots would go into more arms. But now federal officials are saying more time might be needed if you get the Moderna shot.

For those who got two COVID-19 shots, a third may sound enticing. With the Delta variant case count rising, concern is as well.

“Especially healthcare workers, as we were the first to be vaccinated. It’s been nine months.”

Doctor Susan Bleasdale is an infectious disease doctor at University of Illinois Health. She said the rush to get the additional shot, for them, is a waiting game. Even as they see more mild breakthrough cases in vaccinated people.

“We need to be very rigorous in how we look at information. And not make decisions until we have complete data sets to make that appropriate decision,” Bleasdale said.

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As the Food and Drug Administration is expected to clear Pfizer for a third shot, Moderna announced Friday it has just completed its submission. Federal officials are now worried Moderna data might take time. And that President Biden’s September 20th start date is ambitious.

But Doctor Anthony Fauci is confident a third dose will be recommended. He spoke recently about the benefits that came out of an Israeli study.

“The boosts that are now being done there and contemplated here support very strongly the rational for such an approach based on the very favorable data associated with boosts,” he said.

In Chicago, Doctor Bleasdale continues to push the vaccine and and other mitigations like masking. And hospitalizations still consist of largely unvaccinated people. She said the key to boosting vaccine progression remains in studies that she’s confident will be done thoroughly.

“That’s really important with a lot of the hesitancy and questions about vaccination in the speed of which vaccinations have become available. So we have to stick to our processes,” Bleasedale said.

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Both the Centers for Disease Control and FDA have already approved third doses in immunocompromised people. No decision on the Johnson & Johnson one-dose shot has been made.