By Dana Kozlov

CHICAGO (CBS) — Drug giant Pfizer asked the FDA on Friday for approval to give its vaccine to 12-to-15 year olds in the U.S.

Pfizer’s vaccine is already approved for people 16 and over.

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The Pfizer news comes at the same time Illinois is opening vaccine appointments to everyone in the state, age 16 and older, but it means millions more people will now be scrambling to get them.

CBS 2 Political Investigator Dana Kozlov reports from a state mass vaccination site in Des Plaines that there are concerns it could again jam up the appointment system.

CBS 2 is still hearing from people who, up to this point, have been unable to get an appointment. So add millions more to the pot and frustrations could reach a boiling point, again.

Sites like the one in Des Plaines one have been busy all day, but the good news is as demand goes up, there are signs supply will go up too.

The relief is palatable.

“Relieved that I can go out do some shopping in the malls, do some restaurants and meet friends,” said one man getting his shot.

People getting their second, even their first COVID vaccine shots in Groups 1A, 1B and 1C feel the weight of isolated living lift almost immediately.  Beginning Monday, that relief will extend to everyone in Illinois age 16 and over.

That means millions scrambling to book those appointments.

“I’m concerned that time interval is going to go down again.”

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Vaccine Angel administrator Susie Prather is talking about the time from when a vaccine appointment opens up to when someone books it.

Initially, Prather said those spots would be snapped up within two minutes. Recently, many stayed open for up to 20 minutes.

So what advice does she have for those looking to book a shot soon?

“Not to sound like a broken record, but they should go on Chicago Vaccine Hunters Facebook page.

That’s because Prather said appointment variables, like when they tend to drop at Walgreens or Walmart, or the like, keep changing.  And she said hotlines are very helpful too. But in Cook County’s case, its hotline recording is outdated.

Because Cook County appointments have been available to all Illinois residents for almost a month, and now to all groups.

“I’d really like that to change, so people don’t get confused,” Prather said.

The good news is supplies keep going up. And as of Thursday, the state reports 73% of all senior and 42% of Illinoisans age 16 and up have already gotten one dose. Twenty-five percent of the state’s population is fully vaccinated.

People who are 16 and 17 who live in the city cannot get a COVID vaccine in the city of Chicago until April 19. But they can go to mass vaccination sites around the state.

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Another thing concerning Prather is trying to find ways to help those who are homebound who cannot get out to get a vaccine. She said she hopes to see more programs in place to help them get vaccinated.