Chicago was already accepting walk-ins at all of its city-run sites. You can show up and register on-site, but appointments are still recommended.
Sites in Tinley Park and Matteson has already started accepting walk-ins last week. They are now joined by sites in Des Plaines, Forest Park, River Grove and South Holland. Walk-ins are accepted from 8:30 a.m. to 5 p.m. Monday through Saturday.
For those still having trouble scheduling that second dose at their original location, Cook County vaccination sites will take any Illinois resident on a walk-in basis to get their second shot. Just make sure to bring your CDC card and verify that the location you want to go to offers the vaccine you need to complete the set.
Appointments can still be made at vaccine.cookcountyil.gov or by calling 833-308-1988, Monday - Friday from 7 a.m. - 10 p.m. and Saturday from 8 a.m. - 10 p.m.
Now people like Vito Messa from Norridge can simply walk into the Triton College site, register and get his shot on the spot.
"It's way convenient because like I said, I just passed by here so I didn't have to go out of my way to stop," Messa said.
Don Christiansen has had trouble scheduling his second shot. His whole family has been trying to help him find one close-by.
"I live in River Grove now," he said. "I'm 69 years old and it's been a pain in the butt to get a shot around here."
RELATED: Miss your 2nd COVID vaccine dose? Supply, expanded eligibility, vaccine hesitancy may be to blame
But health officials are now worrying about a growing trend: as more and more people seem to be missing out on getting their second dose.
More than half of all American adults have now gotten at least one shot of the COVID-19 vaccine and we're nearing a point where supply will outweigh demand. But there are new concerns, as the CDC released data showing that more than 5 million people have not gotten their second dose within the allotted time frame.
"The biggest problem is their immunity will wane faster, so we don't really know how long it lasts because we're not studying people who only got one shot," said Dr. Richard Novak, University of Illinois Health.
Dr. Novak led UI Health's Moderna and J&J vaccine trials in Chicago. He says, historically, it's been a challenge to get people to come in for booster shots of multi-dose vaccines. From that perspective, the existing 92% completion rate is considered quite good. And the number might be even higher.
"There are people who got their first shot in one location and in one type of location, let's say, a local health department. and they went and got their second shot at, let's say, a Walgreens. And as a result, at least initially, it's hard to reconcile that," Gov. Pritzker said.
Officials say there are a multitude of reasons why people may not be getting their second shots on time. Ranging from trouble scheduling and mix-ups like those reported at Walgreens nationwide, where people have been inadvertently sent to locations that do not offer the vaccine they need, to fear of side effects. Or even a mistaken belief that they have enough protection with just one dose.
"It's true the second dose has some side effects, but the whole point of getting vaccinated is to protect you from COVID and if you don't get both doses, your risk is still there of getting COVID," Novak said.
For Sherri Smith, who got her second dose on Monday, it just made sense.
"If you've had the initial shot, wouldn't you want to finish it? It's like going to Driver's Ed and you've taken the entire course, but now you don't go in and get the road test," Smith said.