The shift comes after the federal emergency management agency pushed for the vaccine to reach communities most impacted by the pandemic.
The agency shared that the first group of seniors who signed up at the United Center far outnumbered Chicago residents, prompting the change as reservations expanded Sunday to people under phase 1B plus.
Vaccine reservations opened up for people under 65, with qualifying jobs or health conditions at 4 p.m. on Sunday. However, available slots at the United Center quickly filled up, leaving many confused and disappointed.
Even Chicago residents are having issues signing up.
Bernie Ferro's daughter tried helping her make an appointment Sunday to no avail.
"I imagine there are a lot of people out there frustrated with this. Especially with the United Center," Ferro said. "They made this big thing so they could take more people and it is a headache to everybody."
ZocDoc, the website used to book appointments, went down when registration opened at 4 p.m. Sunday, then reappeared with changes asking people to confirm their location.
However, residents who live in the city couldn't book an appointment due to the crash and by the time it was back up, the slots were gone.
"She kept trying and then she gave up," Ferro said. "And she said, 'I will try tomorrow' and now I see the time slots are full."
Some who were able to book appointments got a cancelation notice if their address was outside the city.
Registration for more appointments at the United Center are expected to open up for Cook County residents in the coming days, according to officials.
The latest registration comes after Illinois set a new record in vaccinations administered Friday with more than 134,000 doses administered.
Before Sunday afternoon only people over 65 could register.
Despite the issues, starting Tuesday, 110,000 vaccine slots are scheduled to be administered at two United Center parking lots in what will be Illinois' largest mass vaccination site.
Ahead of the opening day, work continued to get everything ready. Nearly 200 Air National Guard Troops have been deployed from Kentucky to help run the site, even as vaccinations continue at smaller neighborhood centers around the city.
"I got a notification from my church, as a matter of fact, that they would be giving them out at the Golden Dome," said Theresa Hale, who got her vaccine Sunday. "I signed up. It went right through, gave me a date and gave me a time to come in."
Set up as part of the continued effort to get more seniors vaccinated, Garfield Park's Golden Dome served as the third of 11 neighborhood pop-ups scheduled over a 10-day period, with 500 appointments being offered up at each one. The campaign is being run by the City of Chicago in partnership with Jewel-Osco.
"That's really what this program is really. This series it's designed around is to try and get to those hard-to-reach seniors," said Candance Moore, Chief Equity Officer with the Chicago Mayor's Office. "It's going to be harder for them to get to the United Center, or they need someone to call and support them to get there-- so we're putting it right here in the community."
Unlike traditional scheduling systems, which can be confusing and frustrating for many, the city has partnered with community groups, churches and aldermanic offices to directly contact and register people for the pop-ups.
"I lost some friends and just to think about it today, it's still, you know, it's still harsh," said George Nunley, who also got vaccinated Sunday. "Like I said, I'm very happy and grateful."
Monday's pop-up is scheduled for the South Shore neighborhood. Those interested can email firstname.lastname@example.org to sign up.
Aurora will also host a mass vaccination clinic Monday in partnership with Jewel-Osco and the Kane County Health Department. This will be the second time in a week the suburban city has held a clinic.
The Aurora mass vaccination clinic will open at 8 a.m. Monday at the former Carson Pirie Scott building located at 970 N. Lake Street on the city's west side.
The clinic will provide the first dose of the Pfizer vaccine to 2,400 qualifying people who pre-registered, however, officials said capacity was reached in less than six hours.
The city outfitted the upper level of the vacant 181,000 sq. ft. former Carson Pirie Scott store to serve as a standing mass vaccination site. It will be used as vaccines become more readily available to residents who are in the current priority categories, officials said.
Under the city's Mass Vax Aurora banner, the Aurora mayor plans to announce additional mass vaccination clinics with other partners as early as this week. Information will be posted at www.MassVaxAurora.com.
As for the United Center, shots will be given out starting Tuesday.
The United Center will be the largest vaccine site in the state.
To register for an appointment at the United Center, visit www.zocdoc.com/vaccine or call the multilingual hotline (312) 746-4835 from 8 a.m. to 8 p.m. Monday through Saturday and 8 a.m. to 4 p.m. on Sunday.
Those seeking appointments can also check for available slots in Southern Illinois by visiting https://jchdonline.org/.