If you’re at least 65 years old and still looking for a COVID-19 vaccine, set your alarm for Thursday morning.

Bookings for appointments at the United Center mass vaccination site open up at 8:30 a.m. on March 4 via Zocdoc.com/vaccine and at 312-746-4835. People are required to enter their birth date to confirm they are at least 65 years old.

The United Center will be run by the Federal Emergency Management Agency and will officially open for actual COVID-19 inoculations on March 10.

Chicago’s Public Health Commissioner Dr. Allison Arwady says there will be about 110,000 appointments available when registration opens and those slots will be for the first dose of the Pfizer COVID-19 vaccine.

“If you know somebody, if you have a neighbor, if you have an aunt, if you have someone you know who’s over 65, who hasn’t been vaccinated, please do that outreach right now and say, ‘Can I help you make that appointment?’” Arwady said.

If those slots are not all booked by people 65 and older, Zocdoc and the call center will start booking anyone who is eligible under current state guidance starting at 4 p.m. on Sunday, March 7.

The state has allowed people aged 16 to 64 with underlying conditions to begin being vaccinated, though the city and Cook County have held back opening up appointments to those people. However, that group will be allowed to book appointments at the United Center, if they are available after seniors get first dibs.

Chicago residents can also get a free ride to the United Center through Uber. The city has partnered with the ride-sharing company to provide 20,000 $40 credits to eligible residents.

Becky Vevea covers COVID-19 vaccines and city politics for WBEZ. Follow her @beckyvevea.