Connecticut residents 16 years and older became eligible for the COVID-19 vaccine starting Thursday.

The announcement was made last month after Gov. Ned Lamont said an increase in vaccine supply Connecticut hit about two months earlier than expected.

Lamont says over 100,000 people in Connecticut made appointments on Thursday. Many residents say they encountered flaws in the system while trying to sign up.

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One of the work-arounds state residents used to get appointments into CVS was changing their location on the website.

When you get into the CVS website, you will see all the appointments in Connecticut appeared to be fully booked. However, you can change your location to Alabama.

Once you click appointments in the Alabama system, you'll get a questionnaire to determine eligibility. At that point, you change your location back to Connecticut.

Yale graduate student Vlad Chituc made over nine appointments on Thursday. He says he turned to the Vaccine Angels group on Facebook, trying to find his classmate a vaccine who was high-risk when the CVS trick didn't work. He landed an appointment at a Yale New Haven clinic from answers in the comments.

Yale New Haven Health are giving people a leg-up who have high-risk conditions.

Chituc says he's confused why certain high-risk conditions are prioritized while others are not.

"You should not have the entire state of Connecticut with no real system trying to get the vaccine at once…scrambling on a million different websites," Chituc says. "It's just super confusing and I think a lot of people are kind of lost."

Some other tips for booking an appointment include checking for availability 10 minutes after midnight and checking with your local pharmacy for excess doses after 4 p.m.

The Pfizer vaccine is the only vaccine approved for 16- and 17-year-olds, so those looking to register will have to sign up at clinics that offer the Pfizer shot.

For those who fall into the 16 to 44 age group and have a serious illness like sickle cell disease, end-stage renal disease, are a cancer patient undergoing treatment, or a solid organ transplant patient, a doctor should be reaching out to them to schedule an appointment.

State officials say that around 1.3 million people are in the age group.