DALLAS (CBSDFW.COM) – Teresa Mata admits she was nervous and undecided until the last minute about whether to get Pfizer’s COVID-19 vaccine.

But, Mata, a mother of four who cleans rooms at Methodist Dallas Medical Center’s Emergency Department, ultimately walked away feeling great.

“They told me I’m the first person to receive the vaccine. So… woohoo!” she said.

More than 100 employees for the Methodist Health System received their first doses of the vaccine Monday, Dec 14.

Another 500 are expected to get theirs over the next two days.

“It’s an emotional and exciting day. We’ve been dealing with this since March taking care of the sickest patients here,” said Dr. Zachary Dreyfuss, an ICU physician.

The 5,850 doses Methodist received Monday morning were the first to arrive in North Texas, outside of clinical trials.

Three more hospital systems – Parkland Health, UT Southwestern, and Texas Health Resources in Fort Worth – are scheduled to receive the same number on doses Tuesday, Dec. 15.

Parkland says, depending on what time its shipment arrives, it could vaccinate as many as 500 employees on the first day, starting with frontline nurses.

“This is the first time in a long time I’ve felt giddy. I felt excited and optimistic. And I think that’s a general sense with many of us in healthcare because it’s the first time we’ve actually had something that we know will make a meaningful impact in transitioning us back to normalcy,” said Dallas Medical Society President Dr. Mark Casanova.

Casanova sits on a Dallas County advisory committee, offering detailed guidance on who should receive the vaccine first. He expects the pace of vaccinations will quickly increase.

More than a dozen additional North Texas hospitals are set to receive smaller batches of the vaccine by the end of the week.

As early as next week, the Texas Department of State Health Services says it’s prepared for Moderna to begin deliveries of its vaccine.

Doctors warn it will be months before the general public has access, but the Monday’s vaccinations marked a significant first step.

“There is light at the end of the tunnel,” said Dr. Dreyfuss.