SkyEye flew over the sprawling complex where rows and lines of vehicles were being funneled into vaccination stations underneath white tents.
The opening of the vaccination drive-by clinic wasn't without some hiccups. A number of factors, including missed appointments throughout the day, forced some people to wait for up to 45 minutes. FEMA told ABC13 it is working to resolve the long waits.
The clinic had a soft launch Tuesday and will provide another site in addition to the county, city, hospital and pharmacy locations throughout the region.
Organizers say at a minimum, the federal site is expected to vaccinate 126,000 people. An estimated 300,000 people who have signed up for the vaccine are still waiting for their first vaccine dose. The mega site should greatly increase chances of getting the shot soon.
On Monday afternoon, Harris County Judge Lina Hidalgo, Houston Mayor Sylvester Turner, FEMA regional director Tony Robinson and other local authorities gave details of the federally-supported, state-managed COVID-19 mass vaccination clinic.
WATCH: Glimpse at NRG Park COVID-19 vaccine mega-site ahead of soft opening
Since its announcement a few weeks ago, workers have been building the temporary mass vaccination facility. It will be a drive-through facility in the Yellow Lot at NRG Park.
"People deserve some good news, some hope," Hidalgo said. "This site marks the biggest effort to date to get our community vaccinated."
According to Hidalgo, they will be vaccinating those who live in the zip codes hit hard by the virus.
"All of us at the state, federal and local level, we're in agreement that this site has to focus on the folks who've been left behind so far, who've been hit the hardest by COVID-19," Hidalgo said. "We've done it by finding zip codes with the highest incidence of the virus, and the highest social vulnerability and the social vulnerability index."
The zip codes are the following: 77022, 77029, 77032, 77078, 77087, 77093, 77502, 77504, 77506, 77587, 77011, 77012, 77015, 77016, 77020, 77026, 77028, 77033, 77037, 77038, 77039, 77048, 77086, 77091, 77503, 77060, 77080, 77099, 77013, 77014, 77036, 77050, 77051, 77076, 77090.
Hidalgo added that the individuals 65 and older on the waitlist who come from the city's and the county's top 10 zip codes will receive top priority for the vaccines on the site.
The next priority group will be those people who are 65 years and older.
"Then we will prioritize individuals next from the rest of the 25 hardest-hit zip codes before pulling from the broader waitlist," Hidalgo said. This group will be those 60 to 64 years of age with underlying medical conditions living in high risk zip codes.
The fourth priority group will be those 60 to 64 years of age with underlying medical conditions.
FEMA is using the waitlist from Harris County and the city of Houston. Individuals are being contacted for appointments.
To join the waitlist for the city of Houston, visit their website at houstonemergency.org/covid-19-vaccines or call 832-393-4301.
Harris County's waitlist can be reached at vacstrac.hctx.net.
Follow Miya Shay on Facebook, Twitter and Instagram.