Maryland officials will launch a one-stop, preregistration web portal soon for people looking to book COVID-19 immunization appointments at the state’s mass vaccination clinics.

The website would come online in March, the state’s acting health secretary Dennis R. Schrader told Maryland state senators at a virtual vaccine oversight meeting Monday.

“This is going to allow us to manage the flow of appointments, which we’re very excited about,” Schrader said. “But most importantly, we expect that establishing a preregistration system will improve the user experience and better prepare for the day when the supplies are very, very abundant.”

Schrader and Maryland Gov. Larry Hogan, a Republican, previously dismissed the idea of a one-stop registration website for vaccination appointments, calling it a setup for a “single point of failure.” But lawmakers, elected officials and members of Maryland’s congressional delegation have countered that the state’s largely decentralized system has created confusion and anxiety, excluding people not digitally savvy from signing up for time slots.

The new registration portal is only for the state’s mass vaccination sites. Appointments for doses from hospitals, health departments, pharmacies and others still would be scheduled separately.

Still, Schrader said it would help the state better coordinate with county health departments.

The state currently runs two mass vaccination clinics — one at Six Flags America in Prince George’s County and the other at the Baltimore Convention Center — with a third at M&T Bank Stadium scheduled to open Thursday.

The two sites combined have been inoculating thousands of people per day as the

available appointments fill quickly, sometimes within minutes.

Schrader said a newly launched phone line — 855-634-6829 — also has had success connecting users with appointments and information. The phone number is staffed with operators seven days a week, from 7 a.m. to 10 p.m., he said, and could help people register for appointments at mass vaccination clinics or help them find the closest provider to their place of residence.

Separately, the senators had hard questions for Schrader about what they referred to as a disparate vaccine rollout, which has come at the expense of people of color, low-income families and older adults. State data shows white people getting inoculated at more than four times the rate as Black Marylanders, a gap that has widened since the governor expanded eligibility to more people in January.

“If you do nothing else, it’s going to be worse. The disparity is going to get worse,” said state Sen. Mary Washington, a Democrat who represents Baltimore. “You see that evidence right in front of your face. ... The disparity is growing.

“You keep saying there’s vaccine hesitancy, but that’s really a blaming-the-victim approach, whereas the data says we need more 24-hour walk-up clinics. We need mobile units. We actually maybe need to reserve some doses for individuals who are slower to get in line.”

Washington asked Schrader for details about his team’s approach to “getting shots in the right arms.”

He acknowledged that he had not seen the vaccine-related demographic data she referenced, which Maryland’s chief innovation officer, Michael Powell, presented at the start of the meeting.

“Our data has shown that the African American distribution has held steady for the last eight weeks,” said Schrader, adding that that wasn’t necessarily a good sign. “Our numbers suggest there’s been a steady percentage across the last several weeks. Our goal is to increase that.”

Schrader said the agency was working closely with the state’s equity task force, which has been creating “linkages” in communities. He said more community events led by the state’s equity task force would take place next week, featuring the support of partners that include Johns Hopkins Medicine and the University of Maryland Medical System.

Democratic State Sen. Clarence Lam, a physician who represents Baltimore and Howard counties, asked Schrader for details about the state’s vaccine-related contract with the consulting firm Ernst & Young.

Schrader did not disclose the value of the emergency contract, but noted that the company was handling “a number of things” for the state, offering a national perspective on the supply chain and “helping us unravel some of the mysteries of the federal allocation and accounting system.”

Lam said that makes it even more crucial for the state to publicize the value of the contract and explain what the firm is doing.

“I would like to know what they are actually doing, because if they’ve been working with us the last couple weeks, it doesn’t look like our rankings have changed that much in terms of when you compare us to other states,” he said.

Meanwhile, several senators asked Schrader about Prince George’s County’s lagging vaccination rate, which ranked last out of all 24 counties in the percentage of population vaccinated.

“The No. 1 and 2 users of the mass vaccination sites are Montgomery County and Howard County, so we know that,” Schrader said. “However, as I said last week, we’re going to continue to press to get the population of Prince George’s County to get vaccinated. We’re not going to rest until we get those numbers up.”

Schrader meets every Monday with the Maryland Senate’s Vaccine Oversight Workgroup to monitor the state’s vaccination operations.

The information from the meetings will guide senators as they decide whether to confirm Schrader as state health secretary, Maryland Senate President Bill Ferguson, a Democrat, has said.