Gov. Larry Hogan on Monday rejected a demand by congressional Democrats for a “course correction” on Maryland’s COVID-19 vaccination program and touted — during tours of two Baltimore-area vaccination sites and a vaccine plant — the state’s readiness to distribute an increased supply.

Maryland’s current course has brought the state “from 2,000 shots per day to over 22,000 shots per day in a matter of weeks,” Hogan wrote to the Democratic federal lawmakers from Maryland who last week called on him to improve the state’s vaccine rollout. The Republican governor suggested congressional staffers spend more time reviewing relevant federal vaccine policies and briefing their bosses, “as opposed to writing press releases disguised as letters.”

“We will not rest until every Marylander who wants a vaccine can get a vaccine,” the governor wrote. “You can be a part of this incredible undertaking, or you can criticize it from the cloakroom.”

Hogan spent Monday greeting people getting vaccines at the Maryland State Fairgrounds in Timonium and the Baltimore Convention Center. He also visited Emergent BioSolutions in East Baltimore, where workers are making millions of doses of the still-unapproved Johnson & Johnson and AstraZeneca vaccines.

A shortage of vaccines has vexed officials across the country, and President Joe Biden has set a bench mark to deliver 100 million shots in his first 100 days in office. Maryland is asking the Biden administration nearly every day for updates on when more vaccine will be available, Hogan said.

“They’re pressing the two manufacturers and trying to figure out everything they

can to increase production,” he said. “They have promised to do so. But they don’t have specific numbers or time frames.”

The difficult process of securing a vaccine appointment has prompted frustration for many in Maryland, Hogan acknowledged.

“‘Why can’t we get scheduled for a vaccine?’ Well, we’re waiting for more vaccines,” Hogan said. “That’s the basic issue.”

But he stressed that the state is “building an infrastructure that’s going to be able to handle every single one they give us. We’re going to be able to get people vaccinated just as soon as we get more supply.”

Hogan said he expects Johnson & Johnson’s application for federal emergency-use authorization for its vaccine to be approved by the end of the month, allowing some of the millions of doses being made at Emergent BioSolutions, near Johns Hopkins Bayview Medical Center, to be distributed.

Johnson & Johnson has contracted with the Gaithersburg-based company to manufacture 1 billion doses of its one-shot vaccine.

The governor walked through the facility, thanked employees and grinned as Emergent BioSolutions general manager James Glover received his first dose of the Moderna vaccine from Rite Aid pharmacist William Ireland in a makeshift clinic for the lab’s employees in a conference room.

“You guys have made such progress, and hopefully we’re going to get some [emergency use authorizations], and we’ll be able to start utilizing these vaccines, and it’s going to help us tremendously,” the governor told the workers.

The Baltimore Convention Center, a field hospital jointly operated by Johns Hopkins Medicine and the University of Maryland Medical System, planned to administer 400 doses Monday after giving just 100 doses on its first day of inoculations Friday. Vaccinations are available by appointment only from 8 a.m. to noon; walk-up testing is offered from 2 p.m. until 6 p.m. on weekdays.

The Baltimore Convention Center eventually will be able to distribute as many as 10,000 vaccines per week.

“We have a capacity to do 1,500 a day,” said co-director Dr. Jim Ficke of the Johns Hopkins School of Medicine.

The state fairgrounds in Timonium planned to give out 2,000 doses in four hours Monday but could easily ramp up from that once additional vaccines arrive, Baltimore County Health Director Dr. Gregory Wm. Branch told Hogan. More than 10% of the county’s population have gotten their first doses.

The Baltimore County site could be expanded as one of the state’s mass vaccination sites, Hogan said during his visit.

“I know that they could do a lot more capacity,” Hogan said.

Hogan said the fairgrounds’ Cow Palace building already was operating as a “mass vax site for Baltimore County,” but once vaccine supplies increase, “we’d love to work together with them” on expanding it as a state mass vaccination site.

Elyn Garrett-Jones, a Baltimore County health department spokeswoman, said there haven’t been any official discussions with Hogan’s administration over whether the fairgrounds will be converted to a state mass vaccination clinic, but the county is ready to have those talks.

Any Maryland resident could be vaccinated at any of the six mass vaccination sites once they are all operating, as long as they fall into a group that is currently eligible for the vaccine.

Those who managed to secure an appointment Monday said getting the shot was comparatively easy.

Patients vaccinated at the fairgrounds were ushered into the parking lot by police and parking attendants. Inside the Cow Palace, they showed a driver’s license or other form of identification and answered questions to determine their risk of vaccine reaction.

After being vaccinated, patients waited 15 minutes in a socially distanced area in the center of the Cow Palace, which accommodates up to 12,000 people in its 158,400-square-foot space.

Trina Hough wasn’t sure, at first, whether she was going to sign up for the vaccination. The advanced radiologist, who lives in Rosedale, planned to wait, feeling confident in her immune system and being in a lower-risk category for coronavirus complications.

But when the 47-year-old started seeing the coronavirus killing people her age, she decided to get one. On Monday she received her second dose at the Cow Palace after her employer set up her appointment.

Hough was thinking of her patients, many of whom are battling cancer, and “doing everything they can, taking any kind of treatment to stay alive,” she said. She wanted to do the same.

At Emergent BioSolutions on Monday afternoon, Sean Kirk, the company’s executive vice president of manufacturing, thanked Hogan for ensuring the plant’s staff were prioritized for vaccinations. While the Johnson & Johnson vaccine is not yet federally approved, Rite Aid was providing the Moderna one to staffers.

“These 300 individuals are responsible for producing hundreds of millions of doses of lifesaving vaccine,” he said. “It means the world to us.”