NEW YORK (CBSNewYork) — The urgency for vaccinations is greater than ever as the CDC warns the highly contagious U.K. variant of COVID could dominate the U.S. by spring.

Meanwhile, New York City is opening more vaccination sites, including one in Harlem on Sunday, but it’s still a challenge for many to actually get the shot, CBS2’s Christina Fan reported.

READ MORE: Police Reveal More Details In Death Of 10-Year-Old Ayden Wolfe; Mother's Boyfriend Ryan Cato Faces Murder Charges

The Brooklyn Army Terminal mega vaccination site was locked up tight Saturday. It was supposed to be open 24/7.

Imagine the surprise of public school teacher Kaitlyn Palombo when she arrived.

“I had an appointment today,” Palombo said.

“Unfortunately, this site is closed today so everyone was rescheduled,” she was told by an official there.

COVID VACCINE

“They said that they’ve been rescheduled, but I’ve not been notified,” Palombo told CBS2. “It’s extremely frustrating, the lack of information and transparency.”

“We thought we were all set. We got confirmation,” said Mike Morley of Carmel, New York.

Morley learned the four appointments for him; his wife, a special needs teacher; and two relatives in their 80s, disappeared. So, he was forced to start the process over.

“We have spent day and night since Wednesday (Jan. 13) trying to get an appointment,” Morley said. “All we want is to be able to make an appointment.”

But as supplies dwindle, more vaccination sites are opening.

READ MORE: Long Island Rail Road Riders Face Crowded Trains On First Day Of Service Cuts

CORONAVIRUS PANDEMIC

A new location at the Polo Grounds Senior Towers in Washington Heights started administering shots Saturday morning.

Juan Rivera, 65, was surprised he was able to schedule an appointment on the spot after he heard about dwindling supplies.

“I was expecting to go back home to wait a couple of days, or maybe a week, or I don’t know,” Rivera said.

MORE: COVID Vaccine: More Distribution Sites Open Across NYC While New Yorkers Say Appointments Are Vanishing, Being Rescheduled

Three centers in NYCHA complexes opened this weekend to vaccinate the city’s older and disproportionately affected populations.

So far, it’s clear the demand for vaccines is outpacing the supply. Mount Sinai Hospital, for example, had to cancel appointments last week.

There are more than 7 million New Yorkers currently eligible for the vaccine, but the state is only scheduled to receive about 250,000 doses from the federal government this week.

Mayor Bill de Blasio made the dire prediction that doses of the vaccine could run out in the coming days.

CBS2’s Christina Fan contributed to this report.

MORE NEWS: NYPD Making Progress Bringing In And Promoting Women, But It Still Has A Lot Of Work To Do

MORE FROM CBS NEW YORK:

CBSNewYork Team