The home of the Mets opens at 10 a.m. Wednesday to provide vaccines.
Half the appointments are for Queens residents, and the other half are for food service workers and drivers licensed by the Taxi and Limousine Commission.
"No one bore the brunt more than Queens residents, Elmhurst and other neighborhoods. And the focus on food service workers and TLC licensed drivers. We do need to making moves that will encourage equity and address disparity, but it's all against the backdrop of fundamental lack of supply," de Blasio said.
The lack of supply means only 800 doses will be administered at Citi Field in its first week - 200 a day, Wednesday through Saturday.
The city and the state opened a vaccination hub at Yankee Stadium last week, administering more doses than currently slated for Citi Field.
"The state still controls the vaccine distribution," de Blasio said. "We're dealing as we have throughout this crisis with federal decisions, federal red tape, state decision, state red tape."
Governor Andrew Cuomo says the federal government is allocating more vaccines to New York, but supply will be limited until a vaccine from a third manufacturer is approved.
"The supply will really only increase when and if Johnson & Johnson is approved," Cuomo said. "The Pfizer, Moderna vaccines are ramping up, but the ramp-up is relatively slow."
Greater supply, de Blasio said, could enable Citi Field to vaccinate New Yorkers 24/7.
To help people travel there, the MTA announced that Long Island Rail Road trains on the Port Washington branch will stop at the Mets-Willets Point Station.
There will also be direct access to the stop from Penn Station, as well as Woodside.
Trains will run every 30 minutes during the day, and less frequently at night.
"It's very convenient it has connections to other modes of transportation as well but the Long Island Railroad is proud to be able to offer this," said LIRR President Phil Eng.