The Grand Central site is among eight operating at train stations across the city, Long Island, and in Westchester County, with Johnson & Johnson vaccines available for all walk-ins.
The goal is to make it as convenient as possible for residents, commuters and even tourists.
The MTA is also offering a free seven-day MetroCard or round-trip LIRR/Metro-North ticket as an incentive.
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MTA Chairman Pat Foye was on hand for the ribbon cutting of the new site in Vanderbilt Hall, and he said if the pilot program is successful, it could be extended.
Meantime, the city is gearing up to offer the Pfizer vaccine to kids ages 12 to 15 beginning Thursday, pending the authorization.
Teens in the new group will have to have parental permission, either in person, over the phone, or via a written form.
"We have a plan to reach young New Yorkers and get them vaccinated," Mayor Bill de Blasio said.
Appointments are recommended, although walk ins are still permitted.
"If all goes according to plan, the city will offer the vaccine to New Yorkers 12 to 15 at multiple sites all across the city, another hopeful milestone in our battle against COVID-19," Health Commissioner Dr. David Chokshi said. "There are over 250 sites on the vaccine finder that administer the Pfizer vaccine, including some of most iconic locations like the American Museum of Natural History, Citi Field and Empire Outlets, along with other city hubs, Health+Hospitals facilities, mobile sites, community clinics, and dozens of pharmacies across the city."
De Blasio also announced gift cards for vaccinations.
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