Nearly 4 million doses of the Johnson & Johnson vaccine are shipping out around the U.S. after getting the green light over the weekend.

New York is expecting 164,000 initial doses of the vaccine, but just how quickly those doses will land at your doctor's office or pharmacy is up in the air.

Suffolk County says it has a standing order for all vaccinations. And Nassau says it will be requesting it.

At Family RX Pharmacy in East Meadow, it could still be several weeks before a vaccine is in stock. But pharmacist Max Yunat says there is definitely a lot of interest.

"People are insistent. We get at least 50 to 100 calls a day requesting vaccines. But unfortunately because we don't have any and don't know when we're getting them so we can't schedule appointments yet," says Yunat.

Doctors say with three vaccines approved, a common question is if you can choose which you get. They say you cannot, and you'll get whichever vaccine is being used at wherever you make your appointment.

And the general advice is to get what you can get.

"We want to get as many people vaccinated as quickly and as expeditiously as possible," says Dr. Anthony Fauci.

Johnson & Johnson's CEO said in a statement, "Our goal all along has been to create a simple, effective solution for the largest number of people possible, and to have maximum impact to help end the pandemic."