Doses of Moderna's coronavirus vaccine are expected to start arriving on Long Island at the beginning of next week.

The Food and Drug Administration authorized the Moderna vaccine for emergency use on Friday.

Around 6 million doses of the vaccine will be shipped out across the country with New York State set to receive 346,000 doses.

That number is around double the amount of the Pfizer vaccine that came in this week.

Moderna's vaccine is similar to Pfizer's in that they both are messenger RNA vaccines, and both require two doses.

However, the Moderna vaccine does not need to be kept as cold as the Pfizer vaccine. This will give health care provides an easier way to store it.

East Meadow pediatrician Dr. John Zaso says the Moderna vaccine could wind up in doctors' offices and pharmacies in the near future.

"It vastly increases the amount of people that can get it easily. The Moderna vaccine can be kept in refrigerator temperatures, whereas the Pfizer vaccine needs a deep freeze," he says.

Another difference between the two vaccines is the number of doses that will be available right away.

In its first shipment, Pfizer delivered 170,000 doses to New York state. Moderna is expected to send around 346,000.

Dr. Onisis Stefas, Chief Pharmacy Officer at Northwell Health, says shipments of the Moderna vaccine could arrive as soon as Monday.

He says this is welcome news after the health care system recently learned there won't be another Pfizer delivery for about two weeks.

"Based on the current shipment we received, we don't have enough to vaccinate all of our front-line healthcare workers, and that's why the addition of the Moderna vaccine is going to be extremely helpful with that," Dr. Stefas says.

States across the country say their Pfizer deliveries were suddenly cut. In a statement, the company said it has millions more doses sitting in a warehouse, but they have not received shipment instructions.

U.S. Army Gen. Gus Perna with Operation Warp Speed says the confusion was caused by a communication mistake, and he blamed himself.

The Pfizer and Moderna vaccines use similar technology, and they both require two injections.

Both vaccines are around 95% effective, as reported by clinical trials.