WILMINGTON, Delaware (WPVI) -- Health officials in Delaware say more than 8,000 initial doses of the Pfizer BioNTech COVID-19 vaccine will be distributed in the coming days.
Upon Delaware's receipt of the vaccine, which is required to be kept at below-freezing temperatures, health care systems will be able to begin vaccinating their frontline employees within 24 hours.
"The arrival of the Pfizer vaccine is welcome news after nine long months fighting COVID-19," said Governor John Carney. "This vaccine will help protect our health care workers who are working day and night to care for the sick and save lives. But we are not in the clear yet. We are still in for a very difficult winter."
The vaccine will be distributed in three phases:
Phase 1a: Health care personnel, emergency medical services agencies, and long-term care staff and residents will receive the vaccine first.
Remainder of Phase 1: In early 2021, those who work in high-risk and critical infrastructure industries such as food processing, utilities, education, police and fire, those who work and live in congregate settings such as correctional facilities and homeless shelters, as well as those with certain underlying health conditions, and are aged 65 and older are likely to receive the vaccine.
Phase 2: (March 2021) Those with more moderate-risk for getting COVID-19 are eligible for receiving the vaccine. More details about specific groups in this phase will be provided as we get closer.
Phase 3: (Spring/Summer 2021) The general public can expect to receive vaccines through their primary health care providers, health centers and pharmacies as the vaccine becomes more widely available.
The Food and Drug Administration late Friday authorized Pfizer's COVID-19 vaccine for people ages 16 and up, but warned that those with known severe allergic reactions to any of the vaccine's components should avoid taking it.
But this begs the question -- what is in the vaccine?
The good news is that Pfizer's mRNA vaccine doesn't contain any known allergens like eggs or metals.
In fact, to allergy experts, most of the ingredients don't raise any alarm bells. Pfizer's vaccine has genetic material known as mRNA, as well as fats, salts and other ingredients commonly found in everyday medications that help maintain stability.
Because we already have mRNA in nearly every cell of our bodies naturally, it's harmless, experts explained. The lipids, or fat lobules, and salts found in the vaccine add stability and structure to the mRNA and also help the mRNA slide into our cells. This way, our immune system's cells can appropriately respond and learn to attack the virus when exposed to it naturally in the real world.
There is only one ingredient in the vaccine, called PEG, that could potentially cause an allergic reaction, but experts agree it is unlikely to be a problem for the vast majority of people.
PEG "is a very common inactive ingredient found in a lot of over-the-counter things and in a lot of injectable medications," Dr. Erin L. Reigh, a staff physician in the Section of Allergy and Clinical Immunology at Dartmouth-Hitchcock Medical Center, told ABC News.
"I have seen a few cases of allergies to this in my career, but it is very rare," she added.
ABC News contributed to this report.