The U.S. Food and Drug Administration (FDA) recently approved Pfizer’s experimental coronavirus vaccine, prompting the pharmaceutical company to begin distribution across the country under its agreement with American officials.

On Thursday, Pfizer’s COVID-19 vaccine received authorization recommendation from the FDA’s panel of experts. The advisory panel was filled with independent scientific experts, infectious disease professionals, and statisticians. The group voted a unanimous 17-4 on giving emergency approval for the experimental vaccine while one member abstained from voting.

Federal officials said within the first 24 hours after approval of Pfizer’s coronavirus vaccine, the initial shipment of 64 million doses would be brought out of warehouses. About half of the doses would be spread across the United States, while the remaining half would be stored and used three weeks later as second doses for the initial recipients of the first batch.

The distribution of the COVID-19 vaccine is a coordinated plan involving federal and local health authorities, large hospitals, and pharmacy chains. Officials hope the treatment would help in bringing the country back to some state of normalcy by summer.

A senior vice president and the head of vaccine research and development at Pfizer, Kathrin Jansen, said during a meeting, “With the high efficacy and good safety profile shown for our vaccine, and the pandemic essentially out of control, vaccine introduction is an urgent need.”

Pfizer and its German partner, BioNTech, began the development of the COVID-19 vaccine about 11 months ago amid the growing threat of the pandemic. Other countries have approved the pharmaceutical company’s vaccine before the U.S., such as Bahrain and Britain on December 2, and Canada on Wednesday, The New York Times reported.

The FDA approved the use of the coronavirus for residents aged 16 or older, and the Centers for Disease Control and Prevention (CDC) recommended the prioritization of health care workers and residents of long-term care facilities. With the limit of supply of initial doses, states are challenged with the decision of who will receive the treatment first.

The chair of the CDC’s Advisory Committee on Immunization Practices (ACIP), Dr. Jose Romero, said that both priority groups were of “exceptionally high risk.” the medical professional voted earlier this month to include the two groups in the Phase 1a of the nation’s distribution plan.

Experts said that using the vaccine to keep doctors and nurses healthy is critical in the fight against the coronavirus. Romero previously said during an interview that any professional working in a health institution that is at risk of coming into contact with an infected patient should be vaccinated.

Residents of long-term care facilities such as nursing homes make up about 40% of the country’s coronavirus-related deaths.

The chief operating officer of the federal government vaccine initiative “Operation Warp Speed,” Army General Gustave Perna, said vaccinations could begin as early as 96 hours after initial approval by the FDA.

CVS said the December 21 was the earliest date that vaccine administration could begin inside facilities. The company has been preparing to conduct vaccinations in long-term care facilities. Spokesman Ethan Slavin said, “We’ll be in facilities that day in states that choose to begin as soon as possible.”

While the U.S. government secured 100 million doses from Pfizer’s coronavirus vaccine, two doses of the treatment is needed to achieve the desired 95% efficacy. However, officials could still make a deal to receive more doses of the vaccine.

With the distribution of the vaccines, the CDC has considered a four-phase plan and gives priority to essential workers at high risk of being infected, other emergency personnel, and people with underlying health conditions that are more susceptible to the virus.

The director of the National Institute of Allergy and Infectious Diseases, Dr. Anthony Fauci, projected that the first ones to receive the virus would include the high priority groups. He added, “I would project by the time you get to April, it will be ‘open season,’ in the sense of anyone, even the non-high priority groups could get vaccinated,” CNN reported.