How Will the COVID-19 Vaccine Be Distributed?

All people 12 and older are eligible to receive a COVID-19 vaccine, and state and local health departments are determining how the COVID-19 vaccines are being distributed.

On March 11, 2021, President Biden announced that states would be directed to make all adults eligible for vaccination by May 1. On April 19, 2021, the Centers for Disease Control and Prevention (CDC) announced that all individuals 16 and older were eligible for a vaccine. Then, following the Food and Drug Administration's (FDA's) expansion of the emergency use authorization for Pfizer's COVID-19 vaccine, the CDC announced on May 12, 2021, that everyone 12 and older is eligible.

Prior to these changes in eligibility, each state set its own priority groups and timelines that partially followed a plan from the CDC.

The guidance for vaccine eligibility changed quickly and many kinks in distribution still need to be worked out, but experts tell Verywell it’s possible that life could be well on its way back to normal this summertime. 

“Assuming we still are good about masking and social distancing [and] we're able to meet the challenges of distribution and update, and assuming that there are no serious adverse events that occur...then slowly but surely, we should find a lesser and lesser degree of disease and hospitalization and death,” Paul Offit, MD, professor of vaccinology at the University of Pennsylvania’s Perelman School of Medicine, tells Verywell. 

How Was the Plan Introduced? 

The CDC plan, titled “Phased allocation of COVID-19 vaccines,” was presented at an emergency meeting of the Advisory Committee on Immunization Practices (ACIP) on December 1. This was two days after the biotechnology company Moderna requested an emergency use authorization for its vaccine from the Food and Drug Administration (FDA). (The agency granted an EUA for the Pfizer-BioNTech's vaccine on December 11 ,an EUA for the Moderna vaccine on December 18, and an EUA for the Johnson & Johnson vaccine on February 27. AstraZeneca has yet to request one.) 

While far from set in stone, the plan provided insight into what CDC leadership was thinking at a critical juncture in the pandemic. 

“Making adjustments as needed will definitely happen,” Offit says. “I think it's going to be a real learning curve here in the first few months until people get comfortable with how this is going to work best.” 

Developed by Kathleen Dooling, MD, MPH, a CDC co-leader of the ACIP COVID-19 Vaccines Work Group, the plan relies on a staggered model of vaccine distribution that adheres to several core ethical principles:

1. Maximize benefits and minimize harms
2. Promote justice
3. Mitigate health inequities
4. Promote transparency

The model was divided into several phases and subphases, but the plan focused mainly on Phase 1a, 1b, and 1c. This is likely because “limited vaccine supplies force ACIP to prioritize the vaccine distribution only to the populations identified in Phases 1 a, b, and c,” Zucai Suo, PhD, professor of biomedical science at the Florida State University College of Medicine, tells Verywell. 

Who Will Get Vaccinated When? 

Prior to expanding eligibility to the general public, all states followed the ACIP's guidance to put healthcare workers and residents of assisted living facilities (such as nursing homes) at the front of the line.

In about one-third of states, additional groups were eligible for vaccination in the initial rollout, diverging somewhat from the CDC's recommendations.

While in Phase 1, timelines and vaccine eligibility varied by state with some states adhering fully to the order of the ACIP's subgroups in Phase 1 and others diverging from it.

In the CDC's Phase 1a, those to receive the vaccine included:

• Healthcare personnel
• Long-term care facility residents

In the CDC's Phase 1b, which focused on frontline essential workers, those to receive the vaccine included:

• Teachers
• Firefighters
• Police officers
• Corrections officers
• Food and agricultural workers
• Public transit workers
• Teachers and school staff and daycare workers
• People ages 75 and older

The CDC stated that Phases 1b and 1c can overlap.

During the CDC's Phase 1c, the vaccine was made available to:

• Adults ages 65 and older
• People ages 16 to 64 with high-risk medical conditions, such as cancer, diabetes, obesity, cardiovascular disease, and chronic respiratory disease
• Other essential workers, such as transportation and logistics, food service, housing construction and finance, information technology, communications, energy, law, media, public safety, and public health

The target demographics were chosen based on their level of risk and their importance to the continued functioning of the economy and society. Long-term care facility residents, for example, accounted for the vast majority—40%—of all COVID-19 deaths as of November 2020.

According to the results of an online poll cited in Dooling’s report, the majority of American adults appeared to approve of ACIP’s recommendations, ranking healthcare workers and older adults as highest-priority and children and young adults as lowest-priority.

How Many Doses Are Needed?

Dooling estimates there are around 21 million healthcare personnel in the United States and 3 million long-term care facility residents. The plan does not provide an estimate for the number of people who will be vaccinated in Phase 1b or 1c, but Suo believes essential workers to number around 26 million people and older adults and immunocompromised individuals to number over 100 million people.

Suo's initial estimates for Phase 1a, which were based on the two-dose vaccines from Pfizer and Moderna, were that it would require at least 48 million doses; Phase 1b would require about 52 million doses and Phase 1c would require over 200 million doses for a total of roughly 300 million doses. Now that a single-dose vaccine from Johnson & Johnson is authorized and also commercially available, the total vaccine doses drop and should fall between 100 to 200 million for phase 1c, according to Suo's estimates.

Next Steps 

The companies that receive EUAs from the FDA will need to manufacture and distribute the number of required vaccine doses to clinics, hospitals, and pharmacies throughout the country and workers will need to administer them. 

But that is easier said than done. There are several barriers to distribution and administration, including but not limited to production rate and storage requirements. 

“[Phase] 1a, 1b, and 1c include probably about 150 million Americans," Suo says. In addition, he says, “the Pfizer vaccine has difficult storage, handling, and shipping requirements, because of the need for dry ice.”

On February 25, 2021, the FDA announced that the Pfizer-BioNTech vaccine could be transported and stored at regular freezer temperatures for up to two weeks. This update to the ultra-cold storage requirements may help with distribution.

The process of administration, according to Offit, will likely vary from locality to locality, depending on the proximity of “retail pharmacies” and “major hospital and university centers.” 

“For example, Philadelphia will probably handle it differently than a very rural, sparsely populated county in the center of the state,” he says.

Based on announcements from President Joe Biden and then the CDC, Phase 2 began in late April 2021. Now it's the general population’s turn to get vaccinated.

“For Phase 2, any American who is willing to be vaccinated will be eligible and likely be encouraged to take COVID-19 vaccine shots,” he says. 

The start of Phase 2 is also when Offit thinks local, state, and federal governments will begin to loosen some restrictions. But he cautions against thinking of the vaccine as a quick fix for the pandemic. Only once two-thirds of the population has been vaccinated, he says, will we be able to “really get on top of this virus.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.