This week, Arizona celebrated the milestone of more than 1 million doses of vaccine administered by the state, counties and health care providers. While this is a significant achievement, vaccination sites have capacity to vaccinate even more Arizonans if additional vaccine doses are made available by federal partners.

Since Arizona is a “home rule” state for public health, ADHS utilizes a local allocator model to allocate doses to 15 counties and four tribal partners based on population estimates for the current priority groups. To date, vaccine doses and supplies have been allocated pro rata based on U.S. Census and Bureau of Labor Statistics data and other reliable sources, including estimates of the number of healthcare workers, education and childcare, protective services workers, and those age 65 and older.

As has been the case since the beginning of vaccine distribution, Arizona and other states receive confirmation of the total allocation of doses from the federal government on a weekly basis. This short-term outlook on total available doses makes it challenging to make long-term plans about vaccination events and the number of people who can be vaccinated each week. State and local partners generally receive a one to two-day notice to be able to place orders in time for vaccine to arrive at sites for the following week. We’ve heard recently that states will be provided a three-week outlook on the number of doses, although these recent projections may not be guaranteed since weekly production quantities are subject to change. 

Like many other states, each week Arizona continues to be disappointed by low weekly vaccine allocation and has submitted multiple federal resource requests for more vaccine doses and ancillary supplies to be able to meet demand.

Arizona is currently receiving two types of vaccine: Pfizer and Moderna. Both of the vaccines require an individual to receive two doses in order to be fully protected. Moderna is a more stable vaccine presentation and has been prioritized for rural communities. Currently, the two state-operated vaccination sites in Maricopa County are administering Pfizer vaccine only. Due to the fragile storage and handling requirements of the Pfizer vaccine, it has been prioritized for sites that have ultra-cold storage such as the State Farm Stadium and Phoenix Municipal Stadium PODs. The third state vaccination site in Pima County will transition to Moderna vaccine over the upcoming weeks. As the state considers expanding state vaccination sites through other Arizona communities, we recognize the importance of making vaccines available to all Arizonans in rural and suburban communities. The state vaccination sites remain open for all Arizonans in 1A and 1B priority groups, ensuring access to vaccination for those across the state.

For Arizona, the allocation uses the process below to determine the initial amount the counties will receive.

First, it is important to note that the allocation for some federal programs, including the CDC Pharmacy Partnership for Long-term Care that serves our most vulnerable residents, comes off of the top of the state’s allocation. Both first and second doses are automatically deducted from Arizona’s weekly allocation total based on the needs of the long-term care program. This program provides vaccinations to residents and staff at about 2,000 eligible facilities throughout the state of Arizona.

Next, counties are assigned second doses to match the number of first doses from the corresponding previous weeks when the federal allocation allows. For Pfizer, the number of first doses from three weeks prior are allocated. For Moderna, the number of first doses from four weeks ago are allocated to the appropriate jurisdictions. 

Then, the number of first Pfizer doses are determined. These are divided based on need for the following entities: state vaccination sites, Maricopa County, and Pima County. The Pfizer doses for Maricopa County consist of doses allocated to State Farm Stadium vaccination site, Phoenix Municipal Stadium vaccination site, and Maricopa County vaccination sites. Moving forward, the Pima County allocation will consist of doses allocated to Pima County and the University of Arizona vaccination site as they complete the transition to Moderna vaccine. Due to the limited number of vaccines allocated to the state, the allocation is adjusted based on availability of vaccine and information reported per Executive Order 2021-01.

The number of first doses is determined for each county using the following formula, with percentages currently based on their pro-rata population of the 1B phase.

Total 1st doses = [(# of Moderna 1st Doses) + (# of Pfizer 1st Doses)]

For the Moderna vaccine:

  • Apache: 0.011 x (total # of 1st doses) 
  • Cochise: 0.020 x (total # of 1st doses) 
  • Coconino: 0.016 x (total # of 1st doses) 
  • Gila: 0.010 x (total # of 1st doses)
  • Graham: 0.006 x (total # of 1st doses)
  • Greenlee: 0.0014 x (total # of 1st doses)
  • La Paz: 0.0049 x (total # of 1st doses)
  • Maricopa: 0.57 x (total # of 1st doses) – # of Pfizer doses allocated to Maricopa
  • Mohave: 0.039 x (total # of 1st doses)
  • Navajo: 0.016 x (total # of 1st doses)
  • Pima: 0.149 x (total # of 1st doses) – # of Pfizer doses allocated to Pima
  • Pinal: 0.072 x (total # of 1st doses)
  • Santa Cruz: 0.011 x (total # of 1st doses)
  • Yavapai: 0.044 x (total # of 1st doses)
  • Yuma: 0.032 x (total # of 1st doses)

These totals serve as initial guidelines, as some adjustments may be made due to Executive Order 2021-01 or if jurisdictions have left doses unordered in previous weeks. These amounts may also be adjusted depending upon doses needed for special projects in a jurisdiction, or state-specific needs. The allocation numbers are then adjusted to ensure minimum orders of vaccine, 975 doses for Pfizer (1,170 doses in upcoming weeks as CDC begins officially counting the sixth dose in every Pfizer vial) and 100 doses for Moderna, are ordered for each county. If a county receives additional doses from a state allocation or for a special project one week, doses may be reduced the next week to ensure they are receiving the appropriate pro-rata allocation overall. The weekly allocations along with the overall allocation totals can be found in our COVID-19 Vaccination Phase by County infographic. This gets updated every Monday.

The first doses and second doses are added together to give an initial county allocation. Again, it is important to note that the initial county allocation is not inclusive of doses allocated through federal programs, such as the CDC Pharmacy Partnership for Long-Term Care and Retail Program, which serve all Arizona jurisdictions.

Federal partners are optimistic that the coming weeks will provide a more consistent and potentially increased vaccine allocation and distribution to state and local partners. While CDC aims to ramp up distribution to retail pharmacies, community health centers, and other federal partners, this will create more opportunities for the public to seek vaccination at locations near them. However, state and local partners must remain cautious that we are not over-extending the number of appointments available at state and local vaccination sites with a potentially shifting vaccine supply.

Arizona continues to demonstrate an ability to rapidly administer vaccinations and increase vaccination capacity and throughout all jurisdictions. Yesterday, we achieved a major milestone of 1 million vaccine doses administered across the state. With additional vaccines and supplies, we can further ramp up vaccination efforts and protect even more Arizonans from COVID-19.