Seasonal Influenza Vaccine Supply for the U.S. 2023-2024 Influenza Season
More of the latest information is available on the total distribution of influenza vaccine doses for the 2023-2024 season.
Flu vaccine is produced by private manufacturers, so supply depends on manufacturers. Vaccine manufacturers have projected that they will supply the United States with 148 million doses of influenza vaccines for the 2024-2025 season. These projections may change as the season progresses. All flu vaccines for the 2024-2025 season will be trivalent (three component). Most will be thimerosal-free, and most will be egg-based.
CDC is not aware of any supply problems with these higher-dose or adjuvanted influenza vaccines as a group; however, influenza vaccine manufacturers are the best source for information on supplies of their influenza vaccines.
For the 2023-2024 season, manufacturers will produce influenza vaccines that do not contain thimerosal and some vaccines that do contain thimerosal. This season, only multidose vial formulations of influenza vaccines will contain thimerosal.
Approximately 91% of projected vaccine supply produced this influenza season will be thimerosal-free or thimerosal-reduced (i.e., preservative-free).
For the 2023-2024 season, 100% of the projected vaccine supply produced will be quadrivalent (four component) vaccines. There will not be any trivalent influenza vaccine available.
Approximately 79% of the projected vaccine supply produced for the 2023-2024 flu season will be produced using egg-based manufacturing technology. The remaining vaccine will be produced using cell-based or recombinant technology.
Information about vaccine supply is available here.
Demand for influenza vaccine varies from year to year. Within each influenza vaccination season, demand varies by month, usually peaking in October or November and rapidly declining after that. Meanwhile, because timing of influenza vaccine production and distribution is unpredictable, availability of the vaccine supply does not always coincide with peak demand. Thus, manufacturers that produce vaccine in middle or late November or later may not be able to sell it all, and patients may be less willing to receive vaccine in this same time frame from providers who have vaccine available, even though late season vaccination is encouraged and mostly beneficial.
Influenza vaccine pre-booking typically occurs between January and March. Some formulations of vaccine may still be available for purchase. Providers should contact distributors and local vendors about remaining supply. In addition, beginning in early October each year, information about manufacturers and distributors who still have influenza vaccine available for sale can be found at https://www.izsummitpartners.org/ivats/.
Updates on the distribution of influenza vaccine doses for the 2023-2024 season will be provided as the season progresses.
Influenza vaccine distribution has begun for the 2023-2024 influenza season. People should consult CDC’s guidance on the best timing for getting their vaccine.
Currently, influenza vaccine manufacturers are not reporting any expected delays in national influenza vaccine supply or distribution this season.
Influenza vaccine production and distribution in the U.S. are primarily private sector endeavors. CDC encourages manufacturers and distributors to use a distribution strategy in which providers receive smaller shipments to allow as many providers as possible to begin vaccination activities early in the vaccination season. Ideally, the intervals between shipments are short so that each provider has a continuous supply and can continue vaccinating patients without interruption. To make sure your provider has influenza vaccine available, call ahead to confirm availability. There also may be other locations in your area that have vaccine available.
CDC will continue to provide weekly updates on total influenza vaccine doses distributed throughout the influenza season.
Influenza vaccine production and distribution in the United States are primarily controlled by the private sector. CDC does not have the authority, or relationships with providers necessary to carry out or control vaccine distribution.
CDC encourages influenza vaccine manufacturers and distributors to use a distribution strategy that provides vaccine to all provider types in a comparable timeframe. Such an approach allows the broadest possible access for vaccine throughout the season and is consistent with national data that indicate adults in the U.S. receive influenza vaccine in a wide variety of venues, including private provider offices, worksites, clinics, hospitals, health departments, retail settings, and senior centers. While there is a relationship between age or health status and the location in which vaccines are received, the data demonstrate that all of these venues serve at least some older adults or higher risk patients.
The timing of influenza vaccine production varies from year to year and depends on multiple factors, including the viruses chosen for inclusion in the vaccine. Even in a year in which each step of production goes well, it isn’t possible for all of the doses to be produced and distributed before the beginning of the vaccination season because influenza vaccine manufacturers already produce vaccine at or near full capacity.
Manufacturers say that because of the unpredictable nature and complexity of biologics production, they cannot always anticipate when vaccine lots will be completed and released. Distributors must rely on the manufacturers to provide them with this information. Both manufacturers and distributors are reluctant to project very far into the future about when shipments will be made because they do not want to create unrealistic expectations among customers.
The primary reason for the variation in timing is because different types of vaccine providers receive their vaccine from different sources. A provider may order influenza vaccine (1) directly from the manufacturer; (2) from a distributor, who is a customer of the manufacturer; or (3) from a secondary distributor, from whom the provider also receives other medical products. Some of these routes of distribution are more direct than others, which can affect the timing of vaccine delivery.
Influenza vaccine production begins as early as 6 to 9 months before the beginning of vaccine distribution. Even with this early start, it isn’t possible to complete the entire production and distribution process prior to flu season, in part because of the limited number of influenza vaccine manufacturing plants in the United States and the large number of doses that are produced each year. Instead, influenza vaccine distribution takes place in a phased fashion over a number of months. Distribution usually begins in late summer and is complete near the end of November or early in December. This may result in some uncertainty that makes it difficult for vaccine providers to plan their vaccination activities. Manufacturers and distributors try to get some vaccine to as many providers as possible as early as possible so that they can begin vaccinating their patients.
Influenza vaccine production and distribution are primarily controlled by the private sector. The Department of Health and Human Services and CDC do not have the authority to control influenza vaccine distribution, to manage such an effort. However, the Department has made significant efforts to enhance production capacity of seasonal influenza vaccines, including supporting manufacturers as they invest in processes to stabilize and increase their production capacity.
The challenges associated with the U.S. influenza vaccine supply are multi-faceted. Influenza viruses change from year to year, so influenza vaccines must be updated annually to include the viruses that will most likely circulate in the upcoming season. Once the viruses are selected for the new formulation, manufacturers operate under a very tight timeline for producing, testing, releasing and distributing the vaccine. Due to these time constraints, any problems encountered during production may cause shortages or delays. Such problems have impacted the influenza vaccine supply in some prior influenza seasons.
Beginning in 2004, CDC began purchasing a late-season influenza vaccine stockpile to provide a limited quantity of vaccine for children (using Vaccines for Children [VFC] Program funds) to address urgent supply problems that may exist in December, January or beyond. In most years, influenza disease activity does not peak until January or later, so this approach of stockpiling can be quite useful if vaccine production delays or shortages drive demand later into the influenza vaccination season.