Which 2025 influenza vaccines are thimerosal-free or available in single-dose vials?
Executive summary
The federal advisory committee (ACIP) voted in June 2025 that children ≤18, pregnant people and adults should receive only single‑dose influenza vaccines that do not contain thimerosal; CDC and HHS subsequently adopted guidance aligning supply and programs with that preference (ACIP vote and CDC recommendation) [1][2]. Manufacturers projected up to 154 million doses for 2025–26, and most of that supply is expected to be thimerosal‑free because multi‑dose, thimerosal‑containing vials already made up only a small share of U.S. influenza shots (projected supply and prior percent thimerosal‑containing) [2][3].
1. What the new guidance actually says and who issued it
In June 2025 ACIP voted that children aged ≤18 years, pregnant women and all adults should receive seasonal influenza vaccines only in single‑dose formulations that are free of thimerosal as a preservative; CDC repeated that recommendation for the 2025–26 season, and HHS later adopted ACIP’s recommendation into policy statements [1][2][4].
2. Which formulations are in practice thimerosal‑free
Single‑dose presentations — prefilled syringes and single‑dose vials — are routinely manufactured without thimerosal; product labels and CDC materials show that many licensed influenza products are available as preservative‑free single‑dose prefilled syringes (for example, Flucelvax prefilled syringes contain no preservative) [5][6]. CDC and manufacturer projections indicate most of the 154 million projected doses for 2025–26 will be thimerosal‑free [2][7].
3. How common thimerosal‑containing multi‑dose vials were before the change
Before the 2025 policy push, multi‑dose vials with thimerosal accounted for only a small share of U.S. influenza vaccinations — analyses put thimerosal‑containing doses at roughly 4% of administered influenza vaccines in 2024–25, with over 95% being thimerosal‑free [3][8]. Public health trackers and state program memos note that multi‑dose vials historically made up a minority of supply [9][10].
4. Practical availability: which products and settings
Product labeling and clinical summaries list both single‑dose and multi‑dose presentations for many brands; for 2025–26 manufacturers provided single‑dose prefilled syringes for major vaccines (Flucelvax 0.5 mL prefilled syringes contain no preservative) while corresponding multi‑dose vials, when offered, include thimerosal [5][6]. Several state and program notices (VFC, public health memos) explicitly limited public program orders to single‑dose formulations this season, restricting access to multi‑dose vials through those channels [11][10].
5. Safety context and competing perspectives
Major public‑health agencies long ago removed thimerosal from most childhood vaccines as a precaution; however, leading health authorities (CDC, FDA, WHO) have said evidence does not show harm from the tiny thimerosal amounts previously used in vaccines. Reporting and medical societies note the ACIP vote was controversial because some committee members and public health experts argue there is no evidence of harm and that multi‑dose vials have programmatic benefits such as lower cost and easier mass campaign logistics [12][13][14].
6. Policy and political context that shaped the change
HHS’s press materials frame the move as implementing ACIP recommendations and restoring public trust; coverage from news outlets and medical journals highlights that the ACIP vote and HHS adoption occurred amid scrutiny about the committee’s new membership and advocacy histories, creating debate over whether the action was driven by safety evidence or political/ public‑confidence considerations [4][12][13].
7. Limitations of current reporting and what’s not in these sources
Available sources document the ACIP vote, CDC guidance, manufacturer projections and the small historical share of thimerosal‑containing doses [1][2][3]. Available sources do not mention comprehensive product‑by‑product 2025 inventory lists linking every licensed brand and all lot‑level presentations to thimerosal content; they also do not provide exhaustive regional clinic‑level availability data for single‑dose vials versus multi‑dose vials (not found in current reporting).
8. What this means for someone getting a flu shot in 2025–26
Patients seeking thimerosal‑free influenza vaccine can expect single‑dose prefilled syringes or single‑use vials to be the default in most settings because ACIP/CDC recommendations and program policies favor those presentations and manufacturers projected most doses will be thimerosal‑free; multi‑dose thimerosal‑containing vials remain rare and are being de‑emphasized in public programs [2][7][11].
Sources cited: CDC ACIP guidance and season page [1][2], HHS adoption statement [4], coverage of the vote and context [12][13], supply and prevalence data [3][7], product labeling/examples [5][6], state/program memos [11][10].