Are multi-dose vials of hepatitis vaccines still used in 2025 and do they contain preservatives like thimerosal?
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Executive summary
Yes — multi-dose vials and thimerosal remain part of the vaccine landscape in 2025, but their use has been sharply narrowed: thimerosal has been removed from most childhood vaccines since the late 1990s and is now primarily associated with some multi-dose influenza and other older formulations; hepatitis B vaccines on the U.S. market are available in preservative‑free, single‑dose presentations and thimerosal‑containing hepatitis B products were largely removed beginning in 1999 [1] [2] [3].
1. What “multi‑dose vial” and “thimerosal” mean in practice
A multi‑dose vial is any vaccine container designed to deliver more than one dose and, historically, manufacturers added antimicrobial preservatives such as thimerosal (an ethylmercury compound) to prevent bacterial or fungal growth after repeated needle entries; U.S. public health documents and regulators describe that role directly [1] [4]. The FDA and CDC state thimerosal is about 50% mercury by weight and has decades of use as a vaccine preservative to ensure safety when vials are used for multiple injections [4] [1].
2. Are multi‑dose vials still used in 2025?
Yes — regulators and advisories continue to discuss mult-dose vials as relevant to immunization programs. The FDA explains that thimerosal-supported multi‑dose packaging has facilitated large influenza campaigns and other programs globally [4]. CDC presentations in 2024–2025 explicitly list thimerosal‑containing vaccines and note the share of influenza vaccines distributed in 2024–25, indicating multi‑dose formats remain in circulation for some products [3] [4].
3. Do hepatitis B vaccines still contain thimerosal?
Available evidence in the provided reporting shows hepatitis B vaccines sold in the U.S. are offered in preservative‑free, single‑dose formulations and that thimerosal‑containing hepatitis B products were removed from the market beginning in 1999; multiple CDC and review documents note the phase‑out of thimerosal from hepatitis B vaccines [2] [5] [6]. Product labeling also documents preservative‑free pediatric/adolescent formulations for licensed hepatitis B vaccines such as RECOMBIVAX HB [7].
4. Why was thimerosal phased out of many childhood vaccines?
Federal health agencies, pediatric authorities and manufacturers agreed in 1999 to reduce or eliminate thimerosal from pediatric vaccines as a precautionary measure because it contains a form of mercury; that policy change led manufacturers to introduce preservative‑free single‑dose hepatitis B and other pediatric vaccines [1] [5]. The CDC and other reviewers emphasize the action was precautionary despite a long record of safety studies and no convincing evidence linking vaccine thimerosal at the doses used to neurodevelopmental disorders [3] [8].
5. Where thimerosal still appears and why that matters
Regulators and the FDA point out thimerosal is still used in some vaccines where multi‑dose packaging is operationally important — for example, many seasonal and pandemic influenza multi‑dose vials — because the antimicrobial preservative allows safe use of a vial across many patients during mass campaigns [4] [3]. CDC slide decks and FDA pages in 2024–2025 highlight that most non‑influenza childhood vaccines never contained thimerosal and that during 2024–25 the large majority of influenza vaccine supply was either thimerosal‑free or in single‑dose formats, though multi‑dose vials with preservative remain in use [3] [4].
6. Safety debate and political context in 2025
Scientific bodies continue to report no convincing link between low‑dose thimerosal in vaccines and autism or neurodevelopmental harm, and CDC reviews through 2025 summarize epidemiologic research on thimerosal exposure from hepatitis B vaccines [9] [3]. At the same time, vaccine policy debates in 2025 — including ACIP deliberations and changes to hepatitis B birth‑dose recommendations — have elevated thimerosal as an item of public concern and political focus, with some advisory votes endorsing thimerosal‑free options and opponents arguing the precautionary path has unintended public‑health consequences [3] [10] [11] [12].
7. Practical takeaway for clinicians and parents
If the question is specifically about hepatitis B shots today, public health documents and product labels indicate that licensed single‑antigen hepatitis B vaccines used in newborns and infants in the U.S. are available preservative‑free and that thimerosal‑containing hepatitis B products were removed beginning in 1999 [2] [7]. For other vaccines — notably influenza — multi‑dose vials containing thimerosal or other preservatives still exist and are used in some settings for logistical reasons [4] [3].
Limitations and sourcing note: This analysis uses CDC, FDA, manufacturer and peer‑reviewed material and contemporary reporting supplied above; available sources do not mention every brand‑level vial configuration in every country in 2025, and specific product offerings can vary by manufacturer and jurisdiction [4] [7].