Last reviewed 2026-04-23 · How we verify

Placebo with Thimerosal

Placebo with thimerosal serves as a control formulation containing the preservative thimerosal without active pharmaceutical ingredients.

Placebo with thimerosal serves as a control formulation containing the preservative thimerosal without active pharmaceutical ingredients. Used for Control arm in vaccine safety and immunogenicity trials.

At a glance

Mechanism of action

This is a control arm preparation used in clinical trials, typically to evaluate the safety and tolerability of thimerosal as a vaccine preservative. Thimerosal is an ethylmercury-containing compound historically used to prevent bacterial and fungal contamination in multi-dose vaccine vials. The placebo formulation allows researchers to assess whether observed effects are attributable to thimerosal itself or to other trial components.

Approved indications

• Control arm in vaccine safety and immunogenicity trials

Common side effects

• Local injection site reactions (pain, erythema, swelling)
• Systemic reactions (fever, myalgia, fatigue)

Key clinical trials

• Efficacy/Effectiveness, Safety, and Immunogenicity of LC16m8 Mpox Vaccine in Colombia (PHASE3)
• Efficacy of the Vacucis Candida® Autovaccine (NA)
• A Study in Adults to Test the Effects of Low Dose Thimerosal on Symptoms of COVID-19 (PHASE2)
• A Laboratory Evaluation of the Humoral Immune Response in Adults and Children to the H1 Hemagglutinin (HA) Stalk Domain and Other Influenza A Virus Protein Epitopes, After Administration of GlaxoSmithKline (GSK) Biologicals' Pandemic Influenza Vaccines
• 9-valent CRM 197 Pneumococcal (PHASE2)
• Booster Trial to 07-0019 With A/Anhui/05 With and Without MF59 (PHASE1)
• Immunogenicity, Safety and Tolerability of CSL Limited Inactivated Influenza Vaccine in Adults (PHASE3)

Primary sources

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