What is thimerosal, the flu vaccine ingredient targeted by RFK Jr.?

[womanofthehills]

60. It was removed yrs ago from childhood vaccines

However- it’s still in 9% of flu vaccines. It’s only in multi dose flu vaccines to kill bacteria as the vial contains many doses the pharmacist dips into. It’s not in single vial flu vaccines - one vial per person.


Kennedy wants to end multi dose flu vaccines - only have single vial.

The pharmacist must also shake the multidose vaccines vigorously.

Groc

Yes, pharmacies and healthcare providers are required to shake multi-dose flu vaccine vials thoroughly before withdrawing each dose to ensure the ingredients, including the preservative thimerosal (which contains ethylmercury), are evenly distributed. This is a standard safety practice to prevent uneven dosing and ensure each dose contains the correct amount of vaccine and preservative.

According to guidelines from the CDC and package inserts for multi-dose flu vaccines like Fluzone Quadrivalent and Afluria Quadrivalent, shaking the vial is necessary because the vaccine is a suspension that may settle, and thorough mixing ensures a homogeneous mixture. For example, the Fluzone Quadrivalent package insert specifies to "shake the prefilled syringe or multi-dose vial" before administration to ensure uniformity. Similarly, Afluria Quadrivalent instructions state to "shake the vial thoroughly before withdrawing each dose" to resuspend the contents.

This step is critical because uneven distribution could lead to inconsistent amounts of the active ingredients or thimerosal in each dose, potentially affecting efficacy or safety. Pharmacies follow these protocols to comply with manufacturer instructions and CDC guidelines for safe vaccine administration.[](https://www.drugs.com/pro/afluria-quadrivalent.html)[](https://www.drugs.com/pro/fluzone-quadrivalent.html)