I'm pregnant and also a scientist, so I understand the importance and benefit to risk ratio of annual flu shots. However, as a first time new mom, I'm a bit more hesitant this year about getting a flu shot while pregnant. Are there any good studies examining the effects of a non-thimerosal/non-mercury containing flu shot on the children of women who got the shot when they were pregnant? Furthermore, what exactly is the adjuvant/diluent in a non-thimerosal/non-mercury containing flu shot? Thanks for your assistance, D

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Hi dmjonesdavis and thank you for your question. Here's an answer from John Treanor, M.D., chief of the Infectious Diseases Division, University of Rochester Medical Center:

 

There are currently two inactivated flu vaccines available in the U.S. that are completely thimerosal free – Fluzone (Sanofi Pasteur) in single dose prefilled syringes, and Afluria (CSL) in single dose prefilled syringes. Prefilled vaccine from Novartis (Fluvirin) and GSK (Fluarix) also contain minimal amounts of thimerosal. I am not aware of studies that examine the relative effectiveness of flu vaccines that do or do not contain thimerosal but I would expect them to be equivalent. Inactivated vaccines are generally suspended in some form of sterile physiologic saline, which can be found in the package insert. For example, Fluzone is suspended in sodium phosphate-buffered isotonic sodium chloride solution. From the package insert "Gelatin 0.05% is added as a stabilizer. Each 0.5 mL dose may contain residual amounts of formaldehyde (not more than 100 µg), polyethylene glycol p-isooctylphenyl ether (not more than 0.02%), and sucrose (not more than 2.0%)." To my knowledge, none of these agents is felt to be responsible for adverse effects at the minimal amounts contained in a dose of vaccine. None of the influenza vaccines currently licensed in the United States contain an adjuvant.

 

NOTE: Top medical experts on the cold and flu answer questions like these on the OnCall+ Cold & Flu: http://abcnews.go.com/health/coldandflu.

 

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