Facts My Doctor Told Me About Preservative-Free Vaccines

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Vaccines are products that protect people against serious and deadly diseases. Unlike medicines that treat or cure diseases, vaccines prevent them. 

Recently I visited our paediatrician to discuss my kids’ vaccination. While conversing, I asked him about the use of preservatives in vaccines. I read a few articles online about this and ever since I had multiple queries in my mind. The doctor was kind enough to spare a few minutes and address all my queries in detail. He shared some very pertinent and informative facts about preservative-free vaccines, which I think all parents should know. 

Why are preservatives added to vaccines? 

Preservatives are compounds that prevent the growth of germs or microorganisms, such as bacteria or fungi. They are used in vaccines to prevent fungal or bacterial growth (especially if the vaccine is accidentally contaminated). 

Thimerosal is a mercury-based preservative that has been used for decades in medicines and vaccines. Vaccines are commonly packaged in multi-dose vials. In some cases, preservatives including thimerosal, are added during the manufacturing process to prevent germ growth. Thimerosal does not stay in the body for a long time, so it does not build up and reach harmful levels. It is considered to be a safe product when used in low doses in vaccines.

However, with increasing changes in manufacturing technology, the need to add preservatives during the manufacturing process has remarkably decreased.

Preservative-free Vaccines

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Important Facts About Preservative-free Vaccines 

Here are some facts that my doctor shared about preservative-free vaccinations – 

  1. The preservative-free vaccines are those vaccines that do not contain any preservative like thimerosal.
  2. These vaccines come in a single dose vial, unlike many that are offered in multi-dose vials (i.e vials containing multiple doses of vaccines). 
  3. Preservative-free vaccines are also delivered at the same time and the same dose as the traditional vaccines.
  4. In the past, prior to the initiative to reduce thimerosal from vaccines, the maximum cumulative exposure to mercury via routine childhood vaccinations during the first six months of life was 187.5 microorganisms. With the introduction of thimerosal- preservative-free formulations of DTaP, Hib and Hepatitis B, the maximum cumulative exposure from these vaccines decreased to less than 3 microorganisms of mercury in the first 6 months of life. This level is well below the EPA calculated guideline
  5. As per studies, there is no evidence of harm caused by the low doses of thimerosal in vaccines, except for minor reactions like redness or swelling at the injection site. Still, in July 1999, the Public Health Service agencies, the Institute Of Medicine, the American Academy of Pediatrics, and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure (to decrease the overall exposure to mercury in young infants). 3
  6. Now, all new vaccines licensed since 1999 are free of thimerosal as a preservative.
  7. Currently, all hepatitis vaccines manufactured contain either no thimerosal or only trace amounts. 
  8. FDA has approved thimerosal/preservative-free formulations (containing either no or only trace amounts of thimerosal) for the inactivated influenza vaccines manufactured by Sanofi Pasteur. 
  9. Vaccines that do not contain thimerosal as a preservative are also available for adolescents and adults.
  10. The use of preservatives in vaccines has led to many doubts and controversies about their safety and efficacy. Many doctors have linked these to neurodevelopment disorders, speech and language delay, etc in kids. As such there are no proven studies or scientific evidences found in this regard. Still the removal of preservatives from vaccines has reduced all sorts of risks and fears people had related to vaccinations. 

Parents want to do everything possible to make sure their children are healthy and protected from preventable diseases. Vaccination is the best way to do. All vaccines undergo long and careful review by scientists, doctors and the federal government to make sure they are safe. Most childhood vaccines are 90% to 99% effective in preventing diseases. And if a vaccinated child does get the disease, the symptoms are usually mild than in a child who hasn’t been vaccinated.

As parents we should ensure that our children are vaccinated on time and maintain a vaccination record. Medical advice and supervision are also important during vaccination of kids.

So if you are new parent and have any queries related to vaccines or use of preservatives in vaccines, I would suggest you speak to your health care expert (like I did) and gain all the knowledge possible. This will help you make an informed choice in this regard. 

What’s #YourCareQuotient? How much do you understand your child when it comes to sleep patterns, feeding and vaccination? Take the easy, interactive quiz that guides you and get the childcare guide now. 


  1. https://www.fda.gov/vaccines-blood-biologics/vaccines/thimerosal-vaccines-questions-and-answers
  2. https://vaccineindia.org/article/thiomersal
  3. https://www.cdc.gov/vaccinesafety/concerns/thimerosal/index.html
  4. https://www.who.int/immunization/newsroom/thiomersal_information_sheet/en/

Image Courtesy : Shutterstock.com

Disclaimer: This post is in collaboration with Sanofi Pasteur. However, the views and opinions expressed in this post are of the author’s alone.


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