How Are Vaccines Made?

Bacterial vaccines are grown in a culture medium which provides the required nutrients. Viruses for vaccines are grown in living tissue or using continuous cell-lines. Animal blood products and tissues as well as human tissue cell-lines are used in this process. For example:

  • tetanus bacteria for vaccines is cultured in bovine (calf) serum
  • viruses for polio vaccines are grown in African green monkey kidney (VERO) cells
  • rubella, rotavirus and chickenpox viruses are cultured on human diploid cells (foetal cells).
  • measles, mumps, influenza and Q fever vaccine strain viruses are grown in chick embryo cell cultures.
  • hepatitis B and HPV vaccines are produced using genetically modified yeast cells.

Foreign proteins, bacteria and viruses from these cultures and tissues can contaminate the vaccines and may trigger severe allergic reactions.35

  • In 2004 the US Federal Drug Administration (FDA) announced plans to minimise the risk of mad-cow infected components ending up in childhood vaccines and other products.36
  • Japanese encephalitis vaccine was withdrawn for teenagers in Japan following reports of encephalitis, attributed to contamination with mouse brain proteins in the vaccine.37

Vaccines can vary in the amount of ‘bacterial toxoid’ or ‘attenuated (weakened) viruses’ from one batch to another. Some lots of vaccines can cause more side effects than others and are called ‘hot lots’.

  • Vietnam suspended Hepatitis B vaccine after 3 newborn babies died suddenly after being administered vaccine related to 2 batches.38

35 Immunisation Myths and Realities, 3rd Edition, Commonwealth of Australia, April 2001, p.17
36 Henderson, Diedtra, Miami Herald, 22/9/2004
37 Japan Calls a Halt to Japanese Encephalitis Vaccinations, Xinhua News Agency, 30/5/2005
38 WHO to Investigate Hepatitis Vaccine Deaths in Vietnam, 10/6/2007,

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