A recent report from BBC News outlined in very simple terms some of the procedures involved in vaccine production, which most people are completely unaware of. Very likely, most people have an "out of sight - out of mind" mentality when it comes to vaccines. All they see is a clear liquid in a syringe and they don't want to know what is really in there or how it got there.

Particularly surprising to many people might be the wide use of animal-based ingredients used to mass-produce vaccines. This has caused some problems is the past and continues today. Recently, a "scare" has arisen in Europe when it was discovered that some polio vaccines were made using cells from calf fetuses that were possibly infected with BSE (Mad Cow disease).

This type of scare is not a new phenomenon. Back in the 1950's it was discovered that polio vaccines contained a monkey virus known as Simian Virus 40 (SV40). Millions were given the contaminated vaccines before it was replaced. Now there are reports that SV40 is turning up in human cancers.

Virus Nurseries

One of the main uses of animal cells is as "nurseries" for the modified viruses that constitute the main or "active" ingredient of a vaccine.

The animal cells serve as medium in which the virus in question will replicate and produce more copies of itself.

Scientists have various "cell lines", which are "immortal" cells that can keep on dividing indefinitely. These cells are derived originally from a variety of animal and human sources, including monkeys, hamsters, chicken fetuses or even human fetuses.

Vaccine Soup

However, this is not the only use of animal-derived substances.

The virus-infected cells are bathed in a "soup" made up of ingredients such as glucose for energy, and other chemicals such as growth factors, which can help the cells to develop faster.

Although human growth factors can be extracted, these do not provide as reliable or cost-effective results as other sources, such as fetal calf serum, which is widely used.

Dr Deborah Scopes, a spokesman for the British Society of Immunology, said of the vaccine 'soup': "It's a big broth which helps growth."

Once sufficient numbers of the virus have been replicated, the manufacturers use complex filtration and purification processes to try to remove as much of the substances other than the viruses from the vaccine.

"You don't want to produce an immune response to cow tissue - you want to produce the biggest immune response possible to the viruses, to make the vaccine effective," said Dr. Scopes

BBC News, October 20, 2000