In General - A vaccine works by giving a mild dose of the illness - and thus stimulating the recipient's immune system to give immunity to the disease. The virus used can be killed or living. In the latter case it must be weakened "attenuated" otherwise it would cause the disease. The weaker it is made, the less it causes side effects - and the less immunity it will give. Side effects are thus balanced against immunity. Nearly all vaccines thus have to be so weak that they will only give temporary immunity.

Measles Vaccine.

The first "Edmonston" vaccine was based on a killed measles virus. It was used between 1963-67. "It was abandoned when analysis indicated that it provided only short-term immunity and .. vaccinated children developed severe reactions called "atypical measles".

Next the measles virus was not killed but "attenuated' or weakened by being transplanted into various tissue cultures and eventually by being grown in chicken embryos. This vaccine was known as the Edmonston B. But 'one third of all recipients developed high fever, and half got a rash.

The next varieties of vaccine were developed from this by weakening it. The Enders strain was developed by weakening the virus by transplanting it 40 times through cold chicken embryos. The Schwarz strain was developed by transplanting (passaging it) 85 times through chicken embryos. The Enders is the current measles vaccine used in the United States and is manufactured by "Merck, Sharpe and Dohme". The Schwarz is used elsewhere in the world including in the UK.

There have also been other measles vaccines developed - including one that was grown in the kidneys of killed monkeys.p172 (WHO warns that such vaccines carry a risk of carrying monkey viruses.) Reactions of severe hypersensitivity were put down to an unknown contaminant in a particular vaccine lot that was distributed in Norway. It is not said whether this was a foreign virus.

Encephalopathy and Encephalisitis. (Acquired adnormality of, injury tor impairment to the functions of the brain) This can happen as a rare consequence of natural measles. The first case of it following measles vaccination appeared in 1987 (ref p123) There were 47 cases reported in the UK linked to vaccination 1968-74 during a time when 3 million doses were distributed. (It should be noted that UK government studies indicate less than one in five cases are reported as vaccine related - the under-reporting is due to the general medical presumption that the vaccines cannot be the cause of illnesses.)

P127 A study based on a new passive surveillance system in Canada reported a rate of 1.1 cases of meningitis or encephalitis per 100,000 doses of MMR.

Mumps Vaccine

Mumps is naturallyrare in the first year of life - probably due to maternal antibodies.

The first 1946 mumps vaccine was based on killed mumps virus - but it only protected 4 out of 5 recipients - and only for about one year.

Thus a stronger vaccine was developed based on living mumps virus. The Jeryl Lynn strain now used in the US weakens the mumps virus by passing it (transplanting it) many times through hens' eggs and chicken embryos. In Russia they similarly developed the Leningrad-3-Parkov strain and in Japan they developed similarly the Urabe AM9 strain.