MMR vaccine

Epidemiology

Studies have shown that vaccination markedly reduces the mortality rate due to measles (CDC report on effect of vaccination against measles in Africa between 1996-2002).

Mumps is another viral disease of childhood that used to be very common. A known but relatively rare complication of mumps is causing sterility in males.

Rubella, otherwise known as German measles was also very common before the advent of widespread immunization against it. The major risk in rubella is if a pregnant woman is infected, her baby may contract congenital rubella which can cause significant congenital defects.

All three diseases are highly contagious.

The MMR vaccine was designed to be a single shot vaccine that protects against all three viral diseases. Significant improvements in reducing the incidence and therefore, the complications of the three diseases above has been attributed to widespread population vaccination with MMR.

Whilst there are known but rare side effects from using the MMR vaccine, in the public health perspective, the overall benefit to the population is vastly in favour of continued vaccination.

The MMR controversy

Controversy has arisen because some scientists and parents claim that the vaccine may be linked to the development of a number of conditions, such as autism, bowel disorders such as Crohn's disease, and the brain disorder Creutzfeldt-Jakob disease (CJD).

During the 1980s and 1990s, a number of lawsuits were brought in the United States against manufacturers of vaccines, alleging that the vaccines had caused a variety of physical and mental disorders in children. While these were inconclusive, they did lead to a massive jump in the costs of the MMR vaccine as pharmaceutical companies sought to cover potential liabilities. By 1993, Merck had become the only company willing to sell MMR vaccines in the United States and the United Kingdom. Two other MMR vaccines were withdrawn in the UK in 1992 on safety grounds.

In September 1995, the Legal Aid Board in the UK granted a number of families financial assistance to pursue legal claims against the state health authorities and the vaccine's manufacturers, claiming that their children were killed or seriously injured by the MMR vaccine. A pressure group called JABS (Justice, Awareness, Basic Support) was established to represent 800 families with children who were "vaccine-damaged."

In 1996, a controversy broke out in New Zealand concerning an allegation that the MMR vaccine could spread CJD. A Melbourne University academic claimed that MMR contained a human blood product, serum albumin, and could therefore spread CJD. The controversy died down after doctors highlighted the fact that serum albumin is not an ingredient of the MMR vaccine.

Dr. Andrew Wakefield's report

In February 1998, a group led by Dr. Andrew Wakefield published a report on the matter in the respected journal The Lancet. The report analysed the cases of twelve autistic children, admitted to the Royal Free Hospital in north London in 1996-1997. It suggested that there was an "association" between the children's autism and their inoculation with the MMR vaccine. Eight of the twelve children studied were said to have blamed the MMR vaccine, saying that symptoms of autism had set in within days of vaccination at approximately 14 months. The report did not present any scientific evidence to corroborate the association or the mechanism by which the vaccine was apparently resulting in autism. At a subsequent press conference, however, Dr. Wakefield strongly criticised the MMR vaccine and declared that "I can't support the continued use of these three vaccines given in combination until this issue has been resolved."

The press conference sparked a major health scare and lurid headlines in the United Kingdom. Rebuttals by UK Government and National Health Service (NHS) doctors and scientists were disbelieved by many parents, not least because previous government pronouncements on safety had been widely discredited in the 'Mad Cow' (BSE) affair. It was also alleged that the government was unwilling to support the use of separate vaccines because the NHS could not afford them. As a result, the takeup of MMR dropped sharply, from 92% in 1996 to 84% in 2002. In some parts of London, it was said to be as low as 60% - far below the rate needed to avert epidemics of measles. Although an epidemic has not yet occurred, measles rates have increased and doctors have warned of the high likelihood of a future epidemic because of the failure of the protection offered by herd immunity.

A major factor in the controversy is that only the combined vaccine is available on the UK National Health Service; those who do not wish to have it given to their children must either have the separate vaccines given privately, or not vaccinate their children at all. The Prime Minister, Tony Blair, has refused to state whether his son Leo has received the MMR vaccine but has strongly supported the vaccine in public. The great majority of doctors prefer to administer the combined vaccine rather than the separate ones, as it is less distressing to the child and people are less likely to go through three vaccinations than one single one.

Following the publication of Wakefield's report, many studies - often more more extensive and detailed than that initially done by Dr. Wakefield's team - were conducted by other scientists and doctors to corroborate his findings. No corroboration was found, and all concluded that the MMR vaccine was in fact safe. Dr. Wakefield did not accept these results and left his job at the Royal Free Hospital in 2001. He now campaigns against the MMR vaccine on more or less a full time basis, travelling to the United States and Europe to lecture on the vaccine's alleged dangers.

In February 2004, it emerged that at the time that Dr. Wakefield had published his report, he was being paid £5555 000 to assist lawyers seeking scientific evidence of a link between autism and the MMR vaccine. According to a Sunday Times investigation, several of the parents quoted as saying that MMR had damaged their children were also litigants. This was not revealed to either The Lancet or Dr. Wakefield's co-researchers. On February 20, The Lancet said that it should have never published Dr. Wakefield's study, which was "flawed" because Dr Wakefield had "a fatal conflict of interest." Several of Dr. Wakefield's co-researchers also strongly criticised the lack of disclosure. The General Medical Council, which is responsible for supervising medical ethics in the UK, has said that it is to investigate the affair. The investigation is likely to focus on whether Dr. Wakefield breached guidelines on the conduct of research, which include rules regarding potential conflicts of interest.

The investigation which led to the authors retraction was carried out by Brian Deer for The Sunday Times of London. http://briandeer.com/mmr-lancet.htm

External links

• UK National Health Service information on the vaccine
• The anti-vaccination view on MMR

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