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The MMR vaccine is a combined vaccine for immunization against measles, mumps and rubella. It is generally administered to
children around the age of 1 year, with a booster dose before starting school (i.e. age 4/5). It is widely used around the world;
since its introduction in the 1970s, over 500 million doses have been used in over 60
countries. Those receiving the vaccine may experience a number of side-effects: a rash or slight fever for a few days, one to two
weeks after receiving the vaccine, occasionally accompanied by a mild swelling of the salivary glands and some aching or swelling
of the joints. These effects are mild and temporary, vanishing within a few days. Children rarely have more serious reactions -
only about one in every 100,000 vaccinations results in a severe allergic reaction. If treated quickly, the child should fully
recover.
Epidemiology
Before the widespread use a vaccine against measles, the incidence of measles was so high that in 2004, any patient over the age of 55 is assumed to have had had measles in the past. Today, because
of vaccination, the incidence of measles in countries with routine childhood vaccination has fallen to less than 1% of people
under the age of 30. Measles has a significant complication rate which includes pneumonitis and encephalitis.
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 £55 000 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
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