MMR
Friday, 21, Nov 2008 03:05
What is MMR?
MMR is a combined vaccine for the three potentially highly harmful childhood diseases measles, mumps, and rubella (also known as German measles).
It is given to children on the NHS in two doses: the first between the ages of 12 and 15 months and a second 'booster' dose, typically before a child goes to school between the ages of three and five years. All EU member states, the USA, Canada, Australia and New Zealand recommend a two dose strategy.
Like all vaccines, the MMR vaccine works by exposing the child to a controlled amount of the three viruses, which have been medically 'attenuated' to prevent their escalation.
Exposure to the viruses triggers the production of antibodies, which neutralise their effect. The child's immune system then 'records' details of the virus, enabling it to more effectively fight off the naturally occurring viruses in the future.
In recent years, public confidence in the MMR triple vaccine has been shaken by a series of medical studies and anecdotal evidence linking it to a number of serious medical conditions.
Background
MMR replaced the use of single vaccines for the three diseases in the UK in 1988. Governments since then have argued that the triple vaccine more effectively protects children, as the single vaccines require six separate inoculations - increasing the risk that the full course is not completed.
Since its introduction, the MMR vaccine has been linked with diseases such as asthma, autism, Guillain Barre Syndrome, inflammatory bowel disease, mumps virus meningitis and subacute sclerosing panencephalitis.
The Government and medical authorities dismiss these links, but the parents of many autistic children believe that MMR triggered their child's condition and public concern remains strong - evidenced in the decline in vaccination coverage from 92 per cent in 1995 to less than 80 per cent in 2003 (a figure closer to 60 per cent in some parts of London). This decline followed the 1998 claims of the Inflammatory Bowel Disease (IBD) Study Group at the Royal Free Hospital (RFH), led by Andrew Wakefield, which suggested the possibility of a link between MMR, IBD and autism.
The 1998 study was published in 'The Lancet', arguing there was evidence to suggest a 'new syndrome' involving MMR, autism and bowel disorders arising in some children shortly after receiving the MMR vaccine. However, Dr Wakefield has since been accused of research misconduct, such as not disclosing payments he received from the Legal Aid Board, and The Lancet stated in February 2004 that this "information would have been material to our decision-making about the paper's suitability, credibility, and validity for publication".
In April 2000, another study by Dr Wakefield and Professor John O'Leary, Director of Pathology at Coombe Women's Hospital in Dublin, presented evidence to the US Congress, claiming to show the measles virus in the guts of 24 out of 25 autistic children they had examined. In January 2001, Dr Wakefield alleged in an article in the journal 'Adverse Drug Reactions and Toxicology Review' that MMR had not undergone full safety assessments prior to licensing, and in February 2002, he and Professor O'Leary published another paper alleging a link in 'Molecular Pathology'.
The media has played a significant role in raising public concern about MMR, some have said whipping up public hysteria, to the point where it is a major public health issue in its own right.
Controversies
Numerous British and international studies, in both the public and private sector, have refuted the alleged link between MMR, IBD and autism - and yet the public perception that MMR is unsafe persists.
Inoculation rates fell below 90 per cent in the late 1990s, creating a pressing public health problem, as the prevention of epidemics demands a very high rate of vaccination.
The Government frequently points to the decision in the 1970s to allow parents to opt out of the pertussis (whooping cough) vaccination following fears that it was causing brain damage: coverage fell from 80 per cent to 30 per cent, and three major epidemics followed, in which at least 100 children died.
The only major industrialised country that does not recommend MMR is Japan, which withdrew the vaccine in 1993. The strain of mumps used in its MMR combination (Urabe) was found to have caused some cases of mumps virus meningitis. The Urabe strain is not used in the UK's MMR supply.
It has also been suggested that the combination of the three viruses in two doses is too great an attack for children's immune systems to cope with - resulting in side-effects and complications. The Government and NHS deny that there is any medical support for this claim.
Nonetheless, many parents' concerns have led them to seek single vaccines in preference to MMR. This raises problems, because no single vaccines for any of the three diseases are licensed for use on children in the UK. However, doctors and companies are able to import them under certain circumstances, causing considerable anger within the medical community.
In early 2002, it came to light that some children in Haringey were being removed from GPs' lists because of their parents' refusal to accept the MMR vaccine. This, along with popular concerns about MMR and the medical community's insistence that there is nothing to worry about, have done little to improve public opinion about the vaccine. Some people have said that the refusal of Government Ministers, including former Prime Minister Tony Blair, to confirm or deny whether their children received the MMR vaccine has increased public alarm.
In February 2004, it emerged that Dr Wakefield had not disclosed payments of £55,000 he had received from the Legal Aid Board, prior to the publication of the 1998 Lancet study, to determine whether there was evidence to support action by parents claiming that MMR had harmed their children. In June 2007 the GMC began an inquiry into allegations of serious professional misconduct by Dr Wakefield and two of his colleagues.
In August 2008, the Chief Medical Officer, concerned about a possible measles epidemic, wrote to all Primary Care Trusts asking them to offer the MMR vaccine to every child up to the age of 18 who had not been vaccinated and to urge parents to have their children immunised. The Department of Health announced that it would make extra vaccine and funds available to help local health trusts with a vaccination campaign.
Statistics
It is estimated that around three million children aged 18 months to 18 years have missed either their first or second MMR vaccination.
The previous success of the MMR vaccination programme reduced the number of measles cases to very low levels for a number of years. Between 1992 and 2006 there were no deaths from acute measles in England. However there was one death in 2006 and another in 2008.
The number of cases of measles in England is rising following a decade of relatively low vaccine uptake. In 2006 and 2007 there were 1,726 confirmed cases in England and Wales - more than the previous 10 years put together. From 1996 to 2005 there was a total of 1,621 confirmed cases.
An average PCT will receive additional funding of £30,000 to help with the MMR vaccination campaign.
Source: Department of Health – August 2008
Analysis of laboratory confirmed cases of measles estimated that one dose of MMR vaccine provides over 95% protection against measles, whereas two doses provide almost 100% protection.
In January to March 2008, uptake of the MMR vaccine in the UK reached 84% uptake for the first dose but was only 76% for the second dose.
Source: Health Protection Agency – September 2008
Quotes
"If we continue to accumulate unvaccinated children, measles will spread among them - at some point there will be a measles epidemic………The evidence on MMR is absolutely clear - there is no link between the vaccine and autism."
Professor David Salisbury, director of immunisation at the Department of Health – August 2008
"Public confidence in the MMR vaccine is now high with more than 8 out of 10 children receiving one dose of MMR by their second birthday...However, low vaccine uptake over the past decade means there is now a large group of children who either haven't been vaccinated or who have received just one dose. These children are susceptible to not only measles but to mumps and rubella as well."
Professor Elizabeth Miller, Head of Immunisation at the Health Protection Agency – August 2008