Vaccines provide long term protection against a disease. Thanks to vaccines, we have been able to eradicate many life threatening diseases from our society. They work by introducing weakened (attenuated) or dead forms a a pathogen, a live form of a milder pathogen or a preparation of the toxins or antibodies of a pathogen. This triggers an immune response and the body produces antibodies (proteins produced by white blood cells) specific to the antigens that coat the pathogen. these antibodies can then neutralise the pathogen by attaching to white blood cells, allowing them to engulf the pathogen by phagocytosis; or bind to many pathogens, preventing them from entering and so infecting body cells. This response also creates memory cells which stay in the blood (as antibodies do not) so that the next time the pathogen is detected the body can mount a faster immune response. Some vaccines require regular boosters (e.g. tetanus boosters every 10 years) in order to maintain the levels of these memory cells in the blood.
Vaccination programmes can either involve ring vaccination, where the inhabitants of the region where a disease outbreak occurs are all vaccinated so that the disease cannot spread and is isolated (this method was used to control the outbreak of Aphthae epizooticae/foot-and-mouth disease in 2001), or herd vaccination, where the majority of the population is vaccinated so enough people are protected and so cannot carry the disease (usually this means over 85% but is dependent on the disease, e.g. measles requires up to 94%).
Measles
Measles is a disease caused by a virus and is highly infectious, it is spread through droplets in coughs and sneezes. Measles is common in children between 1 and 4 years old. Measles is characterised by an itchy and spotty rash starting behind the ears and spreading over the face and then body with a red-brown colour. The rash is often preceded by red -eyes, cough, fever and white spots inside the mouth. Adults are more likely to have severe complications when they develop measles, these can include diarrohea, pneumonia (1 in 20 child measles cases), severe ear infection and deafness, encephalitis (swelling of the brain which can cause seizures), it can also cause miscarriages and low birth-weight babies of infected women.Rarely people with childhood measles can go on to develop subacute sclerosing panencephalitis (or, less of a mouthful, SSPE) around 7 years after infection which is a degenerative disease of the nervous system and leads to changes in personality, muscle spasms and mental deterioration.
Mumps
Mumps is again a viral infection and is spread in the same way as measles, colds and flu. Mumps causes swelling of the parotid (saliva) glands, causing pain and difficulty swallowing. people with mumps also often have headaches, fever and joint pain. Complications of mumps include: if caught around puberty the painful swelling of the testicles in males or the ovaries and/or breasts in females which can lead to fertility problems in the future; deafness; and the swelling of the brain (encephalitis) and/or spinal cord (meningitis) which if untreated, can go on to cause severe neurological damage.
Rubella (or German Measles) is a viral infection, spread by droplets, and often has a two week lag period before symptoms manifest, with sufferers becoming infectious, a week after catching the disease. Rubella has a characteristic red skin rash which lasts several days, as well as swollen glands, fever and runny nose.Rubella is particularly dangerous if caught by pregnant women in the first 16 weeks of pregnancy, as can cause birth defects in the developing baby such as cataracts, deafness, heart defects, brain damage and liver and spleen damage, together these problems are known as congenital rubella syndrome (CRS).
The MMR vaccine
In 1988 a vaccine was developed against Measles, mumps and rubella, known as the MMR vaccine. The vaccine contains attenuated forms of the measles mumps and rubella viruses and is given as a single injection into the arm or thigh. It is administed to babies aged between 12 and 13 months and a booster is given before starting primary school in the hope of providing herd immunity to the entire population. The three-in-one injection minimises the risk of children developing any of the illnesses in the time between separate jabs. Due to the effects of rubella on pregnant women, non vaccinated women hoping to get pregnant are also given the vaccine.The vaccine provide lifelong immunity and thanks to the vaccine, levels of all three disease fell to an all time low.
Side affects of the injection include: after a week of vaccination, a mild form of measles that lasts for 2 or 3 days and usually includes a rash and fever; after a month of vaccination, a mild form of mumps that again lasts around 2 days and includes swollen glands; stiff and swollen joints of adult women who take the vaccine to protect against rubella; very rarely bruise-like spots may appear this is known as idiopathic thrombocytopenic purpura (ITP) which is linked to the rubella vaccine, however, ITP is far more common in people who catch live forms of measles or rubella that from the vaccine, and there is treatment for the disease. Some children have an allergic reaction immediately after the vaccine, however medical staff who give vaccines are trained to deal with this and can ensure quick treatment of the reaction. People who have been vaccinated with MMR are unable to infect others with any of the diseases.
In 1988 a study was published linking the MMR vaccine to autism and bowel disease, these findings based on the study of a sample of 12 children has since been discredited and recent studies have shown that there is no link between the vaccine and the conditions. There was also worry about the fact that a three-in-one vaccine would put too much strain on a child's immune system. Unfortunately, the study put parents in a very difficult situation as the claims were spread by the media and so many were insure whether to vaccinate their children. This has left an estimated 2 million people at risk from the diseases and the current epidemic in Swansea has seen a man dead due to measles.
http://www.nhs.uk/Conditions/vaccinations/Pages/mmr-vaccine.aspx
http://www.cdc.gov/measles/
http://www.cdc.gov/mumps/
http://www.cdc.gov/rubella/
http://news.bbc.co.uk/1/hi/health/1808956.stm
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