Vaccination is a safe and effective way of preventing life-threatening diseases, but national vaccination rates remain too low, writes Dr Eve O'Toole.
Immunisation has been proven to be an extremely effective way of preventing some infectious diseases; for example, measles, mumps, rubella, Haemophilus influenza type b (Hib), meningitis C, diphtheria, whooping cough, tetanus and polio. More lives have been saved through immunisation than by any other public health intervention, apart from the provision of clean water. This service is provided free to all children through the primary immunisation programme and the schools immunisation programme.
Implementation of a vaccination programme is a complex procedure. It involves sourcing the vaccine, delivery of the vaccine to the relevant geographical areas and organising healthcare professional to implement the programme.
One of the largest problems with all vaccination programmes is achieving high uptake rates of the vaccine.
To prevent an outbreak of a vaccine preventable disease, 95 per cent of the susceptible population needs to be immunised. This is referred to as herd immunity.
The national immunisation rates fall short of this target. For the last quarter of 2004 immunisation uptake rates at 12 months are: 84 per cent for diphtheria, whooping cough, tetanus, Hib and Polio (five in one), 84 per cent for meningitis c (Men C), and 83 per cent for measles mumps rubella (MMR1) at 24 months.
There is a myriad of reasons why' parents do not bring their children for vaccination or consent to vaccination. A study was carried out in the HSE midland area to determine the view of parents on immunisation. This study highlighted a lack of knowledge among parents about vaccines and vaccine-preventable diseases. In particular, parents were not always aware of the complications associated with these diseases.
Most notable was the fact that parents felt they did not have enough information to make an informed choice.
The preferred method of imparting information is by direct verbal communication with either a nurse or a doctor.
Parents were not happy to receive educational material alone, such as information leaflets. An interesting finding was that most parents felt they would like to have their children vaccinated and there were very few conscientious objectors.
The vaccine-preventable diseases are serious and life-threatening. For example, one in 15 individuals infected with measles will develop complications which include: ear infections, pneumonia, inflammation of the brain, long-term disability and even death.
A measles vaccine was introduced into Ireland in 1985 and replaced by the MMR vaccine in 1988. National uptake rates of the vaccine fall short of the 95 per cent needed to prevent an outbreak.
As a result, an outbreak of measles occurred in 2000, mainly affecting the Dublin area.
There were 1,603 cases of measles and three children died. In 2003 there was a smaller outbreak of 576 cases, proportionally the highest rate occurred in the midland area.
One reason for the low uptake of the MMR vaccine is concern among parents regarding unsubstantiated links between the MMR vaccine and autism and Crohn's disease. Scientific evidence has shown that there is no link between MMR vaccine and either Crohn's disease or autism. A comprehensive study carried out in Denmark probably represents the best evidence to date that there is no association between MMR and autism.
The safest option therefore is to have your child vaccinated. For parents who have specific concerns they should contact their GP.
The Haemophilus influenza type b (Hib) vaccine was introduced in 1992. Hib can cause the following diseases: otitis media, meningitis, pneumonia, septicaemia, epiglottitis, septic arthritis, cellulitis and osteomyelitis.
The most common is meningitis. Since the introduction of the Hib vaccine the number of cases of Hib meningitis has been reduced from approximately 100 cases per year in the late 1980s to less than 10 cases annually until 2002.
Since 2002 there has been a small increase in the number of cases of Hib meningitis in children aged under 15, with seven in 2002, 10 in 2003, nine in 2004 and 11 to date in 2005. The fact that some of those cases occurred in previously immunised children is a cause for concern.
This is referred to as a vaccine failure. There were between one and four vaccine failures per year in 1996-2003.
This figure increased to six in 2004 and in 2005 to date there have been 10 cases of Hib in fully-vaccinated children.
This has led to the recent decision to introduce a booster Hib vaccine, which will be offered to all children aged from six months up to the fourth birthday, as they are most at risk. Immunisation is free. This campaign is due to start next month. It is important to remember that no vaccine is 100 per cent effective.
The HSE strongly advocates vaccination as it is a safe and effective way of preventing life-threatening illness.
Dr Eve O'Toole works in the Population Health Directorate at the Health Service Executive.