PARENTS with small children are familiar with the terminology of vaccination - three in one, two in one, RIB, oral polio - and discuss with ease the disease these products prevent. Few, however, are immune from the fear that their child might become seriously ill after receiving a vaccination.
There are risks associated with these products, but they are very low. The risk of serious illness caused by the disease itself is much greater than the risk of illness caused by the vaccination in the case of any product currently in use, according to epidemiological studies.
Vaccinations are in a sense a contradiction - the doctor actually gives the patient a form of the disease as a way to prevent that disease occurring again in the future.
Older vaccine forms used weakened disease viruses, which challenged the person's immune system without putting the person's health at risk. The body's defences responded by killing the virus and in the process created an immunity to the disease.
People of any age who have a healthy immune system can be given near permanent immunity to a wide range of diseases in this way and vaccination has successfully wiped out smallpox worldwide.
Vaccination is more often associated with childhood, however, because protection is needed against diseases such as whooping cough, which is a threat to babies in particular.
The diseases of concern at this age include diphtheria, tetanus, whooping cough, also known as pertussis, and polio. The first three are combined in a "three in one" injection, but there is also a "two in one" which only includes diphtheria and tetanus.
This was introduced because, the pertussis part of the vaccine causes symptoms such as fever and rashes in a higher proportion of children than does diphtheria and tetanus and also because older children do not need boosters against pertussis.
More recent additions to this list include vaccination against measles, mumps, rubella - in a combined MMR vaccination - and a common form of bacterial meningitis in a HIB vaccination.
Vaccination practice, as applied in Ireland, begins when a child is two months old, when the three in one and RIB are given and then repeated at four and six months. Some children react badly to the first three in one. If such is the case, the two in one is used as a substitute booster at four and six months.
The MMR is given at about 15 months and oral polio immunisation is given at six months and then repeated at five years.
Pertussi's is a particular threat to healthy infants up to about one year, but the risks related to the disease - such as development of pneumonia - decline as the child matures. By the time the child is five or six, pertussis holds very little threat for the healthy individual, and thus this part of the vaccine is unnecessary at that age.
The children in Newbridge, having reached five or six, had become due for a final booster against diphtheria and tetanus, and parents would have been offered a two in one for their children. The health board inadvertently administered the three in one product instead.
The substitution would have had very little impact on the typical healthy child, who might experience a slight temperature or soreness at the point of injection. The health board could not have known, however, whether all of the children who received the injections were "typical".
The manufacturers of vaccination products provide doctors with a list of warnings about increased risks for some children, or "contra indications".
One key contra indication is whether the child has had a bad reaction to the pertussis vaccination in the past. A detailed record of the child's immunisations would be needed to show whether this applied to any of the Newbridge children.
Three in ones would generally be avoided if the child had a fever or was "brewing" an illness, something a parent might be alert to. Manufacturers recommend against vaccination in these circumstances.
