Ten people have become infected with the potentially deadly meningococcal B virus after they were fully vaccinated against it, prompting the Ministry of Health to consider a fourth vaccination jab for young children.
Medsafe is expected to announce in the next few days whether a fourth immunisation shot will be
introduced for babies.
National meningococcal vaccine strategy director Dr Jane O'Hallahan said the extra vaccine was only being considered for infants because they were the most vulnerable to the disease.
"We know that infants generally respond to a lesser extent to immunisations in the first year of life than older children and therefore it was likely that a fourth dose may be required to boost their level of immunity and give them longer protection."
Of the nine other patients who contracted the virus, seven were over five-years-old and two were under five.
Dr O'Hallahan said the fourth shot was not being considered for patients older than infant age because of the relatively small number who had contracted the illness.
The vaccination programme was rolled out to under 20-year-olds in July 2004, with full immunisation due to be complete after three vaccination shots.
More than 2.8 million doses have been administered and 890,000 people have had all three doses.
Of the ten people who contracted the virus after having all three doses, two were admitted to intensive care, and all had to be treated in hospital. All patients made a full recovery.
It takes up to 28 days after the last dose for a person to be fully immunised and protected.
Dr O'Hallahan said: "I think the vaccine is showing itself to be effective. The vaccine is having a good impact on the epidemic, however we've always been concerned around the infants who have immature immune systems ... and require an additional dose to give them the level of protection that older children have gained."
She said if people requested a further shot from their doctor, they could get it.
But there was no evidence that a fourth vaccination would have benefited the nine older patients who contracted the disease, Dr O'Hallahan said.
The total number of all cases of meningococcal disease in the year to November last year was 222, with 14 deaths. The average number of cases a year for the past five years was 490.
- NZPA
