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The Irish Times – April 28, 2005


How can we protect babies from infections?



Because of their different immune systems we need to design new vaccines for infants, writes Dick Ahlstrom.
Newborn infants are not the same as adults so why should we assume that an infant’s immune system is the same as an adults?
A Dublin based researcher is studying the surprising level of difference between the way infants and adults respond to infections.
Understanding these differences is crucial as it influences the development of new vaccines, argues immunologist Prof Denis Reen. It also allows us to gauge how well-protected newborns are against common infections.
Reen is based in the Children’s Research Centre which has labs in UCD’s department of paediatrics at the Conway Institute of Biomolecular and Biomedical Research and in Our Lady’s Hospital for Sick Children, Crumlin. He leads research into the capabilities of our immune system in early life and how it responds to vaccination.
Tonight he gives a free public Science Today lecture at the RDS Concert Hall in Ballsbridge entitled, “How Well Are We Protected Against Infections and Allergies in Early Life?” The event is organised jointly by The Irish Times and the Royal Dublin Society in conjunction with the Irish Society for Immunology that tonight will present Reen with its annual Public Lecture Award.
Tonight Reen will highlight the obvious benefits society has received from childhood vaccination programmes but he will also ask whether we have got it wrong when it comes to infants.
“We have to significantly modify our approach to vaccine development and use in early life,” he says. “We have found that the newborn immune system is much different to what we assumed.”
He and his team use newborn immune cells recovered from umbilical cord blood to study the immature immune response to infection. He has found that these cells in a newborn are “fundamentally underdeveloped” and react much differently than in an adult or even a year-old baby.
Infants are not young children and young children are not adults, he says. We should not be surprised then to discover major differences in how the immune system responds at different ages.
Babies typically receive MMR vaccinations when they are between 12 and 15 months old, he says. “Why don’t we start protecting infants at birth? Infants can catch measles at less than 12 months. The reason is the vaccinations don’t work (in newborns),” he says.
Naive immune cells “are more tolerant or switched off”, he says, and they need a much stronger stimulation to deliver an adequate response. “The effect is if we put in a stimulus and take a naive immune cell and compare it to one from an adult, we get a level of output with the adult cell but a much weaker (immune) response from a newborn cell.”
Vaccines of the future will not contain material from bacterial or viral sources, they will be genetically engineered, he believes. It will become essential to have a better understanding of how the infant immune system responds to new vaccines.
“We have to rethink our approach towards getting early life immunity,” he says. “Why can’t we vaccinate at birth?” Can we move towards where we can give vaccines at birth,” he asks.
Reen tonight will also discuss the sharp rise in the numbers of children affected by allergies and asthma. “Allergies are very much a growing phenomenon,” he says.
Ironically, this increase is most acute in rich western societies where there is a higher level of bacterial cleanliness. “In less hygienic societies (allergies) are less of a problem.” Research suggests that the immune system is less likely to respond in an allergic fashion when there are frequent and repeated challenges to it.