Immune Compromise Due to Immaturity

It is widely recognized that the newborn immune system has limited functionality. The consequences of immune compromise due to immaturity are seen, for example, in high mortality rates due to infection in historical times, and in poor communities today. It is important to understand neonatal and infant immune compromise in qualitative and quantitative detail, so that immunization campaigns can be delivered effectively – we want to protect the infant as early as possible, yet there is no point immunizing infants before their immune system is able to respond. There is even a risk that early exposure to antigen will prevent an effective immune response later. Immune compromise in the neonate and infant is a physiological state, not a disease, and we should be cautious about “treatment.” It is worth considering the possible evolutionary pressures that have led us to be born into a pathogen-rich environment with immune function that appears to be compromised. Could it be that evolutionary pressures have selected the best balance between different threats, and if we stimulate the immune response excessively at this stage in life there will be adverse consequences to health and reproductive fitness later in life?