Immunogenicity, safety and tolerability of vaccinations in premature infants.

Infections are more common and generally more severe in neonates and young children than in older children and adults, mainly because immune defenses are functionally impaired in early life. The seriousness of the infectious problems of premature infants (PIs) is proportional to how premature they are, but irrespective of this, they are more serious than those of full-term infants because their immune system is compromised to a greater extent. This review analyzes our knowledge of the characteristics of the developing immune system, the impact of possible impairments on immunization, the real response of PIs to vaccines and the safety and tolerability of different vaccines. Overall, the data indicate that PIs should follow the same vaccination schedule as that generally used for full-term infants, without correcting for prematurity and regardless of birthweight. However, there is an urgent need for further studies concerning the use of recently marketed vaccines and those that will be marketed in the near future.