By: Todd Neale, Senior Staff Writer, MedPage Today
03 December 2010
Although preterm infants have a response to seven-valent pneumococcal conjugate vaccine (PCV7), it does not result in the antibody levels achieved by full-term infants for all serotypes, researchers found.
After an initial three-dose immunization series by age 4 months, antibody titers increased for both preterm and term infants, but preterm birth was associated with a lower concentration of antibodies against serotype 23F (P<0.01), according to Samantha Moss, MD, of the Royal Victoria Infirmary in Newcastle upon Tyne, England, and colleagues.
By 12 months, antibody concentrations had declined for six of seven serotypes covered by the vaccine in both full-term and preterm infants, but preterm birth was associated with significantly lower concentrations of antibodies against five of the seven vaccine serotypes (P<0.05), the researchers reported in the November issue of Clinical and Vaccine Immunology.
A fourth booster dose at 12 months induced a robust response in most infants.
“Given that the majority of infants had an adequate response to a fourth dose, it is likely that the reduced response of our preterm cohort is due at least in part to immunological immaturity,” Moss and her colleagues wrote.
“A practical solution would be to offer to examine the response to PCV7 in preterm infants post-primary immunization and, if they are unprotected, to offer them an early booster dose,” they wrote.
However, because of the significant cost and effort required to identify at-risk infants, they continued, “an alternative approach would be to ensure that household contacts were immunized against pneumococcus.”
Moss and her colleagues examined the responses of 133 preterm and 54 full-term infants immunized with PCV7 at 2, 3, and 4 months according to the U.K. immunization schedule at the time. The study was completed before the introduction of 13-valent pneumococcal vaccine.
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