Pneumococcal polysaccharide vaccine at 12 months of age produces functional immune responses.
BACKGROUND
Infections with Streptococcus pneumoniae (pneumococcus) are a cause of significant child mortality. Pneumococcal glycoconjugate vaccines are expensive and provide limited serotype coverage. The 23-valent pneumococcal polysaccharide vaccine (Pneumovax) might provide wider serotype coverage but is reported to be weakly immunogenic in children less than 2 years of age. We have previously reported that Pneumovax administered to healthy 12-month-old Fijian infants elicits significant serotype-specific IgG responses. However, the functional capacity of these responses in 12-month-old infants is not known.


OBJECTIVE
We sought to assess the functional, serotype-specific immune response of 12-month-old infants after immunization with Pneumovax.


METHODS
Functional responses of 12-month-old infants were assessed by using the opsonophagocytic and antibody avidity assay against 8 serotypes and 23 serotypes, respectively.


RESULTS
Seventy-one percent of infants produced strong opsonophagocytic activity against 4 of 8 serotypes, and 30% produced high-avidity serotype-specific IgG antibodies to 10 of 23 serotypes at 2 weeks after Pneumovax. Responses were protective for most serotypes that cause disease in Western countries, whereas responses to most of the epidemiologically relevant serotypes for developing countries were low.


CONCLUSIONS
This is the first comprehensive study evaluating the functional antibody response to Pneumovax in 12-month-old infants. Pneumovax induced functional antibody responses to several serotypes causing disease in Western countries but induced poorer responses to serotypes that are responsible for the majority of disease in developing countries. Pneumovax might be of benefit in some populations, but further studies are required before this can be recommended in developing countries.
Pneumococcal Laboratory, Murdoch Childrens Research Institute, Melbourne, Australia.
Paul V
PV
Licciardi
Anne
A
Balloch
Fiona M
FM
Russell
Robert L
RL
Burton
Jisheng
J
Lin
Moon H
MH
Nahm
Edward K
EK
Mulholland
Mimi L K
ML
Tang
D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D003906:Developing Countries; D000939:Epitopes; D005260:Female; D005367:Fiji; D005500:Follow-Up Studies; D006801:Humans; D007114:Immunization; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007223:Infant; D008297:Male; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D022541:Streptococcal Vaccines / Q000008:administration & dosage*; D013296:Streptococcus pneumoniae / Q000276:immunology*
D000907:Antibodies, Bacterial; D000939:Epitopes; D007074:Immunoglobulin G; D022242:Pneumococcal Vaccines; D022541:Streptococcal Vaccines