[Study on the immunity of diphtheria in children at county level with different 4-vaccine coverage rates based on the results from "National Immunization Program Review" in 2004].
OBJECTIVE
To investigate the immunity level of diphtheria antibody among children living in the areas where different coverage rates of 4-vaccines stratified by results of national immunization program (NIP) reviewed in 2004.


METHODS
According to data from 4-vaccine coverage rates of NIP reviewed in 2004, 3 levels could be set. We randomly selected 2 counties at each level and then 10 villages from each county with 42 children involved who were born between 1992 and 2003. ELISA quantitative method was used to test IgG of diphtheria antitoxin.


RESULTS
(1) The positive rate of diphtheria antitoxin was only 49.6% with the highest as 78.1% and lowest as 33.0%. There was a significant decreasing trend of this positive rate with the increase of age. The highest (61.2%) fell in the group that were born in 2003 and the lowest (37.6%) was seen among children born in 1992 to 1995. (2) Geometric mean concentrations (GMCs) was only 0.48 IU/ml with a trend of decrease when age was increasing. There was no GMCs peak seen in children who were at the age of boosting, as expected. (3) Positive rates of children born between 2001 and 2003 were lower than 62% while the diphtheria-pertussis-tetanus (DPT) vaccine coverage rates were all higher than 90%. (4) There was no significant difference of diphtheria antitoxin positive rates between children with eligible routine immunization (58.1%) and those were ineligible (59.6%).


CONCLUSIONS
Other than some specific ones, children from most of the investigated counties had a low level of antibody against diphtheria. The coverage rate of DPT vaccine did not necessarily reflect the immunity against diphtheria, suggesting the increase of immunity against diphtheria an urgent task to be taken care of.
Wang
Hua-qing
HQ
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Guo
Xin
X
Chen
Li-juan
LJ
Yang
Jie
J
He
Jing-guo
JG
Luo
Ming
M
He
Xiong
X
Zhou
Yu-qing
YQ
Cao
Ling-sheng
LS
Lu
Yong
Y
Yin
Da-peng
DP
Chen
Yuan-sheng
YS
Xia
Wei
W
Liang
Xiao-feng
XF
D000293:Adolescent; D017677:Age Distribution; D000907:Antibodies, Bacterial / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D002681:China; D004165:Diphtheria / Q000276:immunology* / Q000517:prevention & control*; D004166:Diphtheria Antitoxin / Q000276:immunology*; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male
D000907:Antibodies, Bacterial; D004166:Diphtheria Antitoxin; D015721:Diphtheria-Tetanus-Pertussis Vaccine