Abstract
BackgroundVaccination is still one of the most important methods to control and prevent childhood infections including diphtheria and pertussis. This study evaluated the level of diphtheria (DT) and pertussis (PT)-related antibodies among children with pneumonia in Ji’nan, China.MethodsA total of 484 sera of children from 1 day to 13 years of age were collected from 2014 to 2015 in Ji’nan. Children with recent history of pertussis were excluded from this study. Anti-DT and PT IgG concentrations were measured by ELISA (Euroimmun, Lübeck, Germany).ResultsOf the 484 subjects tested, the overall positivity rate of anti-DT IgG (≥0.1 IU/ml) was 48.97%, and the highest positivity rate of anti-DT IgG (68.55%) and proportion with long term protection (23.27%) were observed in children aged 6 m- < 3 y. For anti-PT IgG, 334 subjects (69.01%) had anti-PT IgG levels below the lower limit of detection (5 IU/ml). Even with detectable anti-PT antibodies, the majority (115/150, 76.67%) of them had antibody levels of 5- < 40 IU/ml. The highest proportion of subjects with detectable anti-PT IgG (≥5 IU/ml) was observed in children aged < 6 m (44.36%), then the proportion continually decreased to 15.0% at 3 y- < 6 y (χ2 = 24.05, p < 0.0001). The highest positivity rate (≥40 IU/ml) was only 8.27% in children aged < 6 m. Subjects with an anti-PT IgG ≥100 IU/ml were observed in all the groups and there were no significant differences in the proportions of subjects with a level ≥ 100 IU/ml among these age groups (χ2 = 2.572, p = 0.4624). A total of 5 subjects had anti-PT IgG ≥100 IU/ml (≥1 years post pertussis vaccination) which was considered to be indicative of a recent pertussis infection.ConclusionsWe demonstrated low antibody levels and protection against pertussis in our study population. The anti-PT IgG maintained a low level throughout all age groups, and even no immune responses were observed after the basic immunization and booster. Our study supported the need to reevaluate the immune response of DTP vaccine which was used in Shandong province after 2010.
Highlights
Vaccination is still one of the most important methods to control and prevent childhood infections including diphtheria and pertussis
A total of 17 subjects were unknown for the history of vaccination against diphtheria or pertussis
Subjects with an anti-PT IgG ≥100 international units per milli-liter (IU/ml) were observed in all the groups, and there were no significant differences in the proportions of subjects with a level ≥ 100 IU/ml among these age groups (χ2 = 2.572, p = 0.4624)
Summary
Vaccination is still one of the most important methods to control and prevent childhood infections including diphtheria and pertussis. Diphtheria and pertussis, caused by Corynebacterium diphtheria and Bordetella pertussis, are highly infectious and vaccine-preventable respiratory diseases [1, 2]. Diphtheria and pertussis vaccination significantly reduced the incidence of these diseases. Pertussis has re-emerged in some developed countries that maintain high vaccine coverage [3]. There was a 50-y high of 48,277 cases of pertussis in the United States in 2012 [4]. In 2012, according to the Pan American Health Organization/World Health Organization (PAHO/WHO) estimation, there were 50 million cases of pertussis which led to 300,000 deaths worldwide [5]. Pertussis remains one of the leading causes of vaccine-preventable deaths in the world today
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