Nasopharyngeal pneumococcal carriage of children attending day care centers in Korea: comparison between children immunized with 7-valent pneumococcal conjugate vaccine and non-immunized.

To confirm the effect of 7-valent pneumococcal conjugate vaccine (PCV7), pneumococcal nasopharyngeal (NP) carriage was compared between vaccinated (3 + 1 doses PCV7) and non-vaccinated children. Vaccinated subjects were recruited from highly vaccinated regions (≥ 60%), Seoul and Incheon whereas control subjects were recruited from Jeju Island where vaccination rates are low (< 15%). NP swabs were obtained from 400 children aged 18-59 months. Serotype and antibiotic susceptibility was analyzed. Pneumococcal carriage rate was 18.0% (36/200) and 31.5% (63/200) for the vaccinated and control group, respectively. Among those vaccinated, 41.7% (15/36) of the serotypes were vaccine-related type (VRT: 6A, 6C, 19A) with the most common serotype 6C. The next common type was non-typable/non-capsule 30.6% (11/36) followed by non-vaccine type 16.7% (6/36) and vaccine type (VT) serotypes were found in only 11.1% (4/36). In contrast, 52.4% (33/63) of the isolates in the control group were VT. Resistance rates for penicillin and erythromycin were lower in the vaccine group (vaccine vs control; penicillin 45.2% vs 71.4%, erythromycin 74.2% vs 90.5%, P < 0.05). Multi-drug resistance was also lower in vaccinated subjects (vaccine vs control; 45.2% vs 69.8%, P < 0.05). PCV7 reduces carriage in VT which leads to replacement of pneumococci by antibiotic susceptible VRT or non-vaccine type strains.

The immunogenicity and safety of DTaP interchangeable immunization among Korean children.

Since the production of various vaccine formulations by different pharmaceutical companies and interruptions in vaccine supply cannot be fully regulated, problems caused by DTaP interchangeability may occur. However, the interchangeability data on the first primary series of DTaP vaccination have not been well described. In this study we investigated immunogenicity and overall safety of diphtheria, tetanus, pertussis in children who had adventitiously received an interchangeable DTaP vaccination. A total 97 of participants were enrolled (mean age, 11 months). High immunogenicity (1.8 ± 0.4 IU/mL, 100%) was noted against diphtheria toxoid, and similar high immunogenicity (3.2 ± 2.1 IU/mL, 100%) was noted against tetanus toxoid. Immunogenicity against pertussis antigen was significantly greater in the interchangeable vaccinated group compared to the control group, and 57% of the interchangeable vaccinated subjects achieved high levels of protective immunity (45.2 ± 21.5 E U/mL). No serious adverse effects were noted, and most adverse effects resolved without treatment. The immunogenicity against each antigen was high in patients who were interchangeably vaccinated for DTaP. Our results provide clinical evidence affirming the non-inferiority of interchangeable vaccination when it cannot be avoided such as in limited vaccine supply situations or different prices.

Immunogenicity and safety of diphtheria-tetanus vaccine in pre-adolescent and adolescent South Koreans.

This study was conducted to compare the immunogenicity and safety of diphtheria-tetanus (Td) vaccine between pre-adolescents aged 11-12 years and adolescents aged 13-18 years. A total of 277 subjects (132 pre-adolescents and 145 adolescents) participated. After vaccination, all subjects (100%) in both groups exhibited seroprotective antibody levels (> or =0.1I U/mL) against diphtheria or tetanus toxoids. Although local adverse events following vaccination were more frequently observed in the pre-adolescent group than in the adolescent group (p=0.006), these events resolved within 7 days. Our study shows Td vaccination at age 11-12 years to be immunogenic and tolerable.