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 Original Articles |
| Immunogenicity and Safety of Haemophilus influenzae type b Polysaccharied-Tetanus Toxoid Conjugate Vaccine (PRP-T) in Korean Infants |
| Jung Soo Kim*, Seog Beom Cho, Hong Ro Lee, Sun Kyu Park, Pyoung Han Hwang |
| Department of Pediatrics, Institutd for Medical Science, Chonbuk National University Medical School, Chonju, Chonbuk, Korea |
Vol.28 Num.3 (p225~232)
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Background : Vaccines against invasive H. influenzae type b (Hib) are based on stimulating antibodies to capsular polysaccharide antigen such as polyribosyl ribitol phosphate (PRP). Several PRP conjugate vaccines have been developed in order to improve the immunogenicity of PRP in infants and young children.
This study was performed to evaluate the immunogenicity and safety of PRP-T, a cinjugate vaccine that consists of PRP covalently linked to tetanus toxoid, in Korean infants.
Methods : Eighty two Korean infants were enrolled in this study. Infants were divided into 2 groups such as 2 month group(40 cases) : infants received 3 doses of PRP-T, DTP and TOPV at 2, 4 and 6 months of age, and 6 month group(42 cases): infants received only 2 doses of PRP-T vaccine one month apart.
Local and systemic adverse reactions were monitored for 3 consecutive days of each immunization, and immunogenicity of vaccine components was evaluated by measuring specific antibodies in the sera of vaccinees. Anti-PRP antibody was measured with a Farr-type radioimmunoassay.
Results : In 2 month group, gemetric mean titer(GMT) of anti-PRP antibodies was significantly increased after PRP-T vaccination from 0.14μg/mL at pre-vaccination to 11.49μg/mL after 2 doses and 20.34μg/mL after 3 doses.
In 6 month group, GMT of anti-PRP antibodies was also markedly increased after PRP-T vaccination from 0.09μg/mL at pre-vaccination to 4.93μg/mL and 16.06μg/mL after 1 and 2 doses of vaccination respectively.
Anti-PRP antibody ≥ 0.15μg/mL which has been considered as a minimal protective value after natural infection was observed in 5 cases(12.5%) of 2 month group and 2 cases(4.8%) of 6 month group at pre-vaccination. All vaccinees obtained anti-PRP antibody level ≥ 0.15μg/mL after 2 doses of PRP-T vaccine.
Anti-PRP antibody ≥ 1.0μg/mL, which has been accepted as a long term protective value after immunization, was obtained in 85% (34/40) after 2 doses, and 87.5% (35/40) after 3 doses in 2 month group, while 85.7% (36/42) after one dose and 100% (42/42) after 2 doses in 6 month group.
The incidence of systemic and local adverse reactions following PRP-T vaccination was not high. Fever, the most common systemic reaction, was observed in 11.3% (23/204), followed by diarrhea (4.9%) and irritability (3.0%). Local reactions such as induration and erythema were observed exclusively on DTP injection sites (13.3% on DTP site versus 1.5% on PRP-T site).
Conclusion : H. influenzae type b vaccine(PRP-T) was immunogenic and safe in Korean infants, and can be used concurrently with DTP and TOPV using different syringes on different injection sites. 3 doses of PRP-T vaccine will be needed in 2 month group, while 2 doses are enough after 6 months of age.
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Keywords : H. influenzae type b, Vaccine, Immunogenicity, DTP |
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