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pubmed:abstractText |
In developing countries, Haemophilus influenzae type b is a major cause of meningitis and pneumonia in the 1st year of life. The safety and immunogenicity of a Haemophilus influenzae type b polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) were evaluated in two studies of Gambian infants. In the first study, 131 infants were recruited and randomized into three groups to receive PRP-T at 1 and 3 months (group A), PRP-T at 2 and 4 months (group B) or no PRP-T (group C). The liquid form of PRP-T was used. The geometric mean titre (GMT) of anti-PRP antibody 1 month after the second dose was 0.26 microgram/ml in group A and 0.41 microgram/ml in group B. In the second study, 66 infants were given PRP-T in the lyophilized form at 2, 3 and 4 months of age. The GMT 1 month after the first dose was 0.09 microgram/ml, after the second 0.74 microgram/ml and after the third 2.32 micrograms/ml. After the third dose, 72% of children had antibody levels greater than 1.0 microgram/ml and 93% greater than 0.15 microgram/ml. No serious side-effects were observed and the rate of adverse reactions was consistent with the concurrent administration of diphtheria-tetanus-pertussis (DPT) vaccine.
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pubmed:otherAbstract |
PIP: In Sukuta, Gambia, in 1989, 128 newborns were randomly allocated to receive the liquid form of the Haemophilus influenzae type b (Hib) polysaccharide-tetanus toxoid (PRP-T) vaccine at 1 and 3 months (group A), 2 and 4 months (group B), or not to receive the vaccine (group C). All these children also received the oral polio vaccine and the diphtheria-pertussis-tetanus (DPT) vaccine. In 1990, in Bakau, Gambia, 66 infants received the lyophilized form of the PRP-T vaccine at the same time as they received DPT vaccine: 2, 3, and 4 months. The investigators aimed to determine the safety and immunogenicity of PRP-T as a forerunner to the upcoming PRP-T efficacy trial in Gambia. In the 1989 study, the geometric mean titer (GMT) of anti-PRP antibody 1 month after the second dose was higher in group B than in group A (0.41 vs. 0.26 mcg/ml). In the 1990 study, the GMT of anti-PRP antibody was 0.09 mcg/ml after the first dose, 0.74 mcg/ml after the second dose, and 2.32 mcg/ml after the third dose. One month after the final dose, the lyophilized PRP-T vaccine yielded higher antibody levels than the liquid form. For example, 72% of infants in the lyophilized group had an antibody level greater than 1 mcg/ml compared with 18% for the liquid group. 93% of all infants in groups A and B had antibody levels above 0.15 mcg/ml, the level considered to provide immediate protection, compared with 53% for the liquid group. Serious side effects were not observed. The rate of adverse reactions correlated with the concurrent delivery of DPT vaccine. Advantages of the PRP-T vaccine include: it mixes well with DPT; if administered in a three-dose schedule to Gambian infants, it is safe and elicits a protective antibody response in most infants; and it also protects against Hib infection, a major cause of meningitis and pneumonia in infants and an important cause of major childhood-acquired disability in developing countries.
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