Immunogenicity and effectiveness of Haemophilus influenzae type b conjugate vaccine in HIV infected and uninfected African children
ABSTRACT The quantitative (anti-Hib capsular polysaccharide antibody concentrations; anti-HibPS) and qualitative (bactericidal activity and avidity) aspects in immune responses to Haemophilus influenzae type b polyribosyl ribitol phospshate-CRM(197) conjugate vaccine (HibCV; HibTiter) were evaluated in 66 HIV infected children not receiving anti-retroviral therapy and 127 HIV uninfected children. Surveillance was conducted for invasive Hib disease in a cohort of 39,865 (approximately 6.4% of whom were HIV infected) children from March 1998 to June 2004. HIV infected children had lower anti-HibPS geometric mean antibody concentrations 1 month post-immunisation than HIV uninfected children (P<0.00001) and were less likely to have anti-HibPS antibody concentrations of >or=1.0 microg/ml (RR 0.54; 95% CI 0.43-0.69). A lower proportion of HIV infected children than HIV uninfected children (RR 0.78; 95% CI 0.66-0.93) had measurable anti-Hib serum bactericidal activity (SBA) and the HibPS antibody concentration required for 50% killing of Hib bacteria was greater among HIV infected than HIV uninfected children (P=0.001). The estimated risk of HibCV failure was 35.1-fold greater (95% CI 14.6-84.6) amongst HIV infected than HIV uninfected children.
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ABSTRACT: To measure the disease burden and epidemiological characteristics of invasive Haemophilus influenzae in rural Mozambican children. As part of the clinical management of children admitted to Manhiça District Hospital, blood and cerebrospinal fluid samples were collected between May 2001 and April 2005 for children aged <5 years. The level of antibiotic resistance of the isolates was analysed. During the surveillance period, there were 106 episodes of invasive H. influenzae disease. The estimated minimum incidence rate of invasive disease among children <5 years of age was 125/100,000 per child-year-at-risk. Fifty-six (59/106) per cent of cases were infants aged 3 to <12 months. Confirmed meningitis explained 16% of the episodes (n = 17) but was probably underestimated, as meningitis surveillance was not well implemented in the setting during the study. The case-fatality-rate was 21%, being highest among children with meningitis (odds ratio = 4.38, P = 0.011). Resistance to the antibiotics most commonly used in Mozambique was high--chloramphenicol 39%, ampicillin 35% and cotrimoxazol 74%-- and had increased over the years (P < 0.001 for chloramphenicol). Invasive H. influenzae disease is of considerable public health importance in Mozambique; implementing H. influenzae type b vaccination in sub-Saharan Africa has the potential to increase child survival.Tropical Medicine & International Health 06/2008; 13(6):818-26. DOI:10.1111/j.1365-3156.2008.02061.x · 2.30 Impact Factor
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ABSTRACT: Although vaccine-preventable diseases are common in HIV, concerns about vaccine safety and lack of efficacy in this patient population often lead to missed opportunities for vaccination. In this article, we review the literature regarding vaccine risks and benefits and offer recommendations regarding their use and timing in patients with HIV infection.Current Infectious Disease Reports 04/2006; 8(2):151-61. DOI:10.1007/s11908-006-0011-y
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ABSTRACT: Haemophilus influenzae type b (Hib) conjugate vaccine is not perceived as a public health priority in Africa because data on Hib disease burden and vaccine effectiveness are scarce. Hib immunization was introduced in Kenyan infants in 2001. To define invasive Hib disease incidence and Hib vaccine program effectiveness in Kenya. Culture-based surveillance for invasive Hib disease at Kilifi District Hospital from 2000 through 2005 was linked to demographic surveillance of 38,000 children younger than 5 years in Kilifi District, Kenya. Human immunodeficiency virus (HIV) infection and Hib vaccination status were determined for children with Hib disease admitted 2002-2005. Introduction of conjugate Hib vaccine within the routine childhood immunization program at ages 6, 10, and 14 weeks beginning November 2001. Incidence of culture-proven Hib invasive disease before and after vaccine introduction and vaccine program effectiveness. Prior to vaccine introduction, the median age of children with Hib was 8 months; case fatality was 23%. Among children younger than 5 years, the annual incidence of invasive Hib disease 1 year before and 1 and 3 years after vaccine introduction was 66, 47, and 7.6 per 100,000, respectively. For children younger than 2 years, incidence was 119, 82, and 16 per 100,000, respectively. In 2004-2005, vaccine effectiveness was 88% (95% confidence interval, 73%-96%) among children younger than 5 years and 87% (95% confidence interval, 66%-96%) among children younger than 2 years. Of 53 children with Hib admitted during 2002-2005, 29 (55%) were age-ineligible to have received vaccine, 12 (23%) had not been vaccinated despite being eligible, and 12 (23%) had received 2 or more doses of vaccine (2 were HIV positive). In Kenya, introduction of Hib vaccine into the routine childhood immunization program reduced Hib disease incidence among children younger than 5 years to 12% of its baseline level. This impact was not observed until the third year after vaccine introduction.JAMA The Journal of the American Medical Association 09/2006; 296(6):671-8. DOI:10.1001/jama.296.6.671 · 30.39 Impact Factor