A phase II, randomised clinical trial to demonstrate the non-inferiority of low-dose MF59-adjuvanted pre-pandemic A/H5N1 influenza vaccine in adult and elderly subjects.

BACKGROUND: Effective planning and preparedness against a possible future A/H5N1 influenza pandemic is a major global challenge. Because dose sparing strategies are required to meet the global demand for vaccine, efforts have focused on the development of adjuvanted vaccine formulations of relatively lower antigen content. AIM: This study aimed to demonstrate the non-inferiority of a low-antigen-dose (3.75 µ) [DOSAGE ERROR CORRECTED] A/H5N1 pre-pandemic vaccine compared with a licensed, higher-dose (7.5 mg) formulation in adult and elderly subjects. Immunogenicity was assessed according to European and U.S. licensure criteria. METHODS: A total of 722 subjects were randomized in equal numbers to receive either the licensed or low-dose formulation. All subjects received two vaccine doses administered three weeks apart. Immunogenicity was assessed three weeks after the administration of each vaccine dose by hemagglutination inhibition (HI), single radial haemolysis (SRH) and microneutralization assays (MN). Local and systemic reactions were assessed over a seven day period post-vaccination. Adverse events were recorded throughout. RESULTS: The low-dose vaccine was demonstrated to be non-inferior to the licensed formulation in terms of antibody titres against the vaccine strain. All three European licensure criteria were met by adult subjects in response to the low-dose vaccine; two criteria were met by the elderly age group. Cross-reactive antibodies were detected against the heterologous A/H5N1 antigen strains A/Indonesia/05/05 and A/turkeyTurkey/01/05. Both vaccines were generally well tolerated by both age groups. CONCLUSION: These data demonstrate that a low antigen dose in combination with MF59 adjuvant is adequate for the routine pre-pandemic immunization of adult and elderly subjects.

Persistent factor VIII inhibitors and orthopaedic complications in children with severe haemophilia A.

Persistence of inhibitors against factor VIII (FVIII) may be a risk factor that increases physical disability in haemophilia A (HA) patients. This study aimed to evaluate prevalence of FVIII inhibitors in previously treated children with severe HA and the impact of persistent inhibitors on knee joint status and lumbar bone mineral density (BMD). Fifty children with severe HA, FVIII <1%; aged 5-16 years were enrolled in this study; they received plasma-derived FVIII on-demand treatment for 50-250 exposure days (EDs). Inhibitors were checked at basal visit and were followed up for 1 year, using Bethesda assay. Cross-sectional clinical scoring and radiological evaluation of the knee joint (by Arnold-Hilgartner staging and Pettersson score), along with lumbar BMD by Dual Energy X-ray Absorptiometry (DEXA) were performed. Patients with persistent inhibitors for 1 to 5 years, median 2.5 years, were 10 (20%). Six had high titre and none of them had completely normal knees, seven had advanced knee arthropathy and six had low lumbar BMD in comparison to 2 and 8 of the 40 patients without inhibitors respectively (P < 0.05). Persistence of inhibitors for more than 2 years without immuno-prophylaxis was a risk factor for joint damage. Low lumbar BMD was found in 88.9% of patients with stages four and five knee arthropathy and in 66.7% of patients with positive hepatitis C. Severe HA children in this Egyptian study had a relatively low prevalence of persistent FVIII inhibitors, which, if not treated, may increase the risk of knee arthropathy and lumbar osteopenia.

Phenotypic and genotypic analysis of enterotoxigenic Escherichia coli in samples obtained from Egyptian children presenting to referral hospitals.

Hospital surveillance was established in the Nile River Delta to increase the understanding of the epidemiology of diarrheal disease among Egyptian children. Between September 2000 and August 2003, samples obtained from children less than 5 years of age who had diarrhea and who were seeking hospital care were cultured for enteric bacteria. Colonies from each culture with a morphology typical of that of Escherichia coli were tested for the heat-labile (LT) and heat-stable (ST) toxins by a GM-1-specific enzyme-linked immunosorbent assay and colonization factor (CF) antigens by an immunodot blot assay. Enterotoxigenic E. coli (ETEC) isolates were recovered from 320/1,540 (20.7%) children, and ETEC isolates expressing a known CF were identified in 151/320 (47%) samples. ST CFA/I, ST CS6, ST CS14, and LT and ST CS5 plus CS6 represented 75% of the CFs expressed by ETEC isolates expressing a detectable CF. Year-to-year variability in the proportion of ETEC isolates that expressed a detectable CF was observed (e.g., the proportion that expressed CFA/I ranged from 10% in year 1 to 21% in year 3); however, the relative proportions of ETEC isolates expressing a CF were similar over the reporting period. The proportion of CF-positive ETEC isolates was higher among isolates that expressed ST. ETEC isolates expressing CS6 were isolated significantly less often (P < 0.001) than isolates expressing CFA/I in children less than 1 year of age. Macrorestriction profiling of CFA/I-expressing ETEC isolates by using the restriction enzyme XbaI and pulsed-field gel electrophoresis demonstrated a wide genetic diversity among the isolates that did not directly correlate with the virulence of the pathogen. The genome plasticity demonstrated in the ETEC isolates collected in this work suggests an additional challenge to the development of a globally effective vaccine for ETEC.

Pathogenicity and convalescent excretion of Campylobacter in rural Egyptian children.

Campylobacter infection in developing countries has not received much public health attention because of the observation that infections are not associated with disease beyond the first 6 months of life. A cohort of 397 Egyptian children aged less than 3 years, who were observed twice weekly during 1995--1998, experienced an incidence of 0.6 episodes of Campylobacter diarrhea per child-year. A total of 13% of the Campylobacter diarrheal episodes were characterized by severe dehydration. Age-specific incidence rates (episodes per year) were 0.9 in infants aged less than 6 months, 1.5 in those 6--12 months, and 0.4 and 0.2 in the second and third years of life, respectively. Convalescent excretion of Campylobacter after a diarrheal episode might be enhancing transmission and contributing to this high incidence. Observed risk factors for Campylobacter diarrhea were poor hygienic conditions and the presence of animals in the house. Regardless of the child's age, a first infection by Campylobacter was associated with diarrhea (odds ratio = 2.45; 95% confidence interval: 1.61, 3.71); however, subsequent infections were associated with diarrhea only in children aged less than 6 months. This observation that natural infection did not confer protection during the first 6 months of life poses a challenge to vaccine development.