Regional and age-specific patterns of pandemic H1N1 influenza virus seroprevalence inferred from vaccine clinical trials, August-October 2009.

The extent of the H1N1 pandemic has been estimated from case counts and deaths but the proportion of exposed populations with inapparent infections has not been described in detail. We analysed haemagglutination-inhibition (HI) antibody titres of pre-vaccination sera from pandemic vaccine trials conducted in six countries on four continents to provide an indication of A/CA/07/2009(H1N1)-like influenza seroprevalence in those populations. Among 7,962 subjects, ranging in age from 12 months to over 60 years, the proportions with HI antibody titres > or =40 to the H1N1pnd virus in the period from August to October 2009 were, by country: Costa Rica 26.4%, United States (US) 22.5%, Switzerland 16.9%, Germany 12.6%, Belgium 10.1%, and Japan 5.9%. Age-specific seropositivity rates in the samples were higher in children and adolescents in Costa Rica and in the US than in Europe and in Japan. The low proportion of seropositive children in Europe and Japan suggests that little local viral transmission had occurred in those regions even as late as September and October 2009, while in the US and Costa Rica, the greater proportion of previously infected children and young adults suggested that a significant number of asymptomatic infections had occurred during the first pandemic wave. Nevertheless, in all locations, the majority of the population remained susceptible to the pandemic virus at the beginning of the influenza season in the northern hemisphere, justifying the implementation of public health interventions.

Children with Haemophilus influenzae bacteremia initially treated as outpatients: outcome in 85 American Indian children.

Eighty-five American Indian children less than 16 years of age with Haemophilus influenzae bacteremia were retrospectively determined to have been treated as outpatients after their initial evaluation. We hoped to determine the proportion that developed new foci, the time interval to this development and whether age or temperature at presentation predicted outcome. Fifty-one (60%) presented with nonfocal findings. Seventy-two (85%) were treated with antibiotics at the initial visit. Although 49 (58%) of the patients were never hospitalized, a new focus was identified in 25 (29%), including 13 (15%) with a final diagnosis of meningitis. The new foci were identified within 6 days of presentation (median, 2 days). An additional 15 (18%) patients had no new focus but were febrile and/or ill at follow-up. All patients with meningitis or a second positive culture were hospitalized at the first follow-up visit. Age and temperature at presentation did not help predict outcome. All patients with H. influenzae bacteremia require prompt reevaluation and close follow-up by an experienced physician.

Persistent urinary antigen excretion in infants vaccinated with Haemophilus influenzae type b capsular polysaccharide conjugated with outer membrane protein from Neisseria meningitidis.

Testing for urinary excretion of capsular polysaccharide antigen was carried out in 40 four-month-old Navajo infants who had received injections of a Haemophilus influenzae type b Neisseria meningitidis outer membrane protein conjugate vaccine (PedvaxHIB; Merck, Sharp and Dohme Research Laboratories) as part of an ongoing efficacy trial of the vaccine. Urine from 12 placebo recipients was also analyzed. Urine samples were collected on the day of injection (the first voided urine following the injection) and 3, 7, 10, 14, 21 and 30 days later. All vaccine recipients had at least 1 positive specimen. Vaccine recipients excreted antigen for a median period of 14 days after injection. On the first day 54% of vaccinees excreted antigen. Antigen was excreted by 89% of vaccinees on Day 3, 79% on Day 7, 82% on Day 10, 64% on Day 14, 56% on Day 21 and 41% on Day 30. Urine from placebo recipients tested positive in 12% on Day 1, 18% on Day 3, none on Day 7, 14% on Day 10, 11% on Day 14, 10% on Day 21 and none on Day 30. The rate of positive test results was significantly higher among vaccine recipients than among controls. Physicians should not rely on urinary antigen detection tests for predicting the presence of invasive disease caused by H. influenzae type b in infants for at least 30 days after injections with this conjugate vaccine, and possibly longer.

The efficacy in Navajo infants of a conjugate vaccine consisting of Haemophilus influenzae type b polysaccharide and Neisseria meningitidis outer-membrane protein complex.

BACKGROUND AND METHODS: Several conjugate vaccines against Haemophilus influenzae type b have been developed in the search for one that induces protection even in young infants. We evaluated the safety and efficacy of a conjugate vaccine that links the H. influenzae type b capsular polysaccharide to the outer-membrane protein complex (OMPC) of Neisseria meningitidis serogroup B. We conducted a double-blind, placebo, controlled trial in Navajo infants, who are at high risk for systemic infections caused by H. influenzae type b. The infants were randomly assigned to receive the first dose of vaccine or placebo at 42 to 90 days of age and the second at 70 to 146 days of age. RESULTS: Of the infants in the trial, 2588 were assigned to receive the vaccine and 2602 to receive placebo. The mean follow-up was 269 days in the vaccine group and 267 days in the placebo group. Before the age of 18 months, there was 1 systemic H. influenzae type b infection in the vaccine group, as compared with 22 in the placebo group (P less than 0.001; point estimate of efficacy, 95 percent; 95 percent confidence interval, 72 to 99 percent). Of the 22 H. influenzae type b infections in the placebo group, 13 were meningitis. Among the children who received both doses, there was 1 H. influenzae type b infection in the vaccine group (n = 2056) and 14 in the placebo group (n = 2105) (P less than 0.001; point estimate of efficacy, 93 percent; 95 percent confidence interval, 53 to 98 percent). The single infection in the vaccine group occurred at 15 1/2 months of age in an infant with osteomyelitis. Between the first and second doses there were no H. influenzae type b infections in the vaccine group and eight in the placebo group (P less than 0.005; point estimate of efficacy, 100 percent; 95 percent confidence interval, 41 to 100 percent). CONCLUSIONS: The H. influenzae type b OMPC vaccine, administered at 2 and 4 months of age, is safe and induces a high rate of protection against invasive disease caused by H. influenzae type b in infants under the age of 18 months. Protection begins after the first dose.

Identification and localization of glucagon-related peptides in rat brain.

Immunochemical and immunocytochemical techniques have been used to identify and characterize glucagon-related peptides of the rat central nervous system. These peptides show immunoreactivity with antiglucagon sera directed towards the central portion of the hormone, but not with antisera specific for the free COOH terminus of glucagon. Highest concentrations were found in hypothalamus (6.1 +/- 1.6 ng/g wet weight) although lower amounts (approximately 2 ng/g) were found in cortex, thalamus, cerebellum, and brain stem. Gel filtration of brain extracts revealed at least two immunoreactive forms, which have molecular weights of about 12,000 and 8000. Both peptides had radioimmunoassay dilution curves parallel to the curve for glucagon and both had identical counterparts in extracts of rat intestine. Digestion of the brain and intestinal peptides with trypsin plus carboxypeptidase B released the immunoreactive COOH-terminal tryptic fragment of pancreatic glucagon from these larger forms. Immunocytochemical studies using antiglucagon serum and peroxidase-antiperoxidase staining identified glucagon-like material in neuronal cell bodie and processes in the magnocellular portion of the paraventricular nucleus, as well as in scattered cells in the supraoptic nucleus and in fibers in the median eminence. These results suggest that glucagon-containing peptides that have undergone the intestinal type of posttranslational modification are present in neuronal cells of the rat hypothalamus.

High titer glucagon antisera.

Antibody titers in rabbits immunized with glucagon conjugated to albumin using difluorodinitrobenzene rose rapidly. Under conditions of immunoassay, less than 2 nl of serum from two of four animals and approximately 4 nl from the other two was required to bind 50% of the 10 pg of [125I]iodoglucagon 100 days after immunization. The dissociation constants of the two higher titer antisera for glucagon were approximately 1 x 10(-10)M, and their binding capacities for the hormone, about 50 mug/ml. Competitive binding assays showed that neither of these antisera cross-reacts with the glucagon-like, immunoreactive peptides extracted from intestine to greater than 2.5%. In contrast, hens produced antisera which were reactive with the intestinal material and which bound only 0.3 mug of glucagon per ml. There were no consistent differences, however, in the abilities of specific and non-specific antisera to react with selected fragments of pancreatic glucagon.