Modelling transmission, immunity and disease of <i>Haemophilus influenzae</i> type b in a structured population

Auranen, Kari; Eichner, Martin; Leino, Tuija; Takala, Aino K.; Mäkelä, P. Helena; Takala, Tapio

doi:10.1017/s0950268804002493

Cited by 18 publications

(22 citation statements)

References 31 publications

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“…The demographic model has been described in detail elsewhere [28] (see also Table S1.1 in File S1). Briefly, it is an individual-based contact network (microsimulation) model that mimics the population turnover of the population in a developed country (Finland).…”

Section: Methodsmentioning

confidence: 99%

Pneumococcal Transmission and Disease In Silico: A Microsimulation Model of the Indirect Effects of Vaccination

2013

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BackgroundThe degree and time frame of indirect effects of vaccination (serotype replacement and herd immunity) are key determinants in assessing the net effectiveness of vaccination with pneumococcal conjugate vaccines (PCV) in control of pneumococcal disease. Using modelling, we aimed to quantify these effects and their dependence on coverage of vaccination and the vaccine's efficacy against susceptibility to pneumococcal carriage.Methods and FindingsWe constructed an individual-based simulation model that explores the effects of large-scale PCV programmes and applied it in a developed country setting (Finland). A population structure with transmission of carriage taking place within relevant mixing groups (families, day care groups, schools and neighbourhoods) was considered in order to properly assess the dependency of herd immunity on coverage of vaccination and vaccine efficacy against carriage. Issues regarding potential serotype replacement were addressed by employing a novel competition structure between multiple pneumococcal serotypes. Model parameters were calibrated from pre-vaccination data about the age-specific carriage prevalence and serotype distribution. The model predicts that elimination of vaccine-type carriage and disease among those vaccinated and, due to a substantial herd effect, also among the general population takes place within 5–10 years since the onset of a PCV programme with high (90%) coverage of vaccination and moderate (50%) vaccine efficacy against acquisition of carriage. A near-complete replacement of vaccine-type carriage by non-vaccine-type carriage occurs within the same time frame.ConclusionsThe changed patterns in pneumococcal carriage after PCV vaccination predicted by the model are unequivocal. The overall effect on disease incidence depends crucially on the magnitude of age- and serotype-specific case-to-carrier ratios of the remaining serotypes relative to those of the vaccine types. Thus the availability of reliable data on the incidence of both pneumococcal carriage and disease is essential in assessing the net effectiveness of PCV vaccination in a given epidemiological setting.

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Section: Methodsmentioning

confidence: 99%

Pneumococcal Transmission and Disease In Silico: A Microsimulation Model of the Indirect Effects of Vaccination

2013

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“…21,22 The exacerbated response to primary immunization in Venezuelan children suggests priming by natural exposure at a higher magnitude, probably because of high colonization indices, maintaining circulation of the microorganism. 12 In the Dominican Republic vaccination with the full-dose regimen elicited concentrations above 13 mg/mL, whereas fractional doses induced even higher antibody concentrations. 18 Children from the USA and Europe reached antibody anti-PRP-T concentrations of 3.6-6.4 mg/mL.…”

Section: Discussionmentioning

confidence: 98%

“…If the aforementioned is not achieved and a booster dose is not given, residual cases of Hib disease may emerge among unvaccinated individuals. 12,13 Differences in the epidemiology and immunology of Hib in different locations have implications for the success of vaccination. [14][15][16] The more accepted schedule consists of three doses given at two, four and six months of age, and an additional booster dose in the second year of life.…”

Section: Introductionmentioning

confidence: 99%

Anticapsular Polysaccharide IgG Concentrations in Mexican Children Formerly Immunized with Haemophilus Influenzae b Prp-T Vaccine

León¹,

García²,

Arredondo³

et al. 2007

Human Vaccines

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Background: In 1999 H. influenzae b (Hib) PRP-T vaccine was introduced into primary immunization schedule in Mexico. There have been no studies evaluating antibody response after widespread immunization in our country. It is now recognized that Hib conjugates induce significant initial antibody levels that in some cases wane over time. This study relies on the measurement of IgG serum antibody concentrations to Hib capsular polysaccharide (PS) and is interpreted in the light of the accepted levels ≥0.15 mg/mL for short-term protection against Hib invasive disease and ≥5.0 mg/mL for protection against Hib oropharyngeal carriage.Methods: Using a validated ELISA assay, we measured the IgG serum antibody concentrations in 115 children between 7 and 93 months of age who had received three doses of PRP-T. We used the standard reference serum US FDA 1983 for quantification of PS antibody levels. Concentrations were estimated using 3 rd degree polynomial regression lines. As there was no unvaccinated group available (>95% of Mexican children have received the Hib vaccine), the study was designed as a cross-sectional.Results: All children had serum IgG concentrations ≥0.15 mg/mL [range 0.24-54.64 mg/mL]; 69.6 % (80/115) had ≥1.0 mg/mL and 14% (16/115) showed concentrations ≥5.0 mg/mL. The vaccine elicited geometric mean concentrations (GMC) of 4.0, 1.6, 1.4 and 2.4 mg/mL in groups of 7-12, 13-24, 25-48 and 49-93 month-old respectively.Conclusions: PRP-T vaccination in this group of Mexican children has resulted in serum IgG concentrations ≥0.15 mg/mL, suggesting that Hib immunization has conferred protection against invasive disease.

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“…The increasing IgG concentration after the fourth year of age could be related to the maximum carriage rates of Hib (4,6).…”

mentioning

confidence: 99%

“…The differing GMCs between children from Mexico City and those from Guadalajara could be attributed to differences in natural boosting, given the discrepancy in the average age of the two study populations (4,17,19). Besides, the immunoepidemiologies of Hib can differ among the subpopulations of a country (10).…”

mentioning

confidence: 99%

Immunoglobulin G Avidities in Infants in Mexico after Primary Immunization with Three Doses of Polyribosylribitol Phosphate-Tetanus ToxoidHaemophilus influenzaeType b Vaccine

Gómez-de-León

Díaz-García

Villaseñor-Sierra

et al. 2008

Clin Vaccine Immunol

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Serum immunoglobulin G concentrations and avidities specific to Haemophilus influenzae type b (Hib) were measured in 208 children living in Guadalajara and Mexico City. Protective concentrations were found in 98.9% and 100.0% of participants, respectively. Geometric mean concentrations differed between both populations and/or among age groups. Mean avidities differed only among the 7-to 12-month-old children. Diphtheria-tetanus-whole-cell pertussis-hepatitis B-Hib primary vaccination seems to induce protection in Mexican children.

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Modelling transmission, immunity and disease of Haemophilus influenzae type b in a structured population

Cited by 18 publications

References 31 publications

Pneumococcal Transmission and Disease In Silico: A Microsimulation Model of the Indirect Effects of Vaccination

Pneumococcal Transmission and Disease In Silico: A Microsimulation Model of the Indirect Effects of Vaccination

Anticapsular Polysaccharide IgG Concentrations in Mexican Children Formerly Immunized with Haemophilus Influenzae b Prp-T Vaccine

Immunoglobulin G Avidities in Infants in Mexico after Primary Immunization with Three Doses of Polyribosylribitol Phosphate-Tetanus ToxoidHaemophilus influenzaeType b Vaccine

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