8 results on '"Adetifa, Ifedayo"'
Search Results
2. Population immunity to pneumococcal serotypes in Kilifi, Kenya, before and 6 years after the introduction of PCV10 with a catch-up campaign: an observational study of cross-sectional serosurveys.
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Gallagher, Katherine E, Adetifa, Ifedayo M O, Mburu, Caroline, Bottomley, Christian, Akech, Donald, Karani, Angela, Pearce, Emma, Wang, Yanyun, Kagucia, E Wangeci, Goldblatt, David, Hammitt, Laura L, and Scott, J Anthony G
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HERD immunity , *IMMUNOLOGIC memory , *SEROTYPES , *SCIENTIFIC observation , *CROSS-sectional method - Abstract
In Kilifi (Kenya), a pneumococcal conjugate vaccine (PCV10) was introduced in 2011 in infants (aged <1 year, 3 + 0 schedule) with a catch-up campaign in children aged 1–4 years. We aimed to measure the effect of PCV10 on population immunity. In this observational study, repeated cross-sectional serosurveys were conducted in independent random samples of 500 children younger than 15 years every 2 years between 2009 and 2017. During these surveys, blood samples were collected by venesection. Concentrations of anti-capsular IgGs against vaccine serotypes (VTs) 1, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F, and against serotypes 6A and 19A, were assayed by ELISA. We plotted the geometric mean concentrations (GMCs) by birth year to visualise age-specific antibody profiles. In infants, IgG concentrations of 0·35 μg/mL or higher were considered protective. Of 3673 volunteers approached, 2152 submitted samples for analysis across the five surveys. Vaccine introduction resulted in an increase in the proportion of young children with protective IgG concentrations, compared with before vaccine introduction (from 0–33% of infants with VT-specific levels over the correlate of protection in 2009, to 60–94% of infants in 2011). However, among those vaccinated in infancy, GMCs of all ten VTs had waned rapidly by the age of 1, but rose again later in childhood. GMCs among children aged 10–14 years were consistently high over time (eg, the range of GMCs across survey rounds were between 0·45 μg/mL and 1·00 μg/mL for VT 23F and between 2·00 μg/mL and 3·11 μg/mL for VT 19F). PCV10 in a 3 + 0 schedule elicited protective IgG levels during infancy, when disease risk is high. The high antibody levels in children aged 10–14 years might indicate continued exposure to vaccine serotypes due to residual carriage or to memory responses to cross-reactive antigens. Despite rapid waning of IgG after vaccination, disease incidence among young children in this setting remains low, suggesting that lower thresholds of antibody, or other markers of immunity (eg, memory B cells), may be needed to assess population protection among children who have aged past infancy. Gavi, the Vaccine Alliance; Wellcome Trust. [ABSTRACT FROM AUTHOR]
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- 2023
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3. WHO preferred product characteristics for monoclonal antibodies for passive immunization against respiratory syncytial virus (RSV) disease in infants – Key considerations for global use.
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Sparrow, Erin, Adetifa, Ifedayo, Chaiyakunapruk, Nathorn, Cherian, Thomas, Fell, Deshayne B., Graham, Barney S., Innis, Bruce, Kaslow, David C., Karron, Ruth A., Nair, Harish, Neuzil, Kathleen M., Saha, Samir, Smith, Peter G., Srikantiah, Padmini, Were, Fred, Zar, Heather J., and Feikin, Daniel
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RESPIRATORY syncytial virus , *PRODUCT attributes , *MONOCLONAL antibodies , *INFANT diseases , *IMMUNIZATION , *MIDDLE-income countries - Abstract
World Health Organization (WHO) preferred product characteristics describe preferences for product attributes that would help optimize value and use to address global public health needs, with a particular focus on low- and middle-income countries. Having previously published preferred product characteristics for both maternal and paediatric respiratory syncytial virus (RSV) vaccines, WHO recently published preferred product characteristics for monoclonal antibodies to prevent severe RSV disease in infants. This article summarizes the key attributes from the preferred product characteristics and discusses key considerations for future access and use of preventive RSV monoclonal antibodies. [ABSTRACT FROM AUTHOR]
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- 2022
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4. Upper airways colonisation of Streptococcus pneumoniae in adults aged 60 years and older: A systematic review of prevalence and individual participant data meta-analysis of risk factors.
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Smith, Emma L., Wheeler, India, Adler, Hugh, Ferreira, Daniela M., Sá-Leão, Raquel, Abdullahi, Osman, Adetifa, Ifedayo, Becker-Dreps, Sylvia, Esposito, Susanna, Farida, Helmia, Kandasamy, Rama, Mackenzie, Grant A., Nuorti, J. Pekka, Nzenze, Susan, Madhi, Shabir A., Ortega, Omar, Roca, Anna, Safari, Dodi, Schaumburg, Frieder, and Usuf, Effua
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STREPTOCOCCAL disease prevention ,RESEARCH ,META-analysis ,RESEARCH methodology ,SYSTEMATIC reviews ,STREPTOCOCCAL diseases ,PNEUMOCOCCAL vaccines ,MEDICAL cooperation ,EVALUATION research ,STREPTOCOCCUS ,NASOPHARYNX ,COMPARATIVE studies ,DISEASE prevalence ,CARRIER state (Communicable diseases) - Abstract
Background: Colonisation with Streptococcus pneumoniae can lead to invasive pneumococcal disease and pneumonia. Pneumococcal acquisition and prevalence of colonisation are high in children. In older adults, a population susceptible to pneumococcal disease, colonisation prevalence is reported to be lower, but studies are heterogeneous.Methods: This is a systematic review and meta-analysis of prevalence of, and risk factors for, pneumococcal colonisation in adults ≥ 60 years of age (PROSPERO #42016036891). We identified peer-reviewed studies reporting the prevalence of S. pneumoniae colonisation using MEDLINE and EMBASE (until April 2016), excluding studies of acute disease. Participant-level data on risk factors were sought from each study.Findings: Of 2202 studies screened, 29 were analysable: 18 provided participant-level data (representing 6290 participants). Prevalence of detected pneumococcal colonisation was 0-39% by conventional culture methods and 3-23% by molecular methods. In a multivariate analysis, colonisation was higher in persons from nursing facilities compared with the community (odds ratio (OR) 2•30, 95% CI 1•26-4•21 and OR 7•72, 95% CI 1•15-51•85, respectively), in those who were currently smoking (OR 1•69, 95% CI 1•12-2•53) or those who had regular contact with children (OR 1•93, 95%CI 1•27-2•93). Persons living in urban areas had significantly lower carriage prevalence (OR 0•43, 95%CI 0•27-0•70).Interpretation: Overall prevalence of pneumococcal colonisation in older adults was higher than expected but varied by risk factors. Future studies should further explore risk factors for colonisation, to highlight targets for focussed intervention such as pneumococcal vaccination of high-risk groups.Funding: No funding was required. [ABSTRACT FROM AUTHOR]- Published
- 2020
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5. Coverage and timeliness of vaccination and the validity of routine estimates: Insights from a vaccine registry in Kenya.
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Adetifa, Ifedayo M.O., Karia, Boniface, Mutuku, Alex, Bwanaali, Tahreni, Makumi, Anne, Wafula, Jackline, Chome, Martina, Mwatsuma, Pauline, Bauni, Evasius, Hammitt, Laura L., Mataza, Christine, Tabu, Collins, Kamau, Tatu, Williams, Thomas N., and Scott, J. Anthony G.
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VACCINATION , *PNEUMOCOCCAL vaccines , *MEDICATION errors , *MEASLES vaccines , *IMMUNITY - Abstract
Highlights • A high coverage is essential if the full benefits of vaccines are to be enjoyed. • A vaccine registry can help quantify the errors in coverage estimates from surveys. • Vaccination coverage obtained using a survey approach overestimates coverage by 2%. • Survey and administrative methods underestimate fully immunised children by ≥10%. • Non-hospital delivery and stock-outs were associated with failure to vaccinate. Abstract Background The benefits of childhood vaccines are critically dependent on vaccination coverage. We used a vaccine registry (as gold standard) in Kenya to quantify errors in routine coverage methods (surveys and administrative reports), to estimate the magnitude of survivor bias, contrast coverage with timeliness and use both measures to estimate population immunity. Methods Vaccination records of children in the Kilifi Health and Demographic Surveillance System (KHDSS), Kenya were combined with births, deaths, migration and residence data from 2010 to 17. Using inverse survival curves, we estimated up-to-date and age-appropriate vaccination coverage, calculated mean vaccination coverage in infancy as the area under the inverse survival curves, and estimated the proportion of fully immunised children (FIC). Results were compared with published coverage estimates. Risk factors for vaccination were assessed using Cox regression models. Results We analysed data for 49,090 infants and 48,025 children aged 12–23 months in 6 birth cohorts and 6 cross-sectional surveys respectively, and found 2nd year of life surveys overestimated coverage by 2% compared to birth cohorts. Compared to mean coverage in infants, static coverage at 12 months was exaggerated by 7–8% for third doses of oral polio, pentavalent (Penta3) and pneumococcal conjugate vaccines, and by 24% for the measles vaccine. Surveys and administrative coverage also underestimated the proportion of the fully immunised child by 10–14%. For BCG, Penta3 and measles, timeliness was 23–44% higher in children born in a health facility but 20–37% lower in those who first attended during vaccine stock outs. Conclusions Standard coverage surveys in 12–23 month old children overestimate protection by ignoring timeliness, and survivor and recall biases. Where delayed vaccination is common, up-to-date coverage will give biased estimates of population immunity. Surveys and administrative methods also underestimate FIC prevalence. Better measurement of coverage and more sophisticated analyses are required to control vaccine preventable diseases. [ABSTRACT FROM AUTHOR]
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- 2018
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6. High granulocyte/lymphocyte ratio and paucity of NKT cells defines TB disease in a TB-endemic setting.
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Sutherland, Jayne S., Jeffries, David J., Donkor, Simon, Walther, Brigitte, Hill, Philip C., Adetifa, Ifedayo M.O., Adegbola, Richard A., and Ota, Martin O.C.
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TUBERCULOSIS diagnosis ,GRANULOCYTE antigens ,IMMUNE response ,BACTERIAL growth ,FLOW cytometry ,PUBLIC health ,T cells ,MYCOBACTERIUM tuberculosis - Abstract
Summary: Most people infected with Mycobacterium tuberculosis, the causative agent of tuberculosis (TB) actually maintain a strong immune response and are able to control bacterial growth (deemed latently infected (LTBI)), while approximately 10% progress to disease resulting in almost 2 million deaths per year. Determining the immune ‘footprint’ at specific stages of infection and disease will allow for better diagnostics, treatments and ultimately development of new vaccine candidates. In this study we performed multi-factorial flow cytometry on fresh blood from 56 TB cases, 46 Tuberculin Skin Test (TST) positive (LTBI) and 39 TST negative household contacts. We found a highly significant increase in granulocytes and decrease in B cells and invariant (Vα24+Vβ11+) NKT cells in TB cases compared to TST+ contacts (p <0.0001, p =0.007 and p =0.01 respectively) which were restored to LTBI levels following 6 months of TB treatment. Using support vector analysis, we found a combination of granulocyte and lymphocyte and/or NKT cell proportions allowed almost 90% correct classification into M. tuberculosis infection or disease. This work has important public health benefits in regards to diagnosis and treatment of TB in sub-Saharan Africa and in furthering our understanding of the requirements for protective immunity to TB. [Copyright &y& Elsevier]
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- 2009
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7. Sustained reduction in vaccine-type invasive pneumococcal disease despite waning effects of a catch-up campaign in Kilifi, Kenya: A mathematical model based on pre-vaccination data.
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Ojal, John, Flasche, Stefan, Hammitt, Laura L., Akech, Donald, Kiti, Moses C., Kamau, Tatu, Adetifa, Ifedayo, Nurhonen, Markku, Scott, J. Anthony G., and Auranen, Kari
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NASOPHARYNX diseases , *PNEUMOCOCCAL vaccines , *MATHEMATICAL models - Abstract
Background In 2011, Kenya introduced the 10-valent pneumococcal conjugate vaccine together with a catch-up campaign for children aged <5 years in Kilifi County. In a post-vaccination surveillance study based in Kilifi, there was a substantial decline in invasive pneumococcal disease (IPD). However, given the continued circulation of the vaccine serotypes it is possible that vaccine-serotype disease may re-emerge once the effects of the catch-up campaign wear off. Methods We developed a compartmental, age-structured dynamic model of pneumococcal carriage and invasive disease for three serotype groups: the 10-valent vaccine serotypes and two groups of non-vaccine serotypes based on their susceptibility to mutual competition. The model was calibrated to age- and serotype-specific data on carriage and IPD in the pre-vaccination era and used to predict carriage prevalence and IPD up to ten years post-vaccination in Kilifi. The model was validated against the observed carriage prevalence after vaccine introduction. Results The model predicts a sustained reduction in vaccine-type pneumococcal carriage prevalence from 33% to 8% in infants and from 30% to 8% in 1–5 year olds over the 10-year period following vaccine introduction. The incidence of IPD is predicted to decline across all age groups resulting in an overall reduction of 56% in the population, corresponding to 10.4 cases per 100,000 per year. The vaccine-type IPD incidence is estimated to decline by 83% while non-vaccine-type IPD incidence is predicted to increase by 52%. The model's predictions of carriage prevalence agrees well with the observed data in the first five years post-vaccination. Conclusion We predict a sustained and substantial decline in IPD through PCV vaccination and that the current regimen is insufficient to fully eliminate vaccine-serotype circulation in the model. We show that the observed impact is likely to be sustained despite waning effects of the catch-up campaign. [ABSTRACT FROM AUTHOR]
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- 2017
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8. Drug-resistant tuberculosis: time for visionary political leadership.
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Abubakar, Ibrahim, Zignol, Matteo, Falzon, Dennis, Raviglione, Mario, Ditiu, Lucica, Masham, Susan, Adetifa, Ifedayo, Ford, Nathan, Cox, Helen, Lawn, Stephen D, Marais, Ben J, McHugh, Timothy D, Mwaba, Peter, Bates, Matthew, Lipman, Marc, Zijenah, Lynn, Logan, Simon, McNerney, Ruth, Zumla, Adam, and Sarda, Krishna
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TUBERCULOSIS treatment , *DRUG resistance , *POLITICAL leadership , *COST effectiveness , *MEDICAL care costs , *DISEASE prevalence - Abstract
Summary: Two decades ago, WHO declared tuberculosis a global emergency, and invested in the highly cost-effective directly observed treatment short-course programme to control the epidemic. At that time, most strains of Mycobacterium tuberculosis were susceptible to first-line tuberculosis drugs, and drug resistance was not a major issue. However, in 2013, tuberculosis remains a major public health concern worldwide, with prevalence of multidrug-resistant (MDR) tuberculosis rising. WHO estimates roughly 630 000 cases of MDR tuberculosis worldwide, with great variation in the frequency of MDR tuberculosis between countries. In the past 8 years, extensively drug-resistant (XDR) tuberculosis has emerged, and has been reported in 84 countries, heralding the possibility of virtually untreatable tuberculosis. Increased population movement, the continuing HIV pandemic, and the rise in MDR tuberculosis pose formidable challenges to the global control of tuberculosis. We provide an overview of the global burden of drug-resistant disease; discuss the social, health service, management, and control issues that fuel and sustain the epidemic; and suggest specific recommendations for important next steps. Visionary political leadership is needed to curb the rise of MDR and XDR tuberculosis worldwide, through sustained funding and the implementation of global and regional action plans. [ABSTRACT FROM AUTHOR]
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- 2013
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