Browsing by Author "Phiri B"

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Attrition from HIV treatment after enrollment in a differentiated service delivery model: A cohort analysis of routine care in Zambia.
(2023) Jo Y; Jamieson L; Phiri B; Grimsrud A; Mwansa M; Shakwelele H; Haimbe P; Mukumbwa-Mwenechanya M; Mulenga PL; Nichols BE; Rosen S; Department of Internal Medicine, Health Economics and Epidemiology Research Office, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.; Department of Medicine, Section of Infectious Diseases, Boston Medical Center, Boston, MA, United States of America.; Clinton Health Access Initiative, Lusaka, Zambia.; Department of Medical Microbiology, Amsterdam University Medical Center, Amsterdam, Netherlands.; HIV Programmes and Advocacy, International AIDS Society, Cape Town, South Africa.; Ministry of Health, Lusaka, Zambia.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; Department of Global Health, Boston University School of Public Health, Boston, MA, United States of America.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
BACKGROUND: Many sub-Saharan Africa countries are scaling up differentiated service delivery (DSD) models for HIV treatment to increase access and remove barriers to care. We assessed factors associated with attrition after DSD model enrollment in Zambia, focusing on patient-level characteristics. METHODS: We conducted a retrospective record review using electronic medical records (EMR) of adults (≥15 years) initiated on antiretroviral (ART) between 01 January 2018 and 30 November 2021. Attrition was defined as lost to follow-up (LTFU) or died by November 30, 2021. We categorized DSD models into eight groups: fast-track, adherence groups, community pick-up points, home ART delivery, extended facility hours, facility multi-month dispensing (MMD, 4-6-month ART dispensing), frequent refill care (facility 1-2 month dispensing), and conventional care (facility 3 month dispensing, reference group). We used Fine and Gray competing risk regression to assess patient-level factors associated with attrition, stratified by sex and rural/urban setting. RESULTS: Of 547,281 eligible patients, 68% (n = 372,409) enrolled in DSD models, most commonly facility MMD (n = 306,430, 82%), frequent refill care (n = 47,142, 13%), and fast track (n = 14,433, 4%), with <2% enrolled in the other DSD groups. Retention was higher in nearly all DSD models for all dispensing intervals, compared to the reference group, except fast track for the ≤2 month dispensing group. Retention benefits were greatest for patients in the extended clinic hours group and least for fast track dispensing. CONCLUSION: Although retention in HIV treatment differed by DSD type, dispensing interval, and patient characteristics, nearly all DSD models out-performed conventional care. Understanding the factors that influence the retention of patients in DSD models could provide an important step towards improving DSD implementation.
Changes in HIV treatment differentiated care uptake during the COVID-19 pandemic in Zambia: interrupted time series analysis.
(2021-Oct) Jo Y; Rosen S; Sy KTL; Phiri B; Huber AN; Mwansa M; Shakwelele H; Haimbe P; Mwenechanya MM; Lumano-Mulenga P; Nichols BE; Department of Global Health, Boston University School of Public Health, Boston, Massachusetts, USA.; Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.; Clinton Health Access Initiative, Lusaka, Zambia.; Department of Medical Microbiology, Amsterdam University Medical Centre, Amsterdam, The Netherlands.; Section of Infectious Diseases, Department of Medicine, Boston Medical Center, Boston, Massachusetts, USA.; Health Economics and Epidemiology Research Office, Department of Internal Medicine, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.; Ministry of Health, Lusaka, Zambia.; The Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
INTRODUCTION: Differentiated service delivery (DSD) models aim to improve the access of human immunodeficiency virus treatment on clients and reduce requirements for facility visits by extending dispensing intervals. With the advent of the COVID-19 pandemic, minimising client contact with healthcare facilities and other clients, while maintaining treatment continuity and avoiding loss to care, has become more urgent, resulting in efforts to increase DSD uptake. We assessed the extent to which DSD coverage and antiretroviral treatment (ART) dispensing intervals have changed during the COVID-19 pandemic in Zambia. METHODS: We used client data from Zambia's electronic medical record system (SmartCare) for 737 health facilities, representing about three-fourths of all ART clients nationally. We compared the numbers and proportional distributions of clients enrolled in DSD models in the 6 months before and 6 months after the first case of COVID-19 was diagnosed in Zambia in March 2020. Segmented linear regression was used to determine whether the outbreak of COVID-19 in Zambia further accelerated the increase in DSD scale-up. RESULTS AND DISCUSSION: Between September 2019 and August 2020, 181,317 clients aged 15 or older (81,520 and 99,797 from 1 September 2019 to 1 March 2020 and from 1 March to 31 August 2020, respectively) enrolled in DSD models in Zambia. Overall participation in all DSD models increased over the study period, but uptake varied by model. The rate of acceleration increased in the second period for home ART delivery (152%), CONCLUSIONS: Participation in DSD models for stable ART clients in Zambia increased after the advent of COVID-19, but dispensing intervals diminished. Eliminating obstacles to longer dispensing intervals, including those related to supply chain management, should be prioritized to achieve the expected benefits of DSD models and minimize COVID-19 risk.
Comparative analysis of cholera serum vibriocidal antibodies from Convalescent and vaccinated adults in Zambia.
(2024-Aug-13) Ng'ombe H; Bosomprah S; Phiri B; Muchimba M; Liswaniso F; Chibuye M; Luchen CC; Chibesa K; Musukuma-Chifulo K; Mwape K; Tigere S; Silwamba S; Sinkala A; Simuyandi M; Mbewe N; Kapaya F; Cunningham AF; Chilengi R; Sack D; Chisenga CC; Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia; Department of Biostatistics, School of Public Health, University of Ghana, Accra, Ghana. Electronic address: Samuel.Bosomprah@cidrz.org.; Zambia National Public Health Institute, Stand 1186, Corner of Chaholi & Addis Ababa Roads Rhodes Park, Lusaka, Zambia.; Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia.; Ministry of Health, Levy Mwanawasa University Teaching Hospital, Chainama, Off Great East, P.0 Box 310084, Lusaka, Zambia.; Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.; John Hopkins University, 615 N Wolfe St, Baltimore, United States of America.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
Cholera is responsible for 1.3 to 4.0 million cholera cases globally and poses a significant threat, with Zambia reporting 17,169 cases as of 4th February 2024. Recognizing the crucial link between natural cholera infections and vaccine protection, this study aimed to assess immune responses post cholera infection and vaccination. This was a comparative study consisting of 50 participants enrolled during a cholera outbreak in Zambia's Eastern Province and an additional 56 participants who received oral cholera vaccinations in Zambia's Central Province. Vibriocidal antibodies were plotted as geometric mean titres in the naturally infected and vaccinated individuals. A significant difference (p < 0.047) emerged when comparing naturally infected to fully vaccinated individuals (2 doses) on day 28 against V. cholerae Ogawa. Those who received two doses of the oral cholera vaccine had higher antibody titres than those who were naturally infected. Notably, the lowest titres occurred between 0-9 days post onset, contrasting with peak responses at 10-19 days. This study addresses a critical knowledge gap in understanding cholera immunity dynamics, emphasizing the potential superiority of vaccination-induced immune responses. We recommend post infection vaccination after 40 days for sustained immunity and prolonged protection, especially in cholera hotspots.
Diagnostic accuracy of saliva-based testing as a Vibrio cholerae surveillance tool among naturally infected patients.
(2025-Jan-21) Chisenga CC; Phiri B; Ng'ombe H; Muchimba M; Liswaniso F; Bernshtein B; Cunningham AF; Sack D; Bosomprah S; Department of Biostatistics, School of Public Health, University of Ghana, Accra, Ghana.; Enteric Disease and Vaccine Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham, UK.; Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.; Alter Lab, Ragon Institute of MGH, MIT and Harvard, Boston, USA.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
Saliva, as a diagnostic medium, offers a promising alternative to blood by virtue of its non-invasive collection, which enhances patient compliance, especially in paediatric and geriatric populations. In this study, we assessed the utility of saliva as a non-invasive medium for measuring Vibrio cholerae-specific serum antibodies in naturally infected individuals. We tested paired serum and saliva samples obtained from a total of 63 patients with cholera enrolled in a cohort study. Vibriocidal antibodies assay (IgM/IgG) as markers for accurate determination was used to determine cholera-specific antibody levels. Using receiver operating characteristics (ROC) curve, we found that the best cut-off that maximizes (sensitivity + specificity) is 10 titres. At this saliva titre, the sensitivity is 76.9% (95%CI: 60.9%, 87.7%) and specificity is 80.0% (95%CI: 56.6%, 92.5%). Using Spearman's correlation coefficient, we also found evidence of a positive correlation between V. cholerae saliva and serum antibodies (rho = 0.66, P < 0.001). In conclusion, saliva-based diagnostic cholera tests have high diagnostic accuracy and would be advantageous, cheaper, and quicker for early diagnosis of severe cholera outcomes.
How soon should patients be eligible for differentiated service delivery models for antiretroviral treatment? Evidence from a retrospective cohort study in Zambia.
(2022-Dec-22) Jamieson L; Rosen S; Phiri B; Grimsrud A; Mwansa M; Shakwelele H; Haimbe P; Mukumbwa-Mwenechanya M; Lumano-Mulenga P; Chiboma I; Nichols BE; Department of Global Health, Boston University School of Public Health, Boston, Massachusetts, USA.; Clinton Health Access Initiative, Lusaka, Zambia.; Health Economics and Epidemiology Research Office, University of the Witwatersrand Faculty of Health Sciences, Johannesburg, South Africa sbrosen@bu.edu.; Department of Medical Microbiology, Amsterdam University Medical Centre, Amsterdam, the Netherlands.; Implementation Science Unit, Center for Infectious Disease Research in Zambia, Lusaka, Zambia.; International AIDS Society, Cape Town, South Africa.; Ministry of Health, Lusaka, Zambia.; Health Economics and Epidemiology Research Office, University of the Witwatersrand Faculty of Health Sciences, Johannesburg, South Africa.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
OBJECTIVES: Patient attrition is high the first 6 months after antiretroviral therapy (ART) initiation. Patients with <6 months of ART are systematically excluded from most differentiated service delivery (DSD) models, which are intended to support retention. Despite DSD eligibility criteria requiring ≥6 months on ART, some patients enrol earlier. We compared loss to follow-up (LTFU) between patients enrolling in DSD models early with those enrolled according to guidelines, assessing whether the ART experience eligibility criterion is necessary. DESIGN: Retrospective cohort study using routinely collected electronic medical record data. SETTING: PARTICIPANTS: Adults (≥15 years) who initiated ART between 1 January 2019 and 31 December 2020. OUTCOMES: LTFU (>30 days late for scheduled visit) at 18 months for 'early enrollers' (DSD enrolment after <6 months on ART) and 'established enrollers' (DSD enrolment after ≥6 months on ART). We used a log-binomial model to compare LTFU risk, adjusting for age, sex, location, ART refill interval and DSD model. RESULTS: For 6340 early enrollers and 25 857 established enrollers, there were no differences in sex (61% female), age (median 37 years) or location (65% urban). ART refill intervals were longer for established versus early enrollers (72% vs 55% were given 4-6 months refills). LTFU at 18 months was 3% (192 of 6340) for early enrollers and 5% (24 646 of 25 857) for established enrollers. Early enrollers were 41% less likely to be LTFU than established patients (adjusted risk ratio 0.59, 95% CI 0.50 to 0.68). CONCLUSIONS: Patients enrolled in DSD after <6 months of ART were more likely to be retained than patients established on ART prior to DSD enrolment. A limitation is that early enrollers may have been selected for DSD due to providers' and patients' expectations about future retention. Offering DSD models to ART patients soon after ART initiation may help address high attrition during the early treatment period. TRIAL REGISTERATION NUMBER: NCT04158882.
Index and targeted community-based testing to optimize HIV case finding and ART linkage among men in Zambia.
(2020-Jun) Mwango LK; Stafford KA; Blanco NC; Lavoie MC; Mujansi M; Nyirongo N; Tembo K; Sakala H; Chipukuma J; Phiri B; Nzangwa C; Mwandila S; Nkwemu KC; Saadani A; Mwila A; Herce ME; Claassen CW; Maryland Global Initiatives Corporation Zambia, Lusaka, Zambia.; Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA.; Institute for Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC, USA.; Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA.; Centre for Infectious Disease Research in Zambia (CIDRZ), Lusaka, Zambia.; U.S. Center for Disease Control and Prevention, Lusaka, Zambia.; Center for International Health, Education, and Biosecurity, University of Maryland School of Medicine, Baltimore, MD, USA.
INTRODUCTION: Current healthcare systems fail to provide adequate HIV services to men. In Zambia, 25% of adult men living with HIV were unaware of their HIV status in 2018, and 12% of those who were unaware of their HIV statu were not receiving antiretroviral therapy (ART) due to pervasive barriers to HIV testing services (HTS) and linkage to ART. To identify men and key and priority populations living with HIV in Zambia, and link them to care and treatment, we implemented the Community Impact to Reach Key and Underserved Individuals for Treatment and Support (CIRKUITS) project. We present HTS and ART linkage results from the first year of CIRKUITS. METHODS: CIRKUITS aimed to reach beneficiaries by training, mentoring, and deploying community health workers to provide index testing services and targeted community HTS. Community leaders and workplace supervisors were engaged to enable workplace HTS for men. To evaluate the effects of these interventions, we collected age- and sex-disaggregated routinely collected programme data for the first 12 months of the project (October 2018 to September 2019) across 37 CIRKUITS-supported facilities in three provinces. We performed descriptive statistics and estimated index cascades for indicators of interest, and used Chi square tests to compare indicators by age, sex, and district strata. RESULTS: Over 12 months, CIRKUITS tested 38,255 persons for HIV, identifying 10,974 (29%) new people living with HIV, of whom 10,239 (93%) were linked to ART. Among men, CIRKUITS tested 18,336 clients and identified 4458 (24%) as HIV positive, linked 4132 (93%) to ART. Men who tested HIV negative were referred to preventative services. Of the men found HIV positive, and 13.0% were aged 15 to 24 years, 60.3% were aged 25 to 39, 20.9% were aged 40 to 49 and 5.8% were ≥50 years old. Index testing services identified 2186 (49%) of HIV-positive men, with a positivity yield of 40% and linkage of 88%. Targeted community testing modalities accounted for 2272 (51%) of HIV-positive men identified, with positivity yield of 17% and linkage of 97%. CONCLUSIONS: Index testing and targeted community-based HTS are effective strategies to identify men living with HIV in Zambia. Index testing results in higher yield, but lower linkage and fewer absolute men identified compared to targeted community-based HTS.
Maternal and Infant Histo-Blood Group Antigen (HBGA) Profiles and Their Influence on Oral Rotavirus Vaccine (Rotarix
(2023-Jul-31) Chauwa A; Bosomprah S; Laban NM; Phiri B; Chibuye M; Chilyabanyama ON; Munsaka S; Simuyandi M; Mwape I; Mubanga C; Chobe MC; Chisenga C; Chilengi R; Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.; Department of Global Health, Amsterdam Institute for Global Health and Development (AIGHD), Amsterdam University Medical Centers, University of Amsterdam, 1012 WP Amsterdam, The Netherlands.; Department of Biostatistics, School of Public Health, University of Ghana, Accra P.O. Box LG13, Ghana.; Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka P.O. Box 50110, Zambia.; Enteric Disease and Vaccine Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka P.O. Box 34681, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
Live-attenuated, oral rotavirus vaccines have significantly reduced rotavirus-associated diarrhoea morbidity and infant mortality. However, vaccine immunogenicity is diminished in low-income countries. We investigated whether maternal and infant intrinsic susceptibility to rotavirus infection via histo-blood group antigen (HBGA) profiles influenced rotavirus (ROTARIX
Prevalence of Diarrhoeagenic
(2023-Nov-17) Mwape K; Bosomprah S; Chibesa K; Silwamba S; Luchen CC; Sukwa N; Mubanga C; Phiri B; Chibuye M; Liswaniso F; Somwe P; Chilyabanyama O; Chisenga CC; Muyoyeta M; Simuyandi M; Barnard TG; Chilengi R; Division of Medical Microbiology, Department of Pathology, Stellenbosch University & National Health Laboratory Service, Tygerberg Hospital Francie van Zijl Drive, P.O. Box 241, Cape Town 8000, South Africa.; Department of Global Health, Amsterdam Institute for Global Health and Development (AIGHD), Amsterdam University Medical Centers, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.; Amsterdam Institute of Infection and Immunity, Amsterdam University Medical Centers, 1105 AZ Amsterdam, The Netherlands.; Department of Basic Medical Sciences, Michael Chilufya Sata School of Medicine, Copperbelt University, Ndola P.O. Box 71191, Zambia.; Department of Biostatistics, School of Public Health, University of Ghana, Accra P.O. Box LG13, Ghana.; Next Generation Sequencing Unit and Division of Virology, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa.; Enteric Disease and Vaccine Research Unit, Center for Infectious Disease Research in Zambia, Lusaka P.O. Box 34681, Zambia.; Water and Health Research Center, Faculty of Health Sciences, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, South Africa.; Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka P.O. Box 50110, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
Diarrhoea is a major contributor to childhood morbidity and mortality in developing countries, with diarrhoeagenic
Seroconversion and Kinetics of Vibriocidal Antibodies during the First 90 Days of Re-Vaccination with Oral Cholera Vaccine in an Endemic Population.
(2024-Apr-08) Chisenga CC; Phiri B; Ng'ombe H; Muchimba M; Musukuma-Chifulo K; Silwamba S; Laban NM; Luchen C; Liswaniso F; Chibesa K; Mubanga C; Mwape K; Simuyandi M; Cunningham AF; Sack D; Bosomprah S; Department of Biostatistics, School of Public Health, University of Ghana, Accra P.O. Box LG13, Ghana.; Enteric Disease and Vaccine Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka P.O. Box 34681, Zambia.; Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.; Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
Despite the successful introduction of oral cholera vaccines, Zambia continues to experience multiple, sporadic, and protracted cholera outbreaks in various parts of the country. While vaccines have been useful in staying the cholera outbreaks, the ideal window for re-vaccinating individuals resident in cholera hotspot areas remains unclear. Using a prospective cohort study design, 225 individuals were enrolled and re-vaccinated with two doses of Shanchol™, regardless of previous vaccination, and followed-up for 90 days. Bloods were collected at baseline before re-vaccination, at day 14 prior to second dosing, and subsequently on days 28, 60, and 90. Vibriocidal assay was performed on samples collected at all five time points. Our results showed that anti-LPS and vibriocidal antibody titers increased at day 14 after re-vaccination and decreased gradually at 28, 60, and 90 days across all the groups. Seroconversion rates were generally comparable in all treatment arms. We therefore conclude that vibriocidal antibody titers generated in response to re-vaccination still wane quickly, irrespective of previous vaccination status. However, despite the observed decline, the levels of vibriocidal antibodies remained elevated over baseline values across all groups, an important aspect for Zambia where there is no empirical evidence as to the ideal time for re-vaccination.