5 results on '"Walker PGT"'
Search Results
2. Using mortuary and burial data to place COVID-19 in Lusaka, Zambia within a global context.
- Author
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Sheppard RJ, Watson OJ, Pieciak R, Lungu J, Kwenda G, Moyo C, Chanda SL, Barnsley G, Brazeau NF, Gerard-Ursin ICG, Olivera Mesa D, Whittaker C, Gregson S, Okell LC, Ghani AC, MacLeod WB, Del Fava E, Melegaro A, Hines JZ, Mulenga LB, Walker PGT, Mwananyanda L, and Gill CJ
- Subjects
- Humans, SARS-CoV-2, Zambia epidemiology, Burial, Pandemics, COVID-19 epidemiology
- Abstract
Reported COVID-19 cases and associated mortality remain low in many sub-Saharan countries relative to global averages, but true impact is difficult to estimate given limitations around surveillance and mortality registration. In Lusaka, Zambia, burial registration and SARS-CoV-2 prevalence data during 2020 allow estimation of excess mortality and transmission. Relative to pre-pandemic patterns, we estimate age-dependent mortality increases, totalling 3212 excess deaths (95% CrI: 2104-4591), representing an 18.5% (95% CrI: 13.0-25.2%) increase relative to pre-pandemic levels. Using a dynamical model-based inferential framework, we find that these mortality patterns and SARS-CoV-2 prevalence data are in agreement with established COVID-19 severity estimates. Our results support hypotheses that COVID-19 impact in Lusaka during 2020 was consistent with COVID-19 epidemics elsewhere, without requiring exceptional explanations for low reported figures. For more equitable decision-making during future pandemics, barriers to ascertaining attributable mortality in low-income settings must be addressed and factored into discourse around reported impact differences., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
3. Reduction in mobility and COVID-19 transmission.
- Author
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Nouvellet P, Bhatia S, Cori A, Ainslie KEC, Baguelin M, Bhatt S, Boonyasiri A, Brazeau NF, Cattarino L, Cooper LV, Coupland H, Cucunuba ZM, Cuomo-Dannenburg G, Dighe A, Djaafara BA, Dorigatti I, Eales OD, van Elsland SL, Nascimento FF, FitzJohn RG, Gaythorpe KAM, Geidelberg L, Green WD, Hamlet A, Hauck K, Hinsley W, Imai N, Jeffrey B, Knock E, Laydon DJ, Lees JA, Mangal T, Mellan TA, Nedjati-Gilani G, Parag KV, Pons-Salort M, Ragonnet-Cronin M, Riley S, Unwin HJT, Verity R, Vollmer MAC, Volz E, Walker PGT, Walters CE, Wang H, Watson OJ, Whittaker C, Whittles LK, Xi X, Ferguson NM, and Donnelly CA
- Subjects
- Algorithms, COVID-19 epidemiology, COVID-19 virology, Communicable Disease Control statistics & numerical data, Global Health, Humans, Models, Theoretical, Physical Distancing, Quarantine methods, SARS-CoV-2 physiology, COVID-19 transmission, Communicable Disease Control methods, Pandemics prevention & control, SARS-CoV-2 isolation & purification
- Abstract
In response to the COVID-19 pandemic, countries have sought to control SARS-CoV-2 transmission by restricting population movement through social distancing interventions, thus reducing the number of contacts. Mobility data represent an important proxy measure of social distancing, and here, we characterise the relationship between transmission and mobility for 52 countries around the world. Transmission significantly decreased with the initial reduction in mobility in 73% of the countries analysed, but we found evidence of decoupling of transmission and mobility following the relaxation of strict control measures for 80% of countries. For the majority of countries, mobility explained a substantial proportion of the variation in transmissibility (median adjusted R-squared: 48%, interquartile range - IQR - across countries [27-77%]). Where a change in the relationship occurred, predictive ability decreased after the relaxation; from a median adjusted R-squared of 74% (IQR across countries [49-91%]) pre-relaxation, to a median adjusted R-squared of 30% (IQR across countries [12-48%]) post-relaxation. In countries with a clear relationship between mobility and transmission both before and after strict control measures were relaxed, mobility was associated with lower transmission rates after control measures were relaxed indicating that the beneficial effects of ongoing social distancing behaviours were substantial.
- Published
- 2021
- Full Text
- View/download PDF
4. Modelling the incremental benefit of introducing malaria screening strategies to antenatal care in Africa.
- Author
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Walker PGT, Cairns M, Slater H, Gutman J, Kayentao K, Williams JE, Coulibaly SO, Khairallah C, Taylor S, Meshnick SR, Hill J, Mwapasa V, Kalilani-Phiri L, Bojang K, Kariuki S, Tagbor H, Griffin JT, Madanitsa M, Ghani ACH, Desai M, and Ter Kuile FO
- Subjects
- Antimalarials therapeutic use, Drug Combinations, Female, Health Policy, Humans, Malaria, Falciparum drug therapy, Parasitic Sensitivity Tests, Plasmodium falciparum drug effects, Pregnancy, Pregnancy Complications, Parasitic drug therapy, Pregnancy Trimester, First, Pyrimethamine therapeutic use, Sulfadoxine therapeutic use, Tanzania, World Health Organization, Malaria, Falciparum diagnosis, Malaria, Falciparum prevention & control, Mass Screening methods, Pregnancy Complications, Parasitic prevention & control, Prenatal Care methods
- Abstract
Plasmodium falciparum in pregnancy is a major cause of adverse pregnancy outcomes. We combine performance estimates of standard rapid diagnostic tests (RDT) from trials of intermittent screening and treatment in pregnancy (ISTp) with modelling to assess whether screening at antenatal visits improves upon current intermittent preventative therapy with sulphadoxine-pyrimethamine (IPTp-SP). We estimate that RDTs in primigravidae at first antenatal visit are substantially more sensitive than in non-pregnant adults (OR = 17.2, 95% Cr.I. 13.8-21.6), and that sensitivity declines in subsequent visits and with gravidity, likely driven by declining susceptibility to placental infection. Monthly ISTp with standard RDTs, even with highly effective drugs, is not superior to monthly IPTp-SP. However, a hybrid strategy, recently adopted in Tanzania, combining testing and treatment at first visit with IPTp-SP may offer benefit, especially in areas with high-grade SP resistance. Screening and treatment in the first trimester, when IPTp-SP is contraindicated, could substantially improve pregnancy outcomes.
- Published
- 2020
- Full Text
- View/download PDF
5. Estimating spatiotemporally varying malaria reproduction numbers in a near elimination setting.
- Author
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Routledge I, Chevéz JER, Cucunubá ZM, Rodriguez MG, Guinovart C, Gustafson KB, Schneider K, Walker PGT, Ghani AC, and Bhatt S
- Subjects
- Basic Reproduction Number, El Salvador epidemiology, Endemic Diseases prevention & control, Epidemiological Monitoring, Humans, Incidence, Likelihood Functions, Malaria epidemiology, Malaria prevention & control, Malaria, Falciparum epidemiology, Malaria, Falciparum prevention & control, Malaria, Falciparum transmission, Malaria, Vivax epidemiology, Malaria, Vivax prevention & control, Malaria, Vivax transmission, Risk Factors, Time Factors, Malaria transmission
- Abstract
In 2016 the World Health Organization identified 21 countries that could eliminate malaria by 2020. Monitoring progress towards this goal requires tracking ongoing transmission. Here we develop methods that estimate individual reproduction numbers and their variation through time and space. Individual reproduction numbers, R
c , describe the state of transmission at a point in time and differ from mean reproduction numbers, which are averages of the number of people infected by a typical case. We assess elimination progress in El Salvador using data for confirmed cases of malaria from 2010 to 2016. Our results demonstrate that whilst the average number of secondary malaria cases was below one (0.61, 95% CI 0.55-0.65), individual reproduction numbers often exceeded one. We estimate a decline in Rc between 2010 and 2016. However we also show that if importation is maintained at the same rate, the country may not achieve malaria elimination by 2020.- Published
- 2018
- Full Text
- View/download PDF
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