Browsing by Author "Kariuki, Simon"

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    Malaria hospitalisation in East Africa: age, phenotype and transmission intensity
    (BMC medicine, 2022) Kamau, Alice; Paton, Robert S.; Akech, Samuel; Mpimbaza, Arthur; Khazenzi, Cynthia; Ogero, Morris; Mumo, Eda; Alegana, Victor A.; Agweyu, Ambrose; Mturi, Neema; Mohammed, Shebe; Bigogo, Godfrey; Audi, Allan; Kapisi, James; Sserwanga, Asadu; Namuganga, Jane F.; Kariuki, Simon; Otieno, Nancy A.; Nyawanda, Bryan O.; Olotu, Ally; Salim, Nahya; Athuman, Thabit; Abdulla, Salim; Mohamed, Amina F.; Mtove, George; Reyburn, Hugh; Gupta, Sunetra; Lourenço, José; Bejon, Philip; Snow, Robert W.
    Understanding the age patterns of disease is necessary to target interventions to maximise costeffective impact. New malaria chemoprevention and vaccine initiatives target young children attending routine immunisation services. Here we explore the relationships between age and severity of malaria hospitalisation versus malaria transmission intensity. Methods: Clinical data from 21 surveillance hospitals in East Africa were reviewed. Malaria admissions aged 1 month to 14 years from discrete administrative areas since 2006 were identified. Each site-time period was matched to a model estimated community-based age-corrected parasite prevalence to provide predictions of prevalence in childhood (PfPR2–10). Admission with all-cause malaria, severe malaria anaemia (SMA), respiratory distress (RD) and cerebral malaria (CM) were analysed as means and predicted probabilities from Bayesian generalised mixed models. Results: 52,684 malaria admissions aged 1 month to 14 years were described at 21 hospitals from 49 site-time locations where PfPR2–10 varied from < 1 to 48.7%. Twelve site-time periods were described as low transmission (PfPR2–10 < 5%), five low-moderate transmission (PfPR2–10 5–9%), 20 moderate transmission (PfPR2–10 10–29%) and 12 high transmission (PfPR2–10 ≥ 30%). The majority of malaria admissions were below 5 years of age (69–85%) and rare among children aged 10–14 years (0.7–5.4%) across all transmission settings. The mean age of all-cause malaria hospitalisation was 49.5 months (95% CI 45.1, 55.4) under low transmission compared with 34.1 months (95% CI 30.4, 38.3) at high transmission, with similar trends for each severe malaria phenotype. CM presented among older children at a mean of 48.7 months compared with 39.0 months and 33.7 months for SMA and RD, respectively. In moderate and high transmission settings, 34% and 42% of the children were aged between 2 and 23 months and so within the age range targeted by chemoprevention or vaccines. Conclusions: Targeting chemoprevention or vaccination programmes to areas where community-based parasite prevalence is ≥10% is likely to match the age ranges covered by interventions (e.g. intermittent presumptive treatment in infancy to children aged 2–23 months and current vaccine age eligibility and duration of efficacy) and the age ranges of highest disease burden.
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    Policy uptake and implementation of the RTS,S/AS01 malaria vaccine in sub-Saharan African countries: status 2 years following the WHO recommendation
    (BMJ Publishing Group Ltd, 2024-04) Osoro, Caroline Bonareri; Ochodo, Eleanor; Kwambai, Titus K; Otieno, Jenifer Akoth; Were, Lisa; Sagam, Caleb Kimutai; Owino, Eddy Johnson; Kariuki, Simon; ter Kuile, Feiko O; Hill, Jenny
    In October 2021, the WHO recommended the world’s first malaria vaccine—RTS,S/AS01—to prevent malaria in children living in areas with moderate-to-high transmission in sub-Saharan Africa (SSA). A second malaria vaccine, R21/Matrix-M, was recommended for use in October 2023 and added to the WHO list of prequalified vaccines in December 2023. This study analysis assessed the country status of implementation and delivery strategies for RTS,S/AS01 by searching websites for national malaria policies, guidelines and related documents. Direct contact with individuals working in malaria programmes was made to obtain documents not publicly available. 10 countries had documents with information relating to malaria vaccine implementation, 7 referencing RTS,S/AS01 and 3 (Burkina Faso, Kenya and Nigeria) referencing RTS,S/AS01 and R21/Matrix-M. Five other countries reported plans for malaria vaccine roll-out without specifying which vaccine. Ghana, Kenya and Malawi, which piloted RTS,S/AS01, have now integrated the vaccine into routine immunisation services. Cameroon and Burkina Faso are the first countries outside the pilot countries to incorporate the vaccine into national immunisation services. Uganda plans a phased RTS,S/AS01 introduction, while Guinea plans to first pilot RTS,S/AS01 in five districts. The RTS,S/AS01 schedule varied by country, with the first dose administered at 5 or 6 months in all countries but the fourth dose at either 18, 22 or 24 months. SSA countries have shown widespread interest in rolling out the malaria vaccine, the Global Alliance for Vaccines and Immunization having approved financial support for 20 of 30 countries which applied as of March 2024. Limited availability of RTS,S/AS01 means that some approved countries will not receive the required doses. Vaccine availability and equity must be addressed even as R21/Matrix-M becomes available. ProQuest Public Health
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    Pregnancy outcomes after first-trimester treatment with artemisinin derivatives versus non-artemisinin antimalarials: a systematic review and individual patient data meta-analysis
    (The Lancet, 2022) Saito, Makoto; McGready, Rose; Tinto, Halidou; Rouamba, Toussaint; Mosha, Dominic; Rulisa, Stephen; Kariuki, Simon; Desai, Meghna; Manyando, Christine; Njunju, Eric M.; Sevene, Esperanca; Vala, Anifa; Augusto, Orvalho; Clerk, Christine; Were, Edwin; Mrema, Sigilbert; Kisinza, William; Byamugisha, Josaphat; Kagawa, Mike; Singlovic, Jan; Yore, Mackensie; Maria van Eijk, Anna; Mehta, Ushma; Stergachis, Andy; Hill, Jenny; Stepniewska, Kasia; Gomes, Melba; Guérin, Philippe J.; Nosten, Francois; ter Kuile, Feiko O.; Dellicour, Stephanie
    Malaria in the first trimester of pregnancy is associated with adverse pregnancy outcomes. Artemisininbased combination therapies (ACTs) are a highly effective, first-line treatment for uncomplicated Plasmodium falciparum malaria, except in the first trimester of pregnancy, when quinine with clindamycin is recommended due to concerns about the potential embryotoxicity of artemisinins. We compared adverse pregnancy outcomes after artemisininbased treatment (ABT) versus non-ABTs in the first trimester of pregnancy. Methods For this systematic review and individual patient data (IPD) meta-analysis, we searched MEDLINE, Embase, and the Malaria in Pregnancy Library for prospective cohort studies published between Nov 1, 2015, and Dec 21, 2021, containing data on outcomes of pregnancies exposed to ABT and non-ABT in the first trimester. The results of this search were added to those of a previous systematic review that included publications published up until November, 2015. We included pregnancies enrolled before the pregnancy outcome was known. We excluded pregnancies with missing estimated gestational age or exposure information, multiple gestation pregnancies, and if the fetus was confirmed to be unviable before antimalarial treatment. The primary endpoint was adverse pregnancy outcome, defined as a composite of either miscarriage, stillbirth, or major congenital anomalies. A one-stage IPD meta-analysis was done by use of shared-frailty Cox models. This study is registered with PROSPERO, number CRD42015032371. Findings We identified seven eligible studies that included 12 cohorts. All 12 cohorts contributed IPD, including 34 178 pregnancies, 737 with confirmed first-trimester exposure to ABTs and 1076 with confirmed first-trimester exposure to non-ABTs. Adverse pregnancy outcomes occurred in 42 (5·7%) of 736 ABT-exposed pregnancies compared with 96 (8·9%) of 1074 non-ABT-exposed pregnancies in the first trimester (adjusted hazard ratio [aHR] 0·71, 95% CI 0·49–1·03). Similar results were seen for the individual components of miscarriage (aHR=0·74, 0·47–1·17), stillbirth (aHR=0·71, 0·32–1·57), and major congenital anomalies (aHR=0·60, 0·13–2·87). The risk of adverse pregnancy outcomes was lower with artemether–lumefantrine than with oral quinine in the first trimester of pregnancy (25 [4·8%] of 524 vs 84 [9·2%] of 915; aHR 0·58, 0·36–0·92). Interpretation We found no evidence of embryotoxicity or teratogenicity based on the risk of miscarriage, stillbirth, or major congenital anomalies associated with ABT during the first trimester of pregnancy. Given that treatment with artemether–lumefantrine was associated with fewer adverse pregnancy outcomes than quinine, and because of the known superior tolerability and antimalarial effectiveness of ACTs, artemether–lumefantrine should be considered the preferred treatment for uncomplicated P falciparum malaria in the first trimester. If artemether–lumefantrine is unavailable, other ACTs (except artesunate–sulfadoxine–pyrimethamine) should be preferred to quinine. Continued active pharmacovigilance is warranted.