Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-5 (of 5 Records) |
Query Trace: Atieno E[original query] |
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Could less be more? Accounting for fractional-dose regimens and different number of vaccine doses when measuring the impact of the RTS, S/AS01E malaria vaccine
Westercamp N , Osei-Tutu L , Schuerman L , Kariuki SK , Bollaerts A , Lee CK , Samuels AM , Ockenhouse C , Bii DK , Adjei S , Oneko M , Lievens M , Attobrah Sarfo MA , Atieno C , Bakari A , Sang T , Kotoh-Mortty MF , Otieno K , Roman F , Buabeng PBY , Ntiamoah Y , Ansong D , Agbenyega T , Ofori-Anyinam O . J Infect Dis 2024 BACKGROUND: The RTS, S/AS01E malaria vaccine (RTS, S) is recommended for children in moderate-to-high Plasmodium falciparum malaria transmission areas. This phase 2b trial (NCT03276962) evaluates RTS, S fractional- and full-dose regimens in Ghana and Kenya. METHODS: 1500 children aged 5-17 months were randomised (1:1:1:1:1) to receive RTS, S or rabies control vaccine. RTS, S groups received two full RTS, S doses at month (M)0/M1 followed by either full (groups R012-20, R012-14-26) or fractional (1/5) doses (groups Fx012-14-26, Fx017-20-32). RESULTS: At M32 post-first dose, vaccine efficacy (VE) against clinical malaria (all episodes) ranged from 38% (R012-20; 95%CI: 24-49) to 53% (R012-14-26; 95%CI: 42-62). Vaccine impact estimates (cumulative number of malaria cases averted/1000 children vaccinated) were 1344 (R012-20), 2450 (R012-14-26), 2273 (Fx012-14-26), 2112 (Fx017-20-32). To account for differences in vaccine volume (fractional- versus full-dose), in a post-hoc analysis, we also estimated cases averted/1000 RTS, S full-dose equivalents: 336 (R012-20), 490 (R012-14-26), 874 (Fx012-14-26), 880 (Fx017-20-32). CONCLUSIONS: VE against clinical malaria was similar in all RTS, S groups. Vaccine impact accounting for full-dose equivalence suggests that using fractional-dose regimens could be a viable dose-sparing strategy. If borne out through trial end (M50), these observations underscore the means to reduce cost per regimen with a goal of maximising impact and optimising supply. |
Efficacy of RTS,S/AS01(E) malaria vaccine administered according to different full, fractional, and delayed third or early fourth dose regimens in children aged 5-17 months in Ghana and Kenya: an open-label, phase 2b, randomised controlled trial
Samuels AM , Ansong D , Kariuki SK , Adjei S , Bollaerts A , Ockenhouse C , Westercamp N , Lee CK , Schuerman L , Bii DK , Osei-Tutu L , Oneko M , Lievens M , Attobrah Sarfo MA , Atieno C , Morelle D , Bakari A , Sang T , Jongert E , Kotoh-Mortty MF , Otieno K , Roman F , Buabeng PBY , Ntiamoah Y , Ofori-Anyinam O , Agbenyega T . Lancet Infect Dis 2022 22 (9) 1329-1342 BACKGROUND: Controlled infection studies in malaria-naive adults suggest increased vaccine efficacy for fractional-dose versus full-dose regimens of RTS,S/AS01. We report first results of an ongoing trial assessing different fractional-dose regimens in children, in natural exposure settings. METHODS: This open-label, phase 2b, randomised controlled trial is conducted at the Malaria Research Center, Agogo, Ashanti Region (Ghana), and the Kenya Medical Research Institute and the US Centers for Disease Control and Prevention site in Siaya County (Kenya). We enrolled children aged 5-17 months without serious acute or chronic illness who had previously received three doses of diphtheria, tetanus, pertussis, and hepatitis B vaccine and at least three doses of oral polio vaccine. Children were randomly assigned (1:1:1:1:1) using a web-based randomisation system with a minimisation procedure accounting for centre to receive rabies control vaccine (M012 schedule) or two full doses of RTS,S/AS01(E) at month 0 and month 1, followed by either full doses at months 2 and 20 (group R012-20 [standard regimen]), full doses at months 2, 14, 26, and 38 (R012-14), fractional doses at months 2, 14, 26, and 38 (Fx012-14), or fractional doses at months 7, 20, and 32 (Fx017-20). The fractional doses were administered as one fifth (0·1 mL) of the full RTS,S dose (0·5 mL) after reconstitution. All vaccines were administered by intramuscular injection in the left deltoid. The primary outcome was occurrence of clinical malaria cases from month 2·5 until month 14 for the Fx012-14 group versus the pooled R012-14 and R012-20 groups in the per-protocol set. We assessed incremental vaccine efficacy of the Fx012-14 group versus the pooled R012-14 and R012-20 group over 12 months after dose three. Safety was assessed in all children who received at least one vaccine dose. This trial is registered with ClinicalTrials.gov, NCT03276962. FINDINGS: Between Sept 28, 2017, and Sept 25, 2018, 2157 children were enrolled, of whom 1609 were randomly assigned to a treatment group (322 to each RTS,S/AS01(E) group and 321 to the rabies vaccine control group). 1500 children received at least one study vaccine dose and the per-protocol set comprised 1332 children. Over 12 months after dose three, the incremental vaccine efficacy in the Fx012-14 group versus the pooled R012-14 and R12-20 groups was -21% (95% CI -57 to 7; p=0·15). Up to month 21, serious adverse events occurred in 48 (16%) of 298 children in the R012-20 group, 45 (15%) of 294 in the R012-14 group, 47 (15%) of 304 in the Fx012-14 group, 62 (20%) of 311 in the Fx017-20 group, and 71 (24%) of 293 in the control group, with no safety signals observed. INTERPRETATION: The Fx012-14 regimen was not superior to the standard regimen over 12 months after dose three. All RTS,S/AS01(E) regimens provided substantial, similar protection against clinical malaria, suggesting potential flexibility in the recommended dosing regimen and schedule. This, and the effect of annual boosters, will be further evaluated through 50 months of follow-up. FUNDING: GlaxoSmithKline Biologicals; PATH's Malaria Vaccine Initiative. |
The impact of supply-side and demand-side interventions on use of antenatal and maternal services in western Kenya: a qualitative study
Hirai M , Morris J , Luoto J , Ouda R , Atieno N , Quick R . BMC Pregnancy Childbirth 2020 20 (1) 453 BACKGROUND: Antenatal care (ANC) and delivery by skilled providers have been well recognized as effective strategies to prevent maternal and neonatal mortality. ANC and delivery services at health facilities, however, have been underutilized in Kenya. One potential strategy to increase the demand for ANC services is to provide health interventions as incentives for pregnant women. In 2013, an integrated ANC program was implemented in western Kenya to promote ANC visits by addressing both supply- and demand-side factors. Supply-side interventions included nurse training and supplies for obstetric emergencies and neonatal resuscitation. Demand-side interventions included SMS text messages with appointment reminders and educational contents, group education sessions, and vouchers to purchase health products. METHODS: To explore pregnant mothers' experiences with the intervention, ANC visits, and delivery, we conducted focus group discussions (FGDs) at pre- and post-intervention. A total of 19 FGDs were held with pregnant mothers, nurses, and community health workers (CHWs) during the two assessment periods. We performed thematic analyses to highlight study participants' perceptions and experiences. RESULTS: FGD data revealed that pregnant women perceived the risks of home-based delivery, recognized the benefits of facility-based delivery, and were motivated by the incentives to seek care despite barriers to care that included poverty, lack of transport, and poor treatment by nurses. Nurses also perceived the value of incentives to attract women to care but described obstacles to providing health care such as overwork, low pay, inadequate supplies and equipment, and insufficient staff. CHWs identified the utility and limitations of text messages for health education. CONCLUSIONS: Future interventions should ensure that adequate workforce, training, and supplies are in place to respond to increased demand for maternal and child health services stimulated by incentive programs. |
Can incentives reduce the barriers to use of antenatal care and delivery services in Kenya?: Results of a qualitative inquiry
Fleming E , Gaines J , O'Connor K , Ogutu J , Atieno N , Atieno S , Kamb ML , Quick R . J Health Care Poor Underserved 2017 28 (1) 153-174 A qualitative inquiry was used to assess if incentives consisting of a hygiene kit, protein-fortified flour, and delivery kit reduced barriers to antenatal care and delivery services in Nyanza Province, Kenya. We conducted 40 interviews (baseline: five nurses, six mothers, one focus group of five mothers; follow-up: nine nurses, 19 mothers) to assess perceptions of these services. Mothers and nurses identified poor quality of care, fear of HIV diagnosis and stigma, inadequate transport, and cost of care as barriers. Nurses believed incentives encouraged women to use services; mothers described wanting good birth outcomes as their motivation. While barriers to care did not change during the study, incentives may have increased service use. These findings suggest that structural improvements-upgraded infrastructure, adequate staffing, improved treatment of women by nurses, low or no-cost services, and provision of transport-could increase satisfaction with and use of services, improving maternal and infant health. |
'A bite before bed': exposure to malaria vectors outside the times of net use in the highlands of western Kenya
Cooke MK , Kahindi SC , Oriango RM , Owaga C , Ayoma E , Mabuka D , Nyangau D , Abel L , Atieno E , Awuor S , Drakeley C , Cox J , Stevenson J . Malar J 2015 14 (1) 259 BACKGROUND: The human population in the highlands of Nyanza Province, western Kenya, is subject to sporadic epidemics of Plasmodium falciparum. Indoor residual spraying (IRS) and long-lasting insecticide treated nets (LLINs) are used widely in this area. These interventions are most effective when Anopheles rest and feed indoors and when biting occurs at times when individuals use LLINs. It is therefore important to test the current assumption of vector feeding preferences, and late night feeding times, in order to estimate the extent to which LLINs protect the inhabitants from vector bites. METHODS: Mosquito collections were made for six consecutive nights each month between June 2011 and May 2012. CDC light-traps were set next to occupied LLINs inside and outside randomly selected houses and emptied hourly. The net usage of residents, their hours of house entry and exit and times of sleeping were recorded and the individual hourly exposure to vectors indoors and outdoors was calculated. Using these data, the true protective efficacy of nets (P*), for this population was estimated, and compared between genders, age groups and from month to month. RESULTS: Primary vector species (Anopheles funestus s.l. and Anopheles arabiensis) were more likely to feed indoors but the secondary vector Anopheles coustani demonstrated exophagic behaviour (p < 0.05). A rise in vector biting activity was recorded at 19:30 outdoors and 18:30 indoors. Individuals using LLINs experienced a moderate reduction in their overall exposure to malaria vectors from 1.3 to 0.47 bites per night. The P* for the population over the study period was calculated as 51% and varied significantly with age and season (p < 0.01). CONCLUSIONS: In the present study, LLINs offered the local population partial protection against malaria vector bites. It is likely that P* would be estimated to be greater if the overall suppression of the local vector population due to widespread community net use could be taken into account. However, the overlap of early biting habit of vectors and human activity in this region indicates that additional methods of vector control are required to limit transmission. Regular surveillance of both vector behaviour and domestic human-behaviour patterns would assist the planning of future control interventions in this region. |
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