Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-7 (of 7 Records) |
Query Trace: Kayembe L[original query] |
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Analysis of the yearly transition function in measles disease modeling
Davila-Payan CS , Hill A , Kayembe L , Alexander JP , Lynch M , Pallas SW . Stat Med 2023 Globally, there were an estimated 9.8 million measles cases and 207 500 measles deaths in 2019. As the effort to eliminate measles around the world continues, modeling remains a valuable tool for public health decision-makers and program implementers. This study presents a novel approach to the use of a yearly transition function that formulates mathematically the vaccine schedules for different age groups while accounting for the effects of the age of vaccination, the timing of vaccination, and disease seasonality on the yearly number of measles cases in a country. The methodology presented adds to an existing modeling framework and expands its analysis, making its utilization more adjustable for the user and contributing to its conceptual clarity. This article also adjusts for the temporal interaction between vaccination and exposure to disease, applying adjustments to estimated yearly counts of cases and the number of vaccines administered that increase population immunity. These new model features provide the ability to forecast and compare the effects of different vaccination timing scenarios and seasonality of transmission on the expected disease incidence. Although the work presented is applied to the example of measles, it has potential relevance to modeling other vaccine-preventable diseases. |
Nationwide measles and rubella outbreaks in South Sudan, 2019
Peck ME , Maleghemi S , Kayembe L , Hercules M , Anyuon A , Bunga S , McFarland J , Olu O . Open Forum Infect Dis 2023 10 (2) ofad032 BACKGROUND: South Sudan confirmed a measles outbreak in December 2018. An investigation was conducted to assess underlying causes of the outbreak. METHODS: Vaccination coverage and measles surveillance data were analyzed. A suspected measles case had fever, maculopapular rash, and cough or conjunctivitis. A confirmed measles case had generalized maculopapular rash lasting >3 days, a temperature >38°C, and cough or conjunctivitis; or serologic confirmation (anti-measles immunoglobin M [IgM] antibody detection) in serum samples collected ≤30 days from rash onset. A confirmed rubella case tested measles IgM-negative and rubella IgM-positive. RESULTS: Nationwide, 3727 suspected measles cases were reported in 2019. Seventy-five percent of all suspected measles cases were in children aged <5 years. Thirty-six percent of patients with suspected measles were admitted to the hospital, and 36 measles-related deaths were reported. Among cases, 922 (25%) were tested for measles; of these, 317 (34%) were measles IgM-positive. Among cases that tested measles IgM-negative, 149 (33%) were rubella IgM-positive. Immunization coverage for 1 dose of measles-containing vaccine (MCV) varied by state, ranging from 6% to 67%. CONCLUSIONS: Measles and rubella remain public health problems in South Sudan. To reduce measles incidence, South Sudan needs to achieve >95% coverage with 2 doses of MCV. |
Use of a rapid digital microfluidics-powered immunoassay for assessing measles and rubella infection and immunity in outbreak settings in the Democratic Republic of the Congo
Knipes AK , Summers A , Sklavounos AA , Lamanna J , de Campos RPS , Narahari T , Dixon C , Fobel R , Ndjakani YD , Lubula L , Magazani A , Muyembe JJ , Lay Y , Pukuta E , Waku-Kouomou D , Hao L , Kayembe JK , Fobel C , Dahmer J , Lee A , Ho M , Valenzuela JGC , Rackus DG , Shih R , Seale B , Chang A , Paluku G , Rota PA , Wheeler AR , Scobie HM . PLoS One 2022 17 (12) e0278749 The Democratic Republic of the Congo (DRC) has a high measles incidence despite elimination efforts and has yet to introduce rubella vaccine. We evaluated the performance of a prototype rapid digital microfluidics powered (DMF) enzyme-linked immunoassay (ELISA) assessing measles and rubella infection, by testing for immunoglobulin M (IgM), and immunity from natural infection or vaccine, by testing immunoglobulin G (IgG), in outbreak settings. Field evaluations were conducted during September 2017, in Kinshasa province, DRC. Blood specimens were collected during an outbreak investigation of suspected measles cases and tested for measles and rubella IgM and IgG using the DMF-ELISA in the field. Simultaneously, a household serosurvey for measles and rubella IgG was conducted in a recently confirmed measles outbreak area. DMF-ELISA results were compared with reference ELISA results tested at DRC's National Public Health Laboratory and the US Centers for Disease Control and Prevention. Of 157 suspected measles cases, rubella IgM was detected in 54% while measles IgM was detected in 13%. Measles IgG-positive cases were higher among vaccinated persons (87%) than unvaccinated persons (72%). In the recent measles outbreak area, measles IgG seroprevalence was 93% overall, while rubella seroprevalence was lower for children (77%) than women (98%). Compared with reference ELISA, DMF-ELISA sensitivity and specificity were 82% and 78% for measles IgG; 88% and 89% for measles IgM; 85% and 85% for rubella IgG; and 81% and 83% for rubella IgM, respectively. Rubella infection was detected in more than half of persons meeting the suspected measles case definition during a presumed measles outbreak, suggesting substantial unrecognized rubella incidence, and highlighting the need for rubella vaccine introduction into the national schedule. The performance of the DMF-ELISA suggested that this technology can be used to develop rapid diagnostic tests for measles and rubella. |
COVID-19 Vaccine Effectiveness Against Progression to In-Hospital Mortality in Zambia, 2021-2022.
Chanda D , Hines JZ , Itoh M , Fwoloshi S , Minchella PA , Zyambo KD , Sivile S , Kampamba D , Chirwa B , Chanda R , Mutengo K , Kayembe MF , Chewe W , Chipimo P , Mweemba A , Agolory S , Mulenga LB . Open Forum Infect Dis 2022 9 (9) ofac469 BACKGROUND: Coronavirus disease 2019 (COVID-19) vaccines are highly effective for reducing severe disease and mortality. However, vaccine effectiveness data are limited from Sub-Saharan Africa. We report COVID-19 vaccine effectiveness against progression to in-hospital mortality in Zambia. METHODS: We conducted a retrospective cohort study among admitted patients at 8 COVID-19 treatment centers across Zambia during April 2021 through March 2022, when the Delta and Omicron variants were circulating. Patient demographic and clinical information including vaccination status and hospitalization outcome (discharged or died) were collected. Multivariable logistic regression was used to assess the odds of in-hospital mortality by vaccination status, adjusted for age, sex, number of comorbid conditions, disease severity, hospitalization month, and COVID-19 treatment center. Vaccine effectiveness of 1 vaccine dose was calculated from the adjusted odds ratio. RESULTS: Among 1653 patients with data on their vaccination status and hospitalization outcome, 365 (22.1%) died. Overall, 236 (14.3%) patients had received 1 vaccine dose before hospital admission. Of the patients who had received 1 vaccine dose, 22 (9.3%) died compared with 343 (24.2%) among unvaccinated patients (P < .01). The median time since receipt of a first vaccine dose (interquartile range) was 52.5 (28-107) days. Vaccine effectiveness for progression to in-hospital mortality among hospitalized patients was 64.8% (95% CI, 42.3%-79.4%). CONCLUSIONS: Among patients admitted to COVID-19 treatment centers in Zambia, COVID-19 vaccination was associated with lower progression to in-hospital mortality. These data are consistent with evidence from other countries demonstrating the benefit of COVID-19 vaccination against severe complications. Vaccination is a critical tool for reducing the consequences of COVID-19 in Zambia. |
Feasibility of measles and rubella vaccination programmes for disease elimination: a modelling study
Winter AK , Lambert B , Klein D , Klepac P , Papadopoulos T , Truelove S , Burgess C , Santos H , Knapp JK , Reef SE , Kayembe LK , Shendale S , Kretsinger K , Lessler J , Vynnycky E , McCarthy K , Ferrari M , Jit M . Lancet Glob Health 2022 10 (10) e1412-e1422 BACKGROUND: Marked reductions in the incidence of measles and rubella have been observed since the widespread use of the measles and rubella vaccines. Although no global goal for measles eradication has been established, all six WHO regions have set measles elimination targets. However, a gap remains between current control levels and elimination targets, as shown by large measles outbreaks between 2017 and 2019. We aimed to model the potential for measles and rubella elimination globally to inform a WHO report to the 73rd World Health Assembly on the feasibility of measles and rubella eradication. METHODS: In this study, we modelled the probability of measles and rubella elimination between 2020 and 2100 under different vaccination scenarios in 93 countries of interest. We evaluated measles and rubella burden and elimination across two national transmission models each (Dynamic Measles Immunisation Calculation Engine [DynaMICE], Pennsylvania State University [PSU], Johns Hopkins University, and Public Health England models), and one subnational measles transmission model (Institute for Disease Modeling model). The vaccination scenarios included a so-called business as usual approach, which continues present vaccination coverage, and an intensified investment approach, which increases coverage into the future. The annual numbers of infections projected by each model, country, and vaccination scenario were used to explore if, when, and for how long the infections would be below a threshold for elimination. FINDINGS: The intensified investment scenario led to large reductions in measles and rubella incidence and burden. Rubella elimination is likely to be achievable in all countries and measles elimination is likely in some countries, but not all. The PSU and DynaMICE national measles models estimated that by 2050, the probability of elimination would exceed 75% in 14 (16%) and 36 (39%) of 93 modelled countries, respectively. The subnational model of measles transmission highlighted inequity in routine coverage as a likely driver of the continuance of endemic measles transmission in a subset of countries. INTERPRETATION: To reach regional elimination goals, it will be necessary to innovate vaccination strategies and technologies that increase spatial equity of routine vaccination, in addition to investing in existing surveillance and outbreak response programmes. FUNDING: WHO, Gavi, the Vaccine Alliance, US Centers for Disease Control and Prevention, and the Bill & Melinda Gates Foundation. |
High prevalence of hypertension and placental insufficiency, but no in utero HIV transmission, among women on HAART with stillbirths in Botswana
Shapiro RL , Souda S , Parekh N , Binda K , Kayembe M , Lockman S , Svab P , Babitseng O , Powis K , Jimbo W , Creek T , Makhema J , Essex M , Roberts DJ . PLoS One 2012 7 (2) e31580 BACKGROUND: Increased stillbirth rates occur among HIV-infected women, but no studies have evaluated the pathological basis for this increase, or whether highly active antiretroviral therapy (HAART) influences the etiology of stillbirths. It is also unknown whether HIV infection of the fetus is associated with stillbirth. METHODS: HIV-infected women and a comparator group of HIV-uninfected women who delivered stillbirths were enrolled at the largest referral hospital in Botswana between January and November 2010. Obstetrical records, including antiretroviral use in pregnancy, were extracted at enrollment. Verbal autopsies; maternal HIV, CD4 and HIV RNA testing; stillbirth HIV PCR testing; and placental pathology (blinded to HIV and treatment status) were performed. RESULTS: Ninety-nine stillbirths were evaluated, including 62 from HIV-infected women (34% on HAART from conception, 8% on HAART started in pregnancy, 23% on zidovudine started in pregnancy, and 35% on no antiretrovirals) and 37 from a comparator group of HIV-uninfected women. Only 2 (3.7%) of 53 tested stillbirths from HIV-infected women were HIV PCR positive, and both were born to women not receiving HAART. Placental insufficiency associated with hypertension accounted for most stillbirths. Placental findings consistent with chronic hypertension were common among HIV-infected women who received HAART and among HIV-uninfected women (65% vs. 54%, p = 0.37), but less common among HIV-infected women not receiving HAART (28%, p = 0.003 vs. women on HAART). CONCLUSIONS: In utero HIV infection was rarely associated with stillbirths, and did not occur among women receiving HAART. Hypertension and placental insufficiency were associated with most stillbirths in this tertiary care setting. |
HIV infection among internally displaced women and women residing in river populations along the Congo River, Democratic Republic of Congo
Kim AA , Malele F , Kaiser R , Mama N , Kinkela T , Mantshumba JC , Hynes M , De Jesus S , Musema G , Kayembe PK , Hawkins Reed K , Diaz T . AIDS Behav 2009 13 (5) 914-20 We conducted a reproductive health assessment among women aged 15-49 years residing in an internally displaced persons (IDP) camp and surrounding river populations in the Democratic Republic of Congo. After providing informed consent, participants were administered a behavioral questionnaire on demographics, sexual risk, reproductive health behavior, and a history of gender based violence. Participants provided a blood specimen for HIV and syphilis testing and were referred to HIV counseling and testing services established for this study to learn their HIV status. HIV prevalence was significantly higher among women in the IDP population compared to women in the river population. Sexually transmitted infection symptoms in the past 12 months and a history of sexual violence during the conflict were associated with HIV infection the river and IDP population, respectively. Targeted prevention, care, and treatment services are urgently needed for the IDP population and surrounding host communities during displacement and resettlement. |
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