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1.
PLoS Med ; 20(11): e1004195, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38016000

RESUMO

BACKGROUND: Vaccines have reduced severe disease and death from Coronavirus Disease 2019 (COVID-19). However, with evidence of waning efficacy coupled with continued evolution of the virus, health programmes need to evaluate the requirement for regular booster doses, considering their impact and cost-effectiveness in the face of ongoing transmission and substantial infection-induced immunity. METHODS AND FINDINGS: We developed a combined immunological-transmission model parameterised with data on transmissibility, severity, and vaccine effectiveness. We simulated Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission and vaccine rollout in characteristic global settings with different population age-structures, contact patterns, health system capacities, prior transmission, and vaccine uptake. We quantified the impact of future vaccine booster dose strategies with both ancestral and variant-adapted vaccine products, while considering the potential future emergence of new variants with modified transmission, immune escape, and severity properties. We found that regular boosting of the oldest age group (75+) is an efficient strategy, although large numbers of hospitalisations and deaths could be averted by extending vaccination to younger age groups. In countries with low vaccine coverage and high infection-derived immunity, boosting older at-risk groups was more effective than continuing primary vaccination into younger ages in our model. Our study is limited by uncertainty in key parameters, including the long-term durability of vaccine and infection-induced immunity as well as uncertainty in the future evolution of the virus. CONCLUSIONS: Our modelling suggests that regular boosting of the high-risk population remains an important tool to reduce morbidity and mortality from current and future SARS-CoV-2 variants. Our results suggest that focusing vaccination in the highest-risk cohorts will be the most efficient (and hence cost-effective) strategy to reduce morbidity and mortality.


Assuntos
COVID-19 , Vacinas , Humanos , SARS-CoV-2 , COVID-19/prevenção & controle , Vacinação
2.
Int J Equity Health ; 21(1): 82, 2022 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-35701823

RESUMO

BACKGROUND: Evidence to date has shown that inequality in health, and vaccination coverage in particular, can have ramifications to wider society. However, whilst individual studies have sought to characterise these heterogeneities in immunisation coverage at national level, few have taken a broad and quantitative view of the contributing factors to heterogeneity in immunisation coverage and impact, i.e. the number of cases, deaths, and disability-adjusted life years averted. This systematic review aims to highlight these geographic, demographic, and sociodemographic characteristics through a qualitative and quantitative approach, vital to prioritise and optimise vaccination policies. METHODS: A systematic review of two databases (PubMed and Web of Science) was undertaken using search terms and keywords to identify studies examining factors on immunisation inequality and heterogeneity in vaccination coverage. Inclusion criteria were applied independently by two researchers. Studies including data on key characteristics of interest were further analysed through a meta-analysis to produce a pooled estimate of the risk ratio using a random effects model for that characteristic. RESULTS: One hundred and eight studies were included in this review. We found that inequalities in wealth, education, and geographic access can affect vaccine impact and vaccination dropout. We estimated those living in rural areas were not significantly different in terms of full vaccination status compared to urban areas but noted considerable heterogeneity between countries. We found that females were 3% (95%CI[1%, 5%]) less likely to be fully vaccinated than males. Additionally, we estimated that children whose mothers had no formal education were 28% (95%CI[18%,47%]) less likely to be fully vaccinated than those whose mother had primary level, or above, education. Finally, we found that individuals in the poorest wealth quintile were 27% (95%CI [16%,37%]) less likely to be fully vaccinated than those in the richest. CONCLUSIONS: We found a nuanced picture of inequality in vaccination coverage and access with wealth disparity dominating, and likely driving, other disparities. This review highlights the complex landscape of inequity and further need to design vaccination strategies targeting missed subgroups to improve and recover vaccination coverage following the COVID-19 pandemic. TRIAL REGISTRATION: Prospero, CRD42021261927.


Assuntos
COVID-19 , Vacinas , Criança , Países em Desenvolvimento , Feminino , Humanos , Masculino , Pandemias , Vacinação , Cobertura Vacinal
3.
Clin Infect Dis ; 72(Suppl 3): S140-S145, 2021 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-33909064

RESUMO

BACKGROUND: The World Health Organization previously set goals of controlling morbidity due to schistosomiasis by 2020 and attaining elimination as a public health problem (EPHP) by 2025 (now adjusted to 2030 in the new neglected tropical diseases roadmap). As these milestones are reached, it is important that programs reassess their treatment strategies to either maintain these goals or progress from morbidity control to EPHP and ultimately to interruption of transmission. In this study, we consider different mass drug administration (MDA) strategies to maintain the goals. METHODS: We used 2 independently developed, individual-based stochastic models of schistosomiasis transmission to assess the optimal treatment strategy of a multiyear program to maintain the morbidity control and the EPHP goals. RESULTS: We found that, in moderate-prevalence settings, once the morbidity control and EPHP goals are reached it may be possible to maintain the goals using less frequent MDAs than those that are required to achieve the goals. On the other hand, in some high-transmission settings, if control efforts are reduced after achieving the goals, particularly the morbidity control goal, there is a high chance of recrudescence. CONCLUSIONS: To reduce the risk of recrudescence after the goals are achieved, programs have to re-evaluate their strategies and decide to either maintain these goals with reduced efforts where feasible or continue with at least the same efforts required to reach the goals.


Assuntos
Anti-Helmínticos , Esquistossomose mansoni , Esquistossomose , Animais , Anti-Helmínticos/uso terapêutico , Humanos , Administração Massiva de Medicamentos , Prevalência , Schistosoma mansoni , Esquistossomose/tratamento farmacológico , Esquistossomose mansoni/tratamento farmacológico
4.
Clin Infect Dis ; 72(8): 1463-1466, 2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-32984870

RESUMO

Due to the COVID-19 pandemic, many key neglected tropical disease (NTD) activities have been postponed. This hindrance comes at a time when the NTDs are progressing towards their ambitious goals for 2030. Mathematical modelling on several NTDs, namely gambiense sleeping sickness, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiases (STH), trachoma, and visceral leishmaniasis, shows that the impact of this disruption will vary across the diseases. Programs face a risk of resurgence, which will be fastest in high-transmission areas. Furthermore, of the mass drug administration diseases, schistosomiasis, STH, and trachoma are likely to encounter faster resurgence. The case-finding diseases (gambiense sleeping sickness and visceral leishmaniasis) are likely to have fewer cases being detected but may face an increasing underlying rate of new infections. However, once programs are able to resume, there are ways to mitigate the impact and accelerate progress towards the 2030 goals.


Assuntos
COVID-19 , Medicina Tropical , Humanos , Doenças Negligenciadas/epidemiologia , Pandemias , SARS-CoV-2
5.
BMC Public Health ; 21(1): 2049, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34753437

RESUMO

BACKGROUND: Deaths due to vaccine preventable diseases cause a notable proportion of mortality worldwide. To quantify the importance of vaccination, it is necessary to estimate the burden averted through vaccination. The Vaccine Impact Modelling Consortium (VIMC) was established to estimate the health impact of vaccination. METHODS: We describe the methods implemented by the VIMC to estimate impact by calendar year, birth year and year of vaccination (YoV). The calendar and birth year methods estimate impact in a particular year and over the lifetime of a particular birth cohort, respectively. The YoV method estimates the impact of a particular year's vaccination activities through the use of impact ratios which have no stratification and stratification by activity type and/or birth cohort. Furthermore, we detail an impact extrapolation (IE) method for use between coverage scenarios. We compare the methods, focusing on YoV for hepatitis B, measles and yellow fever. RESULTS: We find that the YoV methods estimate similar impact with routine vaccinations but have greater yearly variation when campaigns occur with the birth cohort stratification. The IE performs well for the YoV methods, providing a time-efficient mechanism for updates to impact estimates. CONCLUSIONS: These methods provide a robust set of approaches to quantify vaccination impact; however it is vital that the area of impact estimation continues to develop in order to capture the full effect of immunisation.


Assuntos
Sarampo , Febre Amarela , Coorte de Nascimento , Humanos , Sarampo/epidemiologia , Sarampo/prevenção & controle , Saúde Pública , Vacinação
6.
J Infect Dis ; 221(Suppl 5): S525-S530, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-31829414

RESUMO

The World Health Organization (WHO) has set elimination as a public health problem (EPHP) as a goal for schistosomiasis. As the WHO treatment guidelines for schistosomiasis are currently under revision, we investigate whether school-based or community-wide treatment strategies are required for achieving the EPHP goal. In low- to moderate-transmission settings with good school enrolment, we find that school-based treatment is sufficient for achieving EPHP. However, community-wide treatment is projected to be necessary in certain high-transmission settings as well as settings with low school enrolment. Hence, the optimal treatment strategy depends on setting-specific factors such as the species present, prevalence prior to treatment, and the age profile of infection.


Assuntos
Administração Massiva de Medicamentos/normas , Schistosoma haematobium , Schistosoma mansoni , Esquistossomose Urinária/tratamento farmacológico , Esquistossomose mansoni/tratamento farmacológico , Adolescente , Adulto , Idoso , Animais , Criança , Pré-Escolar , Serviços de Saúde Comunitária , Humanos , Pessoa de Meia-Idade , Modelos Biológicos , Guias de Prática Clínica como Assunto , Saúde Pública , Esquistossomose Urinária/epidemiologia , Esquistossomose mansoni/epidemiologia , Adulto Jovem
7.
J Infect Dis ; 221(Suppl 5): S499-S502, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32529261

RESUMO

As neglected tropical disease programs look to consolidate the successes of moving towards elimination, we need to understand the dynamics of transmission at low prevalence to inform surveillance strategies for detecting elimination and resurgence. In this special collection, modelling insights are used to highlight drivers of local elimination, evaluate strategies for detecting resurgence, and show the importance of rational spatial sampling schemes for several neglected tropical diseases (specifically schistosomiasis, soil-transmitted helminths, lymphatic filariasis, trachoma, onchocerciasis, visceral leishmaniasis, and gambiense sleeping sickness).


Assuntos
Erradicação de Doenças/estatística & dados numéricos , Doenças Negligenciadas/diagnóstico , Vigilância da População/métodos , Medicina Tropical , Humanos
8.
Clin Infect Dis ; 68(9): 1588-1595, 2019 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-30169566

RESUMO

Community health volunteers (CHVs) are being used within a growing number of healthcare interventions, and they have become a cornerstone for the delivery of mass drug administration within many neglected tropical disease control programs. However, a greater understanding of the methods used to value the unpaid time CHVs contribute to healthcare programs is needed. We outline the two main approaches used to value CHVs' unpaid time (the opportunity cost and the replacement cost approaches). We found that for mass drug administration programs the estimates of the economic costs relating to the CHVs' unpaid time can be significant, with the averages of the different studies varying between US$0.05 and $0.16 per treatment. We estimated that the time donated by CHVs' to the African Programme for Onchocerciasis Control alone would be valued between US$60 and $90 million. There is a need for greater transparency and consistency in the methods used to value CHVs' unpaid time.


Assuntos
Agentes Comunitários de Saúde/economia , Atenção à Saúde/economia , Administração Massiva de Medicamentos/economia , Saúde Pública/economia , Voluntários/estatística & dados numéricos , Humanos
9.
Clin Infect Dis ; 66(8): 1298-1303, 2018 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-29126255

RESUMO

It is recognized that changing the current approaches for the control of the neglected tropical diseases will be needed to reach the World Health Organization's (WHO) 2020 goals. Consequently, it is important that economic evaluations of the alternative approaches are conducted. A vital component of such evaluations is the issue of how the intervention's costs should be incorporated. We discuss this issue-focusing on mass drug administration. We argue that the common approach of assuming an intervention's cost per treatment is constant, regardless of the number of individuals treated, is a misleading way to consider the delivery costs of mass drug administration due to the occurrence of economies/diseconomies of scale and scope. Greater care and consideration are required when the costs are incorporated into such analyses. Without this, these economic evaluations could potentially lead to incorrect policy recommendations.


Assuntos
Administração Massiva de Medicamentos , Análise Custo-Benefício , Custos de Medicamentos , Humanos , Organização Mundial da Saúde
10.
Clin Infect Dis ; 66(suppl_4): S253-S259, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29860285

RESUMO

Background: Considerable efforts have been made to better understand the effectiveness of large-scale preventive chemotherapy therapy for the control of morbidity caused by infection with soil-transmitted helminths (STHs): Ascaris lumbricoides, Trichuris trichiura, and the 2 hookworm species, Necator americanus and Ancylostoma duodenale. Current World Health Organization (WHO) guidelines for STH control include mass drug administration (MDA) programs based on prevalence measurements, aiming at reducing morbidity in pre-school-aged children (pre-SAC) and school-aged children (SAC) by lowering the prevalence of moderate- to heavy-intensity infections to <1%. Methods: We project the likely impact of following the current WHO guidelines and assess whether the WHO morbidity goals will be achieved across a range of transmission settings. We also investigate modifications that could be made to the current WHO treatment guidelines, and project their potential impacts in achieving morbidity and transmission control. Results: While the standard guidelines are sufficient at low transmission levels, community-wide treatment (ie, involving pre-SAC, SAC, and adults) is essential if WHO morbidity goals are to be met in moderate- to high-transmission settings. Moreover, removing the recommendation of decreasing the treatment frequency at midline (5-6 years after the start of MDA) further improves the likelihood of achieving morbidity control in SAC. Conclusions: We meld analyses based on 2 mathematical models of parasite transmission and control by MDA for the dominant STH species, to generate a unified treatment approach applicable across all settings, regardless of which STH infection is most common. We recommend clearly defined changes to the current WHO guidelines.


Assuntos
Albendazol/administração & dosagem , Anti-Helmínticos/administração & dosagem , Helmintíase/prevenção & controle , Helmintos/efeitos dos fármacos , Modelos Teóricos , Guias de Prática Clínica como Assunto , Adulto , Animais , Criança , Pré-Escolar , Feminino , Helmintíase/tratamento farmacológico , Helmintíase/epidemiologia , Helmintíase/transmissão , Humanos , Administração Massiva de Medicamentos , Prevalência , Solo/parasitologia , Organização Mundial da Saúde
11.
Clin Infect Dis ; 66(suppl_4): S245-S252, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29860290

RESUMO

Background: Schistosomiasis remains an endemic parasitic disease affecting millions of people around the world. The World Health Organization (WHO) has set goals of controlling morbidity to be reached by 2020, along with elimination as a public health problem in certain regions by 2025. Mathematical models of parasite transmission and treatment impact have been developed to assist in controlling the morbidity caused by schistosomiasis. These models can inform and guide implementation policy for mass drug administration programs, and help design monitoring and evaluation activities. Methods: We use these models to predict whether the guidelines set by the WHO are on track for achieving their 2020 goal for the control of morbidity, specifically for Schistosoma mansoni. We examine whether programmatic adaptations; namely increases in treatment coverage and/or expansion to adult inclusion in treatment, will improve the likelihood of reaching the WHO goals. Results: We find that in low-prevalence settings, the goals are likely to be attainable under current WHO guidelines, but in moderate to high-prevalence settings, the goals are less likely to be achieved unless treatment coverage is increased and expanded to at least 85% for school-aged children and 40% for adults. Conclusions: To improve the likelihood of reaching the WHO goals, programmatic adaptations are required, particularly for moderate- to high-prevalence settings. Furthermore, improvements in adherence to treatment, potential development of candidate vaccines, and enhanced snail control and WASH (water, sanitation, and hygiene) measures will all assist in achieving the goals.


Assuntos
Doenças Endêmicas/prevenção & controle , Modelos Teóricos , Guias de Prática Clínica como Assunto , Saúde Pública , Esquistossomose/epidemiologia , Animais , Erradicação de Doenças , Objetivos , Humanos , Higiene , Administração Massiva de Medicamentos , Morbidade , Prevalência , Saneamento , Esquistossomose/tratamento farmacológico , Esquistossomose/prevenção & controle , Esquistossomose/transmissão , Organização Mundial da Saúde
14.
Am Nat ; 187(3): 308-19, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26913944

RESUMO

Natural and managed populations are embedded within complex ecological communities, where they face multiple enemies. Experimental studies have shown that the evolution of host defense mechanisms to a focal enemy is impacted by the surrounding enemy community. Theoretically, the evolution of host defenses against a single enemy population, typically parasites, has been widely studied, but only recently has the impact of community interactions on host-parasite evolution been looked at. In this article, we theoretically examine the evolutionary behavior of a host population that must allocate defenses between two enemy populations, parasites and predators, with defense against one enemy constraining defense against the other. We show that in simpler models the composition of the enemy community plays the key role in determining the defense strategy of the hosts, with the hosts building up defenses against the enemy population posing a larger threat. However, this simple driver is shown to break down when there is significant recovery and reproduction from infected hosts. Additionally, we find that most host diversity is likely to occur when there is a combined high risk of infection and predation, in common with experimental studies. Our results therefore provide vital insight into the ecological feedbacks that drive the evolution of host defense against multiple enemy populations.


Assuntos
Evolução Biológica , Interações Hospedeiro-Parasita , Comportamento Predatório , Animais , Cadeia Alimentar , Modelos Biológicos
15.
J Theor Biol ; 365: 104-11, 2015 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-25454010

RESUMO

While theoretical models on the evolution of host defences against disease have been widely studied, the inclusion of predators and community interactions more generally, has often been overlooked. In this paper, we examine a host-parasite model with an additional predator and show that the predator changes the evolutionary behaviour of the host. We find that the hosts maximize their levels of resistance at intermediate predation rates, where the cost of infection and the risk of exposure to disease are both high. We show that this effect is heightened when parasites are highly virulent and when there is strong selective predation. We also show that the potential for evolutionary branching increases with the predation rate for regions where the susceptible and infected hosts coexist with the predator. Hence, our results reveal that there are considerable impacts of adding predators to a population.


Assuntos
Cadeia Alimentar , Interações Hospedeiro-Parasita , Infecções , Modelos Biológicos , Animais
16.
Nat Commun ; 14(1): 4325, 2023 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-37468463

RESUMO

With the ongoing evolution of the SARS-CoV-2 virus updated vaccines may be needed. We fitted a model linking immunity levels and protection to vaccine effectiveness data from England for three vaccines (Oxford/AstraZeneca AZD1222, Pfizer-BioNTech BNT162b2, Moderna mRNA-1273) and two variants (Delta, Omicron). Our model reproduces the observed sustained protection against hospitalisation and death from the Omicron variant over the first six months following dose 3 with the ancestral vaccines but projects a gradual waning to moderate protection after 1 year. Switching the fourth dose to a variant-matched vaccine against Omicron BA.1/2 is projected to prevent nearly twice as many hospitalisations and deaths over a 1-year period compared to administering the ancestral vaccine. This result is sensitive to the degree to which immunogenicity data can be used to predict vaccine effectiveness and uncertainty regarding the impact that infection-induced immunity (not captured here) may play in modifying future vaccine effectiveness.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/genética , Vacina BNT162 , COVID-19/prevenção & controle , ChAdOx1 nCoV-19 , Eficácia de Vacinas , Vacinas contra COVID-19
17.
Lancet Infect Dis ; 22(9): 1293-1302, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35753318

RESUMO

BACKGROUND: The first COVID-19 vaccine outside a clinical trial setting was administered on Dec 8, 2020. To ensure global vaccine equity, vaccine targets were set by the COVID-19 Vaccines Global Access (COVAX) Facility and WHO. However, due to vaccine shortfalls, these targets were not achieved by the end of 2021. We aimed to quantify the global impact of the first year of COVID-19 vaccination programmes. METHODS: A mathematical model of COVID-19 transmission and vaccination was separately fit to reported COVID-19 mortality and all-cause excess mortality in 185 countries and territories. The impact of COVID-19 vaccination programmes was determined by estimating the additional lives lost if no vaccines had been distributed. We also estimated the additional deaths that would have been averted had the vaccination coverage targets of 20% set by COVAX and 40% set by WHO been achieved by the end of 2021. FINDINGS: Based on official reported COVID-19 deaths, we estimated that vaccinations prevented 14·4 million (95% credible interval [Crl] 13·7-15·9) deaths from COVID-19 in 185 countries and territories between Dec 8, 2020, and Dec 8, 2021. This estimate rose to 19·8 million (95% Crl 19·1-20·4) deaths from COVID-19 averted when we used excess deaths as an estimate of the true extent of the pandemic, representing a global reduction of 63% in total deaths (19·8 million of 31·4 million) during the first year of COVID-19 vaccination. In COVAX Advance Market Commitment countries, we estimated that 41% of excess mortality (7·4 million [95% Crl 6·8-7·7] of 17·9 million deaths) was averted. In low-income countries, we estimated that an additional 45% (95% CrI 42-49) of deaths could have been averted had the 20% vaccination coverage target set by COVAX been met by each country, and that an additional 111% (105-118) of deaths could have been averted had the 40% target set by WHO been met by each country by the end of 2021. INTERPRETATION: COVID-19 vaccination has substantially altered the course of the pandemic, saving tens of millions of lives globally. However, inadequate access to vaccines in low-income countries has limited the impact in these settings, reinforcing the need for global vaccine equity and coverage. FUNDING: Schmidt Science Fellowship in partnership with the Rhodes Trust; WHO; UK Medical Research Council; Gavi, the Vaccine Alliance; Bill & Melinda Gates Foundation; National Institute for Health Research; and Community Jameel.


Assuntos
COVID-19 , Vacinas , Vacinas contra COVID-19 , Saúde Global , Humanos , Modelos Teóricos , Vacinação
18.
Lancet Glob Health ; 10(11): e1600-e1611, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36240827

RESUMO

BACKGROUND: In line with movement restrictions and physical distancing essential for the control of the COVID-19 pandemic, WHO recommended postponement of all neglected tropical disease (NTD) control activities that involve community-based surveys, active case finding, and mass drug administration in April, 2020. Following revised guidance later in 2020, and after interruptions to NTD programmes of varying lengths, NTD programmes gradually restarted in the context of an ongoing pandemic. However, ongoing challenges and service gaps have been reported. This study aimed to evaluate the potential effect of the programmatic interruptions and strategies to mitigate this effect. METHODS: For seven NTDs, namely soil-transmitted helminths, schistosomiasis, lymphatic filariasis, onchocerciasis, trachoma, visceral leishmaniasis, and human African trypanosomiasis, we used mathematical transmission models to simulate the effect of programme interruptions on the dynamics of each of these diseases in different endemic settings. We also explored the potential benefit of implementing mitigation strategies, primarily in terms of minimising the delays to control targets. FINDINGS: We show that the effect of the COVID-19-induced interruption in terms of delay to achieving elimination goals might in some cases be much longer than the duration of the interruption. For schistosomiasis, onchocerciasis, trachoma, and visceral leishmaniasis, a mean delay of 2-3 years for a 1-year interruption is predicted in areas of highest prevalence. We also show that these delays can largely be mitigated by measures such as additional mass drug administration or enhanced case-finding. INTERPRETATION: The COVID-19 pandemic has brought infectious disease control to the forefront of global consciousness. It is essential that the NTDs, so long neglected in terms of research and financial support, are not overlooked, and remain a priority in health service planning and funding. FUNDING: Bill & Melinda Gates Foundation, Medical Research Council, and the UK Foreign, Commonwealth & Development Office.


Assuntos
COVID-19 , Leishmaniose Visceral , Oncocercose , Esquistossomose , Tracoma , Medicina Tropical , COVID-19/epidemiologia , COVID-19/prevenção & controle , Humanos , Leishmaniose Visceral/epidemiologia , Doenças Negligenciadas/epidemiologia , Doenças Negligenciadas/prevenção & controle , Oncocercose/prevenção & controle , Pandemias , Esquistossomose/epidemiologia , Esquistossomose/prevenção & controle , Solo , Tracoma/epidemiologia
19.
Vaccine ; 40(31): 4142-4149, 2022 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-35672179

RESUMO

Over the past two decades, vaccination programmes for vaccine-preventable diseases (VPDs) have expanded across low- and middle-income countries (LMICs). However, the rise of COVID-19 resulted in global disruption to routine immunisation activities. Such disruptions could have a detrimental effect on public health, leading to more deaths from VPDs, particularly without mitigation efforts. Hence, as routine immunisation activities resume, it is important to estimate the effectiveness of different approaches for recovery. We apply an impact extrapolation method developed by the Vaccine Impact Modelling Consortium to estimate the impact of COVID-19-related disruptions with different recovery scenarios for ten VPDs across 112 LMICs. We focus on deaths averted due to routine immunisations occurring in the years 2020-2030 and investigate two recovery scenarios relative to a no-COVID-19 scenario. In the recovery scenarios, we assume a 10% COVID-19-related drop in routine immunisation coverage in the year 2020. We then linearly interpolate coverage to the year 2030 to investigate two routes to recovery, whereby the immunization agenda (IA2030) targets are reached by 2030 or fall short by 10%. We estimate that falling short of the IA2030 targets by 10% leads to 11.26% fewer fully vaccinated persons (FVPs) and 11.34% more deaths over the years 2020-2030 relative to the no-COVID-19 scenario, whereas, reaching the IA2030 targets reduces these proportions to 5% fewer FVPs and 5.22% more deaths. The impact of the disruption varies across the VPDs with diseases where coverage expands drastically in future years facing a smaller detrimental effect. Overall, our results show that drops in routine immunisation coverage could result in more deaths due to VPDs. As the impact of COVID-19-related disruptions is dependent on the vaccination coverage that is achieved over the coming years, the continued efforts of building up coverage and addressing gaps in immunity are vital in the road to recovery.


Assuntos
COVID-19 , Doenças Preveníveis por Vacina , COVID-19/prevenção & controle , Humanos , Imunização , Programas de Imunização , Vacinação/métodos , Doenças Preveníveis por Vacina/epidemiologia , Doenças Preveníveis por Vacina/prevenção & controle
20.
Trans R Soc Trop Med Hyg ; 115(3): 236-244, 2021 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-33515038

RESUMO

BACKGROUND: The 2030 goal for schistosomiasis is elimination as a public health problem (EPHP), with mass drug administration (MDA) of praziquantel to school-age children (SAC) as a central pillar of the strategy. However, due to coronavirus disease 2019, many mass treatment campaigns for schistosomiasis have been halted, with uncertain implications for the programmes. METHODS: We use mathematical modelling to explore how postponement of MDA and various mitigation strategies affect achievement of the EPHP goal for Schistosoma mansoni and S. haematobium. RESULTS: For both S. mansoni and S. haematobium in moderate- and some high-prevalence settings, the disruption may delay the goal by up to 2 y. In some high-prevalence settings, EPHP is not achievable with current strategies and so the disruption will not impact this. Here, increasing SAC coverage and treating adults can achieve the goal. The impact of MDA disruption and the appropriate mitigation strategy varies according to the baseline prevalence prior to treatment, the burden of infection in adults and the stage of the programme. CONCLUSIONS: Schistosomiasis MDA programmes in medium- and high-prevalence areas should restart as soon as is feasible and mitigation strategies may be required in some settings.


Assuntos
COVID-19/epidemiologia , Controle de Doenças Transmissíveis/organização & administração , Doenças Negligenciadas/epidemiologia , Doenças Negligenciadas/prevenção & controle , Esquistossomose/epidemiologia , Esquistossomose/prevenção & controle , Animais , Humanos , Administração Massiva de Medicamentos , Modelos Teóricos , Pandemias , Saúde Pública , SARS-CoV-2 , Schistosoma haematobium , Esquistossomose mansoni
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