Assuntos
Vacinas contra Dengue , Dengue , Programas de Imunização , Humanos , Brasil/epidemiologia , Dengue/epidemiologia , Dengue/imunologia , Dengue/prevenção & controle , Dengue/virologia , Vacinas contra Dengue/administração & dosagem , Vacinas contra Dengue/imunologia , Vacinas contra Dengue/provisão & distribuição , Vírus da Dengue/imunologiaRESUMO
BACKGROUND: Dengue fever has been a major public health concern in Colombia, Thailand, and Vietnam. Unlike other infectious diseases, dengue vaccines had not been available for a long time, causing difficulties to control the disease. However, the first live attenuated, tetravalent dengue vaccine (CYD-TDV) became available in 2016 and has been already licensed in some dengue-endemic countries. Because several second-generation dengue vaccines are also in the pipeline, it is critical to understand the efficient allocation of dengue vaccines considering the geographical variation of the disease. METHODS: The Climate Risk Factor (CRF) index was created using the climate and non-climate factors in the three countries. A random-coefficient negative binomial model was chosen to validate the relationship between the CRF index and dengue incidence proxy. Given the statistical significance of the CRF index, high risk areas for dengue fever were identified at the 5â¯km by 5â¯km resolution and used to estimate vaccination coverage rates and the number of doses required for various types of vaccination scenarios by country. RESULTS AND CONCLUSIONS: Based upon a three-dose scheme, the estimated number of vaccines required for routine vaccination targeting 9 years old ranged from 1 to 2.6 million doses across the countries during the first year of introduction. A one-off catch-up campaign targeting the age group of 10-17 year olds would require 8 to 18 million additional doses. Routine vaccination (with or without a catch-up campaign) covered 63%, 90%, and 91% of the targeted age group populations in Colombia, Thailand, and Vietnam respectively. Given that many dengue-endemic countries face limited resources and that the costs for mass vaccination campaigns may not be trivial, the findings of this study can guide the decision makers in the three countries regarding the efficient distribution of vaccines by identifying populations at high risk at 5â¯km by 5â¯km resolution.
Assuntos
Vacinas contra Dengue/provisão & distribuição , Dengue/prevenção & controle , Adolescente , Adulto , Criança , Clima , Colômbia/epidemiologia , Dengue/epidemiologia , Doenças Endêmicas , Epidemias , Feminino , Humanos , Masculino , Tailândia/epidemiologia , Vietnã/epidemiologia , Adulto JovemRESUMO
Dengue is endemic in Brazil. Several dengue vaccine candidates, including one at the Butantan Institute in Sao Paulo, are being evaluated in clinical trials and may be licensed in several years. This study estimates the potential doses of dengue vaccine needed in Brazil under different scenarios in the first 5 years after vaccine introduction. Estimates were based on 2015-2022 country population projections. An estimated country population of 200-209 million with an annual 3.3-3.5 million cohort in the 12 to 23 month age group was included in the analysis. Computations were made for vaccines requiring one, two and three doses. A total of 7.8-62.9 million doses would be needed for only routine vaccination of 12-23 months cohort in first five years with different vaccination schedules. A combination of country-wide routine 12-23 month-old vaccination plus catch-up vaccination of individuals up to 40 years age is an appropriate strategy to control dengue. For this combination strategy, 129-425 million doses would be needed in the first five years after introduction. If vaccination is not provided to areas with low incidence of dengue, an estimated 108-360 million doses would be needed. This study provides a range of vaccine uptake estimates under different scenarios based on disease epidemiology. Actual demand and uptake will depend on the country vaccine introduction policy and strategies, vaccine supply capacity, cost, and vaccine profile. We consider one option based on the availability of vaccine from different sources. A more advanced vaccine uptake model based on estimates of vaccine impact under various scenarios should be developed.