Serosurveillance for vaccine-preventable diseases: A look inside the pertussis experience / Serovigilancia de enfermedades prevenibles por vacunación: una mirada desde la experiencia con la tosferina

INTRODUCTION: Serological surveillance (serosurveillance) provides the most direct measure of herd immunity of vaccine-preventable diseases. Little is known about the opportunities and challenges of serosurveillance experiences, particularly pertussis. OBJECTIVE: To describe the process of serosurveillance for vaccine-preventable diseases with an emphasis on the experience of pertussis in the metropolitan area of Antioquia (Valle de Aburrá) in 2015 and 2016 and analyze the contributions and challenges for its sustainability. MATERIALS AND METHODS: We described the planning and conduction of serosurveillance of pertussis antibodies of mothers and in the umbilical cord at the time of delivery in eight hospitals based on random sampling and their capacity to advance the serosurveillance periodically. We compared the contributions and the challenges of this experience with other probabilistic and non-probabilistic programs. RESULTS: We achieved the participation of hospitals and mothers respecting the delivery care process. We established a serum bank following ethical and technical guidelines. This program based on the random selection of hospitals and mothers has enabled the estimation of antibodies prevalence in mothers and in the umbilical cord, which has been possible given the high coverage of hospital care during childbirth at a lower cost and fewer risks than a population-based survey in conflictive areas. The main challenges for the sustainability of this program are the creation of stable jobs and access to funding and legal and methodological long-term frameworks. CONCLUSIONS: Hospital serosurveillance as described is an option to monitor the impact of vaccination on the population. Our experience could be reproduced in other regions under similar conditions if the above-mentioned challenges are solved.

Introducción. La vigilancia serológica es la forma más directa de medir la inmunidad de rebaño frente a las enfermedades prevenibles por vacunación. Poco se sabe acerca de las oportunidades y los desafíos de las experiencias de serovigilancia, en general y, específicamente, la de la tosferina.Objetivo. Describir el proceso de serovigilancia de enfermedades prevenibles por vacunación con énfasis en la experiencia en el caso de la tosferina en el área metropolitana de Antioquia (Valle de Aburrá) en el 2015 y el 2016 y analizar lo que dicha experiencia ha aportado y los desafíos que persisten para su sostenibilidad.Materiales y métodos. Se describió el proceso de planeación y el desarrollo de la serovigilancia de tosferina en el momento del parto en ocho hospitales seleccionados al azar, así como la capacidad para adelantar el programa de manera periódica. Se compararon los aportes y los desafíos en el curso de esta experiencia con los de otros programas poblacionales probabilistas e institucionales no probabilistas.Resultados. Se logró la participación de los hospitales y de las madres con pleno respeto del proceso de atención del parto, y se conformó un banco de sueros siguiendo lineamientos éticos y técnicos. El programa permitió estimar la prevalencia de anticuerpos en la madre y en el cordón umbilical, lo que se facilitó por la alta cobertura de atención hospitalaria del parto, a un menor costo y menos riesgos que los programas poblacionales en zonas conflictivas. Los principales desafíos para la sostenibilidad del programa son la estabilidad laboral del personal de salud, así como normas y una financiación de largo plazo.Conclusiones. La serovigilancia hospitalaria es una opción para monitorizar el impacto poblacional de la vacunación. Esta experiencia se podría extender a otras regiones en condiciones similares si se resuelven los retos mencionados.

Algebraic analysis of social networks for bio-surveillance: the cases of SARS-Beijing-2003 and AH1N1 influenza-México-2009.

Algebraic analysis of social networks exhibited by SARS-Beijing-2003 and AH1N1 flu-México-2009 was realized. The main tools were the Tutte polynomials and Maple package Graph-Theory. The topological structures like graphs and networks were represented by invariant polynomials. The evolution of a given social network was represented like an evolution of the algebraic complexity of the corresponding Tutte polynomial. The reduction of a given social network was described like an involution of the algebraic complexity of the associated Tutte polynomial. The outbreaks of SARS and AH1N1 Flu were considered like represented by a reduction of previously existing contact networks via the control measures executed by health authorities. From Tutte polynomials were derived numerical indicators about efficiency of control measures.

[Modelling epidemics: the case of severe acute respiratory syndrome in Canada]. / Bases para la Modelación de Epidemias: el Caso del Síndrome Respiratorio Agudo Severo en Canadá

OBJECTIVE: Severe acute respiratory syndrome propagation in Canada during 2003 is analysed by means of simple models, comparing the influence of isolation measures on two epidemic waves. METHODS: Deterministic susceptible-infected and susceptible-infected-removed models were used for both epidemic waves, using official published information. NLREG 6.2 was used for estimating deterministic parameters and analytical solutions were obtained with Maple 9 software. Dynamical indicators were obtained for the epidemic. RESULTS: Suitable adjustment of the data was observed with both models, but smaller adjustment was observed during the second wave with the non- removed model. The highest rate of infectiousness was shown (35 new cases per 10 000 susceptible people) during the second wave (with R0 near to one), in spite of presenting greater incidence (8.8 cases per day), compensated for by a high rate of removal (11,5 cases per day) which lasted less than the epidemic (11,1 days), and a lower rate of attack (1 case per each 100 susceptible people). CONCLUSIONS: The susceptible-infected model can be useful during an epidemic's initial phase (prior to removal); however, closer monitoring of an epidemic's development is required for modelling the strength of removal and deriving useful information for decision-making.

Bases para la Modelación de Epidemias: el Caso del Síndrome Respiratorio Agudo Severo en Canadá / Modelling epidemics: the case of severe acute respiratory syndrome in Canada

Objetivo: Se ilustra el análisis de la propagación del síndrome respiratorio agudo severo en Canadá en 2003, mediante modelos simples, comparando la influencia de las medidas de aislamiento en dos ondas epidémicas. Métodos: Se utilizan los modelos Susceptible-Infectado y Susceptible- Infectado-Removido en versión determinista para ambas ondas epidémicas, utilizando información oficial publicada. Se estiman los parámetros deterministas con el programa NLREG 6,2 y se obtienen soluciones analíticas con Maple 9. Se obtienen indicadores para el análisis de la dinámica de la epidemia. Resultados: Se observó un adecuado ajuste de los datos con ambos modelos pero en la segunda onda se observó un menor ajuste con el modelo sin remoción. En la segunda onda, con un R0 ligeramente menor a 1, a pesar de presentar la mayor incidencia (8,8 casos por día), se tuvo el más alto ritmo de infección (35 caso nuevos por 10 000 susceptibles) compensado con un alto ritmo de remoción (11,5 casos por día), lo que llevó a una menor duración de la epidemia (11,1 días) y una menor tasa de ataque (1 caso por cada cien susceptibles). Conclusiones: El modelo susceptible - infectado puede ser útil en la fase inicial de la epidemia, previo a la instauración de la remoción pero se requiere una vigilancia estrecha de la evolución de la epidemia para incorporar la modelación de la fuerza de remoción y derivar información que sustente las decisiones.

Objective: Severe acute respiratory syndrome propagation in Canada during 2003 is analysed by means of simple models, comparing the influence of isolation measures on two epidemic waves. Methods: Deterministic susceptible-infected and susceptible-infected-removed models were used for both epidemic waves, using official published information. NLREG 6.2 was used for estimating deterministic parameters and analytical solutions were obtained with Maple 9 software. Dynamical indicators were obtained for the epidemic. Results: Suitable adjustment of the data was observed with both models, but smaller adjustment was observed during the second wave with the non- removed model. The highest rate of infectiousness was shown (35 new cases per 10 000 susceptible people) during the second wave (with R0 near to one), in spite of presenting greater incidence (8.8 cases per day), compensated for by a high rate of removal (11,5 cases per day) which lasted less than the epidemic (11,1 days), and a lower rate of attack (1 case per each 100 susceptible people). Conclusions: The susceptible-infected model can be useful during an epidemic's initial phase (prior to removal); however, closer monitoring of an epidemic's development is required for modelling the strength of removal and deriving useful information for decision-making.

Tuberculosis control and managed competition in Colombia.

Law 100 introduced the Health Sector Reform in Colombia, a model of managed competition. This article addresses the effects of this model in terms of output and outcomes of TB control. Trends in main TB control indicators were analysed using secondary data sources, and 25 interviews were done with key informants from public and private insurers and provider institutions, and from the health directorate level. We found a deterioration in the performance of TB control: a decreasing number of BCG vaccine doses applied, a reduction in case finding and contacts identification, low cure rates and an increasing loss of follow up, which mainly affects poor people. Fragmentation occurred as the atomization and discontinuity of the technical processes took place, there was a lack of coordination, as well as a breakdown between individual and collective interventions, and the health information system began to disintegrate. The introduction of the Managed Competition (MC) in Colombia appeared to have adverse effects on TB control due to the dominance of the economic rationality in the health system and the weak state stewardship. Our recommendations are to restructure the reform's public health component, strengthen the technical capacity in public health of the state, mainly at the local and departmental levels, and to improve the health information system by reorienting its objectives to public health goals.