Background
Clinical trials and individual-level observational data in Israel demonstrated approximately 95% effectiveness of mRNA-based vaccines against symptomatic SARS-CoV-2 infection. Individual-level data are not available in many countries, particularly low- and middle- income countries. Using a novel Poisson regression model, we analyzed ecologic data in Costa Rica to estimate vaccine effectiveness and assess the usefulness of this approach.
Methods
We used national data from December 1, 2020 to May 13, 2021 to ascertain incidence, hospitalizations and deaths within ecologic units defined by 14 age groups, gender, 105 geographic areas, and day of the epidemic. Within each unit we used the proportions of the population with one and with two vaccinations, primarily tozinameran. Using a non-standard Poisson regression model that included an ecologic-unit-specific rate factor to describe rates without vaccination and a factor that depended on vaccine effectiveness parameters and proportions vaccinated, we estimated vaccine effectiveness.
Results
In 3.621 million persons aged 20 or older, there were 125,031 incident cases, 7716 hospitalizations, and 1929 deaths following SARS-CoV-2 diagnosis; 73% of those aged ≥ 75 years received two doses. For one dose, estimated effectiveness was 59% (95% confidence interval 53% to 64%) for SARS-CoV-2 incidence, 76% (68% to 85%) for hospitalizations, and 63% (47% to 80%) for deaths. For two doses, the respective estimates of effectiveness were 93% (90% to 96%), 100% (97% to 100%), and 100% (97% to 100%).
Conclusions
These effectiveness estimates agree well with findings from clinical trials and individual-level observational studies and indicate high effectiveness in the general population of Costa Rica. This novel statistical approach is promising for countries where ecologic, but not individual-level, data are available. The method could also be adapted to monitor vaccine effectiveness over calendar time.
Objetivo: identificar factores asociados al conocimiento sobre el tabaco y los riesgos de suconsumo basados en la “Encuesta global de tabaquismo en adultos” realizada en Costa Ricadurante el 2015.
Métodos: estudio epidemiológico, observacional de tipo transversal con representación nacional (n = 8 607). Con la base de datos de la “Encuesta global de tabaquismo en adultos”, se diseñó un modelo de ecuaciones estructurales y se construyó la variable latente: conocimientos.Como determinantes del conocimiento se usaron las variables: sociodemográficas, económicas,fumado, cesación, exposición a la publicidad y a la información sobre los peligros de fumar incluidas en la encuesta.
Resultados: el conocimiento sobre el tabaco y los riesgos del consumo aumentó con la edad,fue superior en hombres y en zonas urbanas. Los fumadores tuvieron menos conocimientossobre el fumado pasivo y más sobre enfermedades.
Conclusiones: la Encuesta global de tabaquismo en adultos permitió medir el nivelde conocimiento sobre los riesgos asociados al tabaco y estudiar sus determinantessocioeconómicos.
El análisis de inequidades sociales en salud es un proceso complejo y diverso que puede realizarse desde distintas aproximaciones epistémicas, teóricas y metodológicas. A partir de una amplia revisión documental y con el objetivo de facilitar este tipo de análisis, el presente artículo propone algunas recomendaciones metodológicas (en términos amplios) para la investigación de las inequidades sociales en salud.
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