Browsing by Author "Apablaza, Mauricio"

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    Gallbladder cancer mortality in Chile: Has the government program targeting young gallstone patients had an impact?
    (2024) Cid, Vicente; Vargas, Claudio; Delgado, Iris; Apablaza, Mauricio; Shiels, Meredith S.; Hildesheim, Allan; Koshiol, Jill; Ferreccio, Catterina
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    Overcoming Health Inequities: Spatial Analysis of Seroprevalence and Vaccination Against COVID-19 in Chile
    (2024) Ramirez-Santana, Muriel; Correa, Juan; Franz, Loreto Nunez; Apablaza, Mauricio; Rubilar, Paola; Vial, Cecilia; Cortes, Lina Jimena; Hormazabal, Juan; Canales, Luis; Vial, Pablo; Aguilera, Ximena
    Background: In unequal economies, the spread of the first waves of the COVID-19 was usually associated with low socioeconomic status of individuals and their families. Chile exemplified this. By mid-2020, Chile had one of the highest SARS-CoV-2 infection rates in the world predominantly in poorer areas. A year later, the country launched a universal vaccination campaign based on the national strategy of immunization established in 1975. By 2022, Chile presented one of the highest COVID-19 vaccination coverages globally, reaching 94.3% of the population with the primary scheme by the end of 2022.Objective: This study analyzes the spatial distribution of SARS-CoV-2 seroprevalence at the beginning of the pandemic (2020) compared with the seroprevalence after 2 years of ongoing epidemic and COVID-19 vaccination campaigns (2022).Methods: Two population-based random samples of individuals aged 7 years and older from two Chilean cities were studied. Utilizing an enzyme-linked immunosorbent assay test, IgG antibodies were measured in serum of 1061 participants in 2020, and 853 in 2022.Results: Using the Global Moran's Index, the seroprevalence distribution pattern for the year 2020 showed clustering in the two cities. Conversely, seroprevalence and vaccinations were homogeneously distributed in 2022. These results show the success of the vaccination campaign in Chile, not only in coverage but also because it widely reached all individuals.Conclusions: The uptake of this preventive measure is high, regardless of the social and economic factors, achieving broad population immunity. The extensive deployment of the primary health care network contributed to reducing health inequities and promoting to universal health access.
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    Population-based seroprevalence survey: post-pandemic COVID-19 vaccination, related factors, and geographic distribution of vaccine acceptability in Chile
    (2025) Nuñez-Franz, Loreto; Rubilar, Paola; Apablaza, Mauricio; Canales, Luis; Cortés, Lina J.; Molina, Xaviera; Said, Macarena; Olivares, Kathya; Correa Parra, Juan; Ramírez-Santana, Muriel
    Background Prevention of infectious diseases is based on host protection, especially using vaccines. Several factors have been linked to the acceptance of vaccines in the population. Chile achieved high COVID-19 vaccination coverage early in the pandemic. The study aimed to determine the prevalence of antigens and antibodies, vaccination status, geographical distribution, and factors related to vaccine acceptability. Methods In two Chilean cities, the fourth round of a population-based seroprevalence cross-sectional survey was conducted in May 2024. 654 participants aged seven or older were recruited. After signing consent, participants were interviewed, blood samples were taken to identify antibodies against SARS-CoV-2 using ELISA, and antigens were assessed through a nasal swab rapid test. Territorial analysis of the vaccine dose distribution was carried out. Results All participants tested negative for antigens and positive for antibodies against SARS-CoV-2, with an overall vaccination uptake rate of 98,5%. However, their vaccination status was heterogeneous. Territorial distribution showed a slight geographical clustering of vaccine doses in both cities. 52.7% had the basic scheme and/or boosters, 32.1% had the bivalent vaccine, and 13.7% had anti-Omicron. Self-report identification with a risk group was not associated with vaccine adherence. City, age, education, and comorbidities were associated with perceived and actual risk discrepancies. Conclusions Overall, vaccine acceptance is high. However, the acceptance of the last two doses was below expectations and showed heterogeneous geographical distribution. Adulthood is the most important predictor of vaccine uptake. Participants underestimated their level of risk. Risk communication must be improved, especially for risk groups, to help them perceive themselves as beneficiaries of vaccination. Efforts should be made to disseminate information on vaccine safety and counter misinformation to increase knowledge about vaccines.