Browsing by Author "Canales, Luis"
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Publication Overcoming Health Inequities: Spatial Analysis of Seroprevalence and Vaccination Against COVID-19 in Chile(2024) Muriel Ramírez-Santana , Juan Hormazábal, Luis Canales, Pablo Vial, and Ximena Aguilera; Correa, Juan; Núñez Franz, Loreto; Apablaza, Mauricio; Rubilar, Paola; Vial Cox, María Cecilia; Cortes, Lina Jimena; Hormazabal, Juan; Canales, Luis; Vial, Pablo; Aguilera, XimenaBackground: In unequal economies, the spread of the first waves of the COVID-19 was usually associated withlow socioeconomic status of individuals and their families. Chile exemplified this. By mid-2020, Chile had one ofthe highest SARS-CoV-2 infection rates in the world predominantly in poorer areas. A year later, the countrylaunched a universal vaccination campaign based on the national strategy of immunization established in1975. 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 pan-demic (2020) compared with the seroprevalence after 2 years of ongoing epidemic and COVID-19 vaccinationcampaigns (2022).Methods: Two population-based random samples of individuals aged 7 years and older from two Chilean citieswere studied. Utilizing an enzyme-linked immunosorbent assay test, IgG antibodies were measured in serum of1061 participants in 2020, and 853 in 2022.Results: Using the Global Moran’s Index, the seroprevalence distribution pattern for the year 2020 showed clus-tering 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 itwidely 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 contrib-uted to reducing health inequities and promoting to universal health access.Publication Preventive behaviors for COVID-19 in Chile: Lessons from a population follow-up for 2021 and 2022(2024) Rubilar, Paola; Núñez-Franz, Loreto; Apablaza, Mauricio; Ramírez-Santana, Muriel; Molina, Xaviera; Canales, LuisINTRODUCTION The rapid emergence of COVID-19 urged policy responses worldwide, focusing on vaccination and mobility restrictions. Chile represents a unique scenario for analyzing personal preventive measures amid intensive communication and vaccination campaigns. This study aims to explore changes in population adherence to non-pharmacological preventive measures during the pandemic and the factors that explain this adherence each year. METHODS 386 individuals who participated in two population-based studies (2021 and 2022) were considered. An interview was conducted to measure adherence to self-care practices, and case and contact tracing by the health authorities. The Wilcoxon signedrank test was performed to measure change between 2021 and 2022, bivariate analysis, and a linear regression model for each year were performed. RESULTS Mask-wearing in public places was the most commonly used measure (95.9% in 2021, 89.9% in 2022). Follow-up of cases and cases contacts by the health authority had high coverage in 2021 (94.3% and 83% respectively). A greater decrease was observed in contact tracing in 2022 totaling 33.3%. An increase in the score of adherence to preventive practices was observed in 2022 (p < 0.00). The regression model showed in 2021 that women were more likely to adopt preventive behaviors (95% confidence interval: 0.27 to 1.13) and the overweight/obese had higher adherence compared to normal body mass index (95% confidence interval: 0.06 to 0.98). In 2022 being a young adult (30 to 49 years) predicted the adoption of behavioral precautions (95% confidence interval: 0.00 to 1.32). CONCLUSIONS Adherence to preventive measures increased even with high vaccination coverage, likely due to the epidemiological situation with the Omicron variant circulating in 2022.Item Seroprevalence of Natural and Acquired Immunity against the SARS-CoV-2 Virus in a Population Cohort from Two Chilean Cities, 2020–2022(2023) Núñez-Franz, Loreto; Ramírez-Santana, Muriel; Rubilar, Paola; Vial, Cecilia; Apablaza, Mauricio; González, Claudia; Said, Macarena; Olivares, Kathya; Cortés, Lina Jimena; Hormazábal, Juan; Canales, Luis; Vial, Pablo; Icaza, Gloria; Quezada-Gaete, Rubén; Aguilera, XimenaBackground: Chile has achieved the highest coverage for vaccines against the SARS-CoV-2 virus worldwide. Objective: To assess the progression of immunity (natural and acquired by vaccine) in a cohort from two Chilean cities. Methods: Individuals (n = 386) who participated in three phases of population-based serial prevalence studies were included (2020–2021 and 2022). Presence of SARS-CoV-2 antibodies was measured in serum. Data including time of vaccination and type of vaccine received were analysed with descriptive statistics. Results: Seroprevalence was 3.6% in the first round and increased to 96.9% in the second and 98.7% in the third. In the third round, 75% of individuals who had received the basal full scheme were seropositive at 180 days or more since their last dose; 98% of individuals who received one booster dose were seropositive at 180 days or more, and 100% participants who received two boosters were seropositive, regardless of time since their last dose. Participants receiving mRNA vaccines had higher seroprevalence rates over time. Conclusions: The high vaccination coverage in Chile enabled the population to maintain high levels of antibodies. Vaccination boosters are essential to maintain immunity over time, which also depends on the type of vaccine administered.