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Author: search.filters.author.Eduardo A. UndurragaSubject: search.filters.subject.epidemic

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    Transmission dynamics and control of COVID-19 in Chile, March-October, 2020
    (2021)
    Amna Tariq
    ;
    Eduardo A. Undurraga
    ;
    CASTILLO LABORDE, CARLA CECILIA  
    ;
    Katia Vogt-Geisse
    ;
    Ruiyan Luo
    <jats:p>Since the detection of the first case of COVID-19 in Chile on March 3<jats:sup>rd</jats:sup>, 2020, a total of 513,188 cases, including ~14,302 deaths have been reported in Chile as of November 2<jats:sup>nd</jats:sup>, 2020. Here, we estimate the reproduction number throughout the epidemic in Chile and study the effectiveness of control interventions especially the effectiveness of lockdowns by conducting short-term forecasts based on the early transmission dynamics of COVID-19. Chile’s incidence curve displays early sub-exponential growth dynamics with the deceleration of growth parameter,<jats:italic>p</jats:italic>, estimated at 0.8 (95% CI: 0.7, 0.8) and the reproduction number,<jats:italic>R</jats:italic>, estimated at 1.8 (95% CI: 1.6, 1.9). Our findings indicate that the control measures at the start of the epidemic significantly slowed down the spread of the virus. However, the relaxation of restrictions and spread of the virus in low-income neighborhoods in May led to a new surge of infections, followed by the reimposition of lockdowns in Greater Santiago and other municipalities. These measures have decelerated the virus spread with<jats:italic>R</jats:italic>estimated at ~0.96 (95% CI: 0.95, 0.98) as of November 2<jats:sup>nd</jats:sup>, 2020. The early sub-exponential growth trend (<jats:italic>p</jats:italic>~0.8) of the COVID-19 epidemic transformed into a linear growth trend (<jats:italic>p</jats:italic>~0.5) as of July 7<jats:sup>th</jats:sup>, 2020, after the reimposition of lockdowns. While the broad scale social distancing interventions have slowed the virus spread, the number of new COVID-19 cases continue to accrue, underscoring the need for persistent social distancing and active case detection and isolation efforts to maintain the epidemic under control.</jats:p>
    Scopus© Citations 45  1
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    Effectiveness of CoronaVac in children 3–5 years of age during the SARS-CoV-2 Omicron outbreak in Chile
    (2022)
    Alejandro Jara
    ;
    Eduardo A. Undurraga
    ;
    José R. Zubizarreta
    ;
    Cecilia González
    ;
    Acevedo, Johanna
    <jats:title>Abstract</jats:title><jats:p>The outbreak of the B.1.1.529 lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Omicron) has caused an unprecedented number of Coronavirus Disease 2019 (COVID-19) cases, including pediatric hospital admissions. Policymakers urgently need evidence of vaccine effectiveness in children to balance the costs and benefits of vaccination campaigns, but, to date, the evidence is sparse. Leveraging a population-based cohort in Chile of 490,694 children aged 3–5 years, we estimated the effectiveness of administering a two-dose schedule, 28 days apart, of Sinovac’s inactivated SARS-CoV-2 vaccine (CoronaVac). We used inverse probability-weighted survival regression models to estimate hazard ratios of symptomatic COVID-19, hospitalization and admission to an intensive care unit (ICU) for children with complete immunization over non-vaccination, accounting for time-varying vaccination exposure and relevant confounders. The study was conducted between 6 December 2021 and 26 February 2022, during the Omicron outbreak in Chile. The estimated vaccine effectiveness was 38.2% (95% confidence interval (CI), 36.5–39.9) against symptomatic COVID-19, 64.6% (95% CI, 49.6–75.2) against hospitalization and 69.0% (95% CI, 18.6–88.2) against ICU admission. The effectiveness against symptomatic COVID-19 was modest; however, protection against severe disease was high. These results support vaccination of children aged 3–5 years to prevent severe illness and associated complications and highlight the importance of maintaining layered protections against SARS-CoV-2 infection.</jats:p>
    Scopus© Citations 82  8