Abstract
Limited information on the transmission and dynamics of SARS-CoV-2 at the city scale is available. To describe the local spread of SARS-CoV-2 in Valencia, Spain. This single-center epidemiological cohort study of patients with SARS-CoV-2 was performed at University General Hospital in Valencia (population in the hospital catchment area, 364 000), a tertiary hospital. The study included all consecutive patients with COVID-19 isolated at home from the start of the COVID-19 pandemic on February 19 until August 31, 2020. Cases of SARS-CoV-2 infection confirmed by the presence of IgM antibodies or a positive polymerase chain reaction test result on a nasopharyngeal swab were included. Cases in which patients with negative laboratory results met diagnostic and clinical criteria were also included. The primary outcome was the characterization of dissemination patterns and connections among the 20 neighborhoods of Valencia during the outbreak. To recreate the transmission network, the inbound and outbound connections were studied for each region, and the relative risk of infection was estimated. In total, 2646 patients were included in the analysis. The mean (SD) age was 45.3 (22.5) years; 1203 (46%) were male and 1442 (54%) were female (data were missing for 1); and the overall mortality was 3.7%. The incidence of SARS-CoV-2 cases was higher in neighborhoods with higher household income (β2 [for mean income per household] = 0.197; 95% CI, 0.057-0.351) and greater population density (β1 [inhabitants per km2] = 0.228; 95% CI, 0.085-0.387). Correlations with meteorological variables were not statistically significant. Neighborhood 3, where the hospital and testing facility were located, had the most outbound connections (14). A large residential complex close to the city (neighborhood 20) had the fewest connections (0 outbound and 2 inbound). Five geographically unconnected neighborhoods were of strategic importance in disrupting the transmission network. This study of local dissemination of SARS-COV-2 revealed nonevident transmission patterns between geographically unconnected areas. The results suggest that tailor-made containment measures could reduce transmission and that hospitals, including testing facilities, play a crucial role in disease transmission. Consequently, the local dynamics of SARS-CoV-2 spread might inform the strategic lockdown of specific neighborhoods to stop the contagion and avoid a citywide lockdown.
Highlights
Some studies have described SARS-CoV-2 transmission using online public data,[1,2,3,4,5] but limited information describes local COVID-19 transmission
The incidence of SARS-CoV-2 cases was higher in neighborhoods with higher household income (β2 [for mean income per household] = 0.197; 95% CI, 0.057-0.351) and greater population density (β1 [inhabitants per km2] = 0.228; 95% CI, 0.085-0.387)
The local dynamics of SARSCoV-2 spread might inform the strategic lockdown of specific neighborhoods to stop the contagion and avoid a citywide lockdown
Summary
Some studies have described SARS-CoV-2 transmission using online public data,[1,2,3,4,5] but limited information describes local COVID-19 transmission. The city’s infection rate followed a heterogeneous distribution during the outbreak, and our institution, the University General Hospital, was designated as a COVID-19 center. Knowledge of the spatial distribution and geographical characteristics is paramount to plan infection control measures and address local outbreaks. This study aimed to define the dynamics of SARS-CoV-2 transmission by targeting specific regions in the city of Valencia. We examined the local dissemination of SARS-CoV-2 during the first 6 months of the pandemic, considering the first sequentially diagnosed patients in 20 neighborhoods of the city
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