Selective and strategic lockdown of specific neighborhoods could aid in reducing SARS-CoV-2 transmission in cities

1. In this epidemiological cohort study based out of Valencia, Spain, the neighborhood where the hospital and COVID-19 testing facility was situated correlated with a high number of total infectious connections and was potentially a major contributor to local spread.

2. These findings suggest that a more selective and strategic lockdown of specific neighborhoods in cities could aid in reducing COVID-19 transmission.

Evidence Rating Level: 2 (Good)

Study Rundown: Valencia, the third most populated city in Spain, confirmed its first case of COVID-19 on February 19, 2020 and entered a citywide lockdown from March 14 to May 15, 2020. During this outbreak period, the city’s infection rate followed a heterogeneous distribution where the University General Hospital, the institution affiliated with this study, was designated as a COVID-19 center with a catchment area population of 364,000. Throughout, limited data was available on the spatial distribution and geographical characteristics of the transmission and dynamics of SARS-CoV-2 at the municipal level. This information is imperative when planning infection control measures and addressing local outbreaks. Thus, this epidemiological cohort study sought to describe the dynamics of SARS-CoV-2 transmission in Valencia by targeting specific neighborhoods and examining the local dissemination of infection during the initial 6 months of the pandemic. The main outcome of the analysis was the characterization of transmission distributions and connections between the 20 neighborhoods of Valencia during the outbreak. In order to recreate the transmission network, inbound and outbound connections were identified and closely monitored for each neighborhood, and the relative risk of infection in each region was estimated. In total, 2,646 patients from Valencia with a known COVID-19 diagnosis were included in the analysis where results showed an association between the neighborhood where the COVID-19 testing facility was situated and the total number of connections (both inbound and outbound). Furthermore, the mean income and population density had a direct correlation with the number of infectious cases in the region. These patterns of dissemination and distribution suggested that a more selective and strategic lockdown of specific neighborhoods in Valencia could have potentially aided in reducing the spread of SARS-CoV-2 in the city. A limitation of this study was that data was compiled from only one center in Valencia, likely decreasing its generalizability for public health planning in other locations.

Click to read the study in JAMA Network Open

Relevant Reading: Spatial and temporal dynamics of SARS-CoV-2 in COVID-19 patients: a systematic review and meta-analysis

In-Depth [retrospective cohort]: This single-center epidemiological cohort study of patients diagnosed with COVID-19 was performed at University General Hospital in Valencia, Spain. The study included 2,646 consecutive patients with COVID-19 isolated at home from February 19 to August 31, 2020. The mean (SD) age was 45.3 (22.5) years where 1,203 (46%) were male. The overall mortality rate of the cohort was 3.7%. Upon analysis, the incidence of COVID-19 was higher among 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 region where the hospital and COVID-19 testing facility was located (Neighborhood 3) had the most outbound connections (14). Furthermore, a large residential complex close to the city (neighborhood 20) registered the fewest number of connections (0 outbound and 2 inbound). Lastly, 5 geographically isolated neighborhoods were identified as strategically important in disrupting the transmission network among infected patients in the city.

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