Understanding small-scale COVID-19 transmission dynamics with the Granger causality test

Abstract

Mobility patterns have been broadly studied and deeply altered due to the coronavirus disease (COVID-19). In this paper, we study small-scale COVID-19 transmission dynamics in the city of Valencia and the potential role of subway stations and healthcare facilities in this transmission. A total of 2,398 adult patients were included in the analysis. We study the temporal evolution of the pandemic during the first six months at a small-area level. Two Voronoi segmentations of the city (based on the location of subway stations and healthcare facilities) have been considered, and we have applied the Granger causality test at the Voronoi cell level, considering both divisions of the study area. Considering the output of this approach, the so-called ‘donor stations’ are subway stations that have sent more connections than they have received and are mainly located in interchanger stations. The transmission in primary healthcare facilities showed a heterogeneous pattern. Given that subway interchange stations receive many cases from other regions of the city, implementing isolation measures in these areas might be beneficial for the reduction of transmission.

Keywords:

• COVID-19
• epidemiological dynamics
• functional networks
• modeling experiment
• public health crisis
• public transport
• Voronoi diagram

Availability of data and material

Data would be available under reasonable request and after the approval of the Institutional Review Board approval.

Code availability

The code is available under reasonable request.

Competing interests

The authors declare that they have no known competing financial interests or personal relationships that could influence the work reported in this paper.

Ethics approval/consent to participate

The study was approved by the institutional review board, and the requirement for informed consent was waived. Protocol code: COVID19-MAPA. Register number: 67/2020. NCT04581096

Role of the funder/sponsor

The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Additional information

Funding

This study was funded by the Innovation, University, Science and Digital Society Council through the Valencia Innovation Agency (AVI). This project also received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant No. 851255). M. Z. acknowledges the Spanish State Research Agency through the Severo Ochoa and María de Maeztu Program for Centers and Units of Excellence in Research and Development (MDM-2017-0711).