Spatiotemporal Dynamics of COVID-19 Infections in Mainland Portugal

Abstract

The World Health Organization declared COVID-19 as a pandemic disease on 12 March 2020. Currently, this disease caused by the SARS-CoV-2 virus remains one of the biggest public health problems in the world. Thus, it is essential to apply methods that enable a better understanding of the virus diffusion processes, not only at the spatial level but also at the spatiotemporal one. To that end, we tried to understand the spatial distribution of COVID-19 pathology in continental Portugal at the municipal level and to comprehend how mobility influences transmission. We used autocorrelation indices such as Getis-Ord (with Euclidian distance and commuting values), Local Moran, and a new hybrid approach. Likewise, aiming to identify the spatiotemporal patterns of the virus propagation by using Man–Kendall statistics, we found that most hotspots of infected individuals occur in the municipalities of metropolitan areas. The spatiotemporal analysis identified most of the municipalities as oscillating hotspots.

Is a tiered restrictions system an effective intervention for COVID-19 control? Results from Portugal, November-December 2020

“…Additionally, the unequal testing capacity across the country [ 1 ] could have also skewed the true interpretation of COVID-19 infection rates. This may have contributed to the increase in the incidence rate observed at the end of the study period, which also influenced the tiers assignment since this was based on municipalities incidence.…”

“…This study had several limitations that might influence its interpretation. Unequal geographic testing capacity could have led to measurement bias since the likelihood of getting a positive case increase [ 1 ]. Additionally, individuals living in higher tiers might be more likely to get tested due to the higher risk of infection.…”

“…Portugal experienced the first wave of COVID-19 cases from March to June 2020 [ 1 ], with a national lockdown in place from 18th March to 3rd May [ 2 ], requiring citizens to stay at home except to access medical care, daily exercise, shopping for essentials, and essential work travel. September 2020 saw a resurgence of COVID-19 cases, with a rapid increase in the number of new cases, which coincided with the return to face-to-face work and school after the summer holidays [ 1 ]. This second wave was unevenly distributed across the country, with certain areas more severely affected than others, particularly in the metropolitan areas and their adjacent municipalities [ 1 ].…”

“…September 2020 saw a resurgence of COVID-19 cases, with a rapid increase in the number of new cases, which coincided with the return to face-to-face work and school after the summer holidays [ 1 ]. This second wave was unevenly distributed across the country, with certain areas more severely affected than others, particularly in the metropolitan areas and their adjacent municipalities [ 1 ].…”

Introductory Chapter: GIS and Spatial Analysis

“…In the health field, GIS can be used to map disease incidence and prevalence rates, identify patterns and clusters of diseases [1], and assess the impact of environmental factors on health outcomes [2]. For example, GIS can be used to identify areas with high rates of cancer and investigate whether there are any environmental factors, such as air pollution or water contamination, which may be contributing to the high incidence rates [3][4][5].…”