Detection of SARS-CoV-2 RNA in wastewater and importance of population size assessment in smaller cities: An exploratory case study from two municipalities in Latvia

Wastewater-based epidemiology (WBE) has regained global importance during the COVID-19 pandemic. The mobility of people and other factors, such as precipitation and irregular inflow of industrial wastewater, are complicating the estimation of the disease prevalence through WBE, which is crucial for proper crisis management. These estimations are particularly challenging in urban areas with moderate or low numbers of inhabitants in situations where movement restrictions are not adopted (as in the case of Latvia) because residents of smaller municipalities tend to be more mobile and less strict in following the rules and measures of disease containment. Thus, population movement can influence the outcome of WBE measurements significantly and may not reflect the actual epidemiological situation in the respective area. Here, we demonstrate that by combining the data of detected SARS-CoV-2 RNA copy number, 5-hydroxyindoleacetic acid (5-HIAA) analyses in wastewater and mobile call detail records it was possible to provide an accurate assessment of the COVID-19 epidemiological situation in towns that are small (COVID-19 28-day cumulative incidence r = 0.609 and 35-day cumulative incidence r = 0.89, p < 0.05) and medium-sized towns (COVID-19 21-day cumulative incidence r = 0.997, 28-day cumulative incidence r = 0.98 and 35-day cumulative incidence r = 0.997, p < 0.05). This is the first study demonstrating WBE for monitoring COVID-19 outbreaks in Latvia. We demonstrate that the application of population size estimation measurements such as total 5-HIAA and call detail record data improve the accuracy of the WBE approach.

Socio-Economic Situation in Latvia's Municipalities in the Context of Administrative-Territorial Division and Unexpected Impact of COVID-19

In this research, the authors analysed how the behaviour of people changed in various phases of the COVID-19 pandemic and how these changes affected the economic activity in municipalities, taking into consideration significant changes in people’s habits and employment conditions. The pandemic coincided with the administrative-territorial reform in Latvia, providing a unique opportunity to test and ascertain in a single research both the above-mentioned changes in the economic activity of inhabitants and the viability of the new administrative-territorial division vis-a-vis the new reality. The developed regional planning methodology based on the mobile phone activity data and socio-economic indicators (set of indicators provided by regional development state institutions) is used to categorize the 43 newly formed municipalities into similar groups. It is concluded that the aggregated indicators have a significant impact on the division of municipalities: Inhabitants, Dynamics indicator, Economic development level, Mobile phone activity on workdays, holidays and weekends.