Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exercise

Background During the COVID-19 pandemic, Santé publique France (SpF) published incidence (SpFi) rates based on census denominators. Denominators using cell phone connection (CPC) data can better reflect the population present and seasonal mobilities. Aim Given uncertainties regarding the actual numb...

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Main Author: Mohamed Hamidouche
Format: Article
Language:English
Published: European Centre for Disease Prevention and Control 2025-06-01
Series:Eurosurveillance
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Online Access:https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2025.30.22.2400530
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author Mohamed Hamidouche
author_facet Mohamed Hamidouche
author_sort Mohamed Hamidouche
collection DOAJ
description Background During the COVID-19 pandemic, Santé publique France (SpF) published incidence (SpFi) rates based on census denominators. Denominators using cell phone connection (CPC) data can better reflect the population present and seasonal mobilities. Aim Given uncertainties regarding the actual number of Île-de-France (IdF) residents present in IdF during summer 2021, we aimed to better approximate true incidence rates from positive SARS-CoV-2 tests in IdF using CPC-derived population denominators. Method This longitudinal study used the daily number of positive tests (PCR and Ag) on IdF residents in IdF as the numerator and the estimated resident population present in IdF at midnight as the denominator. We computed the mean corrected incidence rate (MCIR) per moving week between 4 July and 9 September 2021. Results The MCIR showed higher incidence rates than initially estimated, especially during August when residents had left IdF for the holidays. Incidence rates reached a peak on 16 August when the SpFi rate per moving week was 200.9 per 100,000 compared with 315.6 per 100,000 with the MCIR, representing a 57% increase. Conclusion Using local SARS-CoV-2 testing data and real-time population denominators, we showed that indicators using non-geographically referenced test results and fixed population denominators that ignore seasonal mobility can significantly underestimate incidence rates in IdF. New data sources using CPC data provide the opportunity to calculate more accurate and dynamic incidence rates and to map epidemics more precisely and in real time.
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spelling doaj-art-233f8446705449bcae7feed982f157bf2025-08-20T02:32:48ZengEuropean Centre for Disease Prevention and ControlEurosurveillance1560-79172025-06-01302210.2807/1560-7917.ES.2025.30.22.2400530http://instance.metastore.ingenta.com/content/eurosurveillance/30/22Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exerciseMohamed Hamidouche0https://orcid.org/0000-0002-5827-5395Direction des Régions, Santé Publique France, Saint-Maurice, FranceBackground During the COVID-19 pandemic, Santé publique France (SpF) published incidence (SpFi) rates based on census denominators. Denominators using cell phone connection (CPC) data can better reflect the population present and seasonal mobilities. Aim Given uncertainties regarding the actual number of Île-de-France (IdF) residents present in IdF during summer 2021, we aimed to better approximate true incidence rates from positive SARS-CoV-2 tests in IdF using CPC-derived population denominators. Method This longitudinal study used the daily number of positive tests (PCR and Ag) on IdF residents in IdF as the numerator and the estimated resident population present in IdF at midnight as the denominator. We computed the mean corrected incidence rate (MCIR) per moving week between 4 July and 9 September 2021. Results The MCIR showed higher incidence rates than initially estimated, especially during August when residents had left IdF for the holidays. Incidence rates reached a peak on 16 August when the SpFi rate per moving week was 200.9 per 100,000 compared with 315.6 per 100,000 with the MCIR, representing a 57% increase. Conclusion Using local SARS-CoV-2 testing data and real-time population denominators, we showed that indicators using non-geographically referenced test results and fixed population denominators that ignore seasonal mobility can significantly underestimate incidence rates in IdF. New data sources using CPC data provide the opportunity to calculate more accurate and dynamic incidence rates and to map epidemics more precisely and in real time.https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2025.30.22.2400530incidenceCovid-19mobile phoneratespopulationSARS-CoV-2
spellingShingle Mohamed Hamidouche
Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exercise
Eurosurveillance
incidence
Covid-19
mobile phone
rates
population
SARS-CoV-2
title Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exercise
title_full Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exercise
title_fullStr Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exercise
title_full_unstemmed Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exercise
title_short Use of cell phone data to correct Île-de-France population estimates and SARS-CoV-2 incidence, July to September, 2021: a proof-of-concept exercise
title_sort use of cell phone data to correct ile de france population estimates and sars cov 2 incidence july to september 2021 a proof of concept exercise
topic incidence
Covid-19
mobile phone
rates
population
SARS-CoV-2
url https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2025.30.22.2400530
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