Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jun;30(22):2400530.
doi: 10.2807/1560-7917.ES.2025.30.22.2400530.

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

Arnaud Tarantola  1 , Mohamed Hamidouche  1
Affiliations

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

Arnaud Tarantola et al. Euro Surveill. 2025 Jun.

Abstract

BackgroundDuring 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.AimGiven 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.MethodThis 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.ResultsThe 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.ConclusionUsing 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.

Keywords: Covid-19; SARS-CoV-2; cell phone; epidemic; epidemiology; incidence; mobile phone; population; rates.

PubMed Disclaimer

Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Overview of mean official (SpFi) incidence rate per moving week and mean corrected incidence rate (MCIR) per moving week, Île-de-France, 4 July–9 September 2021
Figure 2
Figure 2
SpF and corrected SARS-CoV-2 incidence by moving week, Île-de-France, 28 June–9 September 2021a
Figure 3
Figure 3
Impact of discrepancies between official SpF data (A) and corrected data (B) on estimated real-time Reff values of SARS-CoV-2 cases among Île-de-France residents, 28 June–9 September 2021a
See this image and copyright information in PMC

References

    1. Connor H. John Graunt F.R.S. (1620-74): The founding father of human demography, epidemiology and vital statistics. J Med Biogr. 2024;32(1):57-69. 10.1177/09677720221079826 - DOI - PMC - PubMed
    1. Bhopal RS. The epidemiological concept of population. In: Bhopal RS, editor. Concepts of Epidemiology: Integrating the ideas, theories, principles, and methods of epidemiology. Oxford University Press; 2016. Available from: 10.1093/med/9780198739685.003.0002 - DOI
    1. Amodio E, Zarcone M, Casuccio A, Vitale F. Trends in epidemiology: the role of denominator fluctuation in population based estimates. AIMS Public Health. 2021;8(3):500-6. 10.3934/publichealth.2021040 - DOI - PMC - PubMed
    1. Valenciano M, Pinto A, Coulombier D, Hashorva E, Murthi M. Surveillance of communicable diseases among the Kosovar refugees in Albania, April-June 1999. Euro Surveill. 1999;4(9):92-5. 10.2807/esm.04.09.00079-en - DOI - PubMed
    1. Brown V, Jacquier G, Coulombier D, Balandine S, Belanger F, Legros D. Rapid assessment of population size by area sampling in disaster situations. Disasters. 2001;25(2):164-71. 10.1111/1467-7717.00168 - DOI - PubMed

LinkOut - more resources