Estimating COVID-19 cases and outbreaks on-stream through phone-calls

TL;DR

This paper introduces an algorithm that estimates COVID-19 cases in real-time using phone call data, enabling early outbreak detection before lab confirmations, thus aiding timely public health responses.

Contribution

The paper presents a novel algorithm that models phone call data to estimate COVID-19 cases and detect outbreaks in advance, with detailed uncertainty tracking and validation using real data.

Findings

High correlation (R^2 > 0.85) between calls and cases in Buenos Aires

Successful early outbreak detection in Villa Azul

Algorithm provides timely alerts before lab results

Abstract

One of the main problems in controlling COVID-19 epidemic spread is the delay in confirming cases. Having information on changes in the epidemic evolution or outbreaks rise before lab-confirmation is crucial in decision making for Public Health policies. We present an algorithm to estimate on-stream the number of COVID-19 cases using the data from telephone calls to a COVID-line. By modeling the calls as background (proportional to population) plus signal (proportional to infected), we fit the calls in Province of Buenos Aires (Argentina) with coefficient of determination $R^2 > 0.85$. This result allows us to estimate the number of cases given the number of calls from a specific district, days before the lab results are available. We validate the algorithm with real data. We show how to use the algorithm to track on-stream the epidemic, and present the Early Outbreak Alarm to detect outbreaks in advance to lab results. One key point in the developed algorithm is a detailed track of the uncertainties in the estimations, since the alarm uses the significance of the observables as a main indicator to detect an anomaly. We present the details of the explicit example in Villa Azul (Quilmes) where this tool resulted crucial to control an outbreak on time. The presented tools have been designed in urgency with the available data at the time of the development, and therefore have their limitations which we describe and discuss. We consider possible improvements on the tools, many of which are currently under development.