A dataset to assess mobility changes in Chile following local quarantines | Scientific Data - Nature.com

As of September 2022, the COVID-19 pandemic is simply a planetary menace that resulted successful astir 600 cardinal infected radical and much than six cardinal deaths globally¹. In South America, Chile is among the astir severely affected countries, with much than 4.6 cardinal infected radical and a decease toll that surpassed the 60,000 people arsenic of September 2022. Similarly to different severely affected countries^{2,3,4,5,6,7,8,9}, Chile implemented Non-Pharmaceutical Interventions (NPIs) specified arsenic determination lockdown, stay-at-home orders, and question restrictions, successful an effort to mitigate the COVID-19 epidemics done reducing idiosyncratic mobility and promoting societal distancing. In opposition with countries specified arsenic China, Italy, and the USA, which implemented NPIs astatine the nationalist oregon determination level^2,6,8,9, Chile’s implemented NPIs astatine the comuna level. Comunas, besides known arsenic municipalities oregon communes successful different countries, are the smallest administrative (political) subdivision successful Chile^10,11. There are 346 comunas successful Chile. Without counting Antártica, the largest comuna with an country of 1.25 cardinal quadrate kilometres, the remaining 345 comunas person a mean country of 2,199 km² (stdev. 4,824 km²), with the smallest being San Ramón, Lo Prado, Lo Espejo, and Independencia, with 7 km² each, and the largest is Natales successful the Magallanes region, with an country of 4,8974 km². Two comunas successful the aforesaid portion whitethorn beryllium regulated by antithetic NPIs: whereas 1 is successful lockdown, adjacent ones mightiness person nary question restrictions. Only 1 comuna, Santiago, was divided successful fractional successful presumption of NPIs, with 1 fractional nether quarantine portion the different not. Given the peculiarity of NPIs’ spatial standard successful Chile, tracking mobility changes astatine the comuna level is important to measure section quarantines’ efficacy and measurement the effect of mobility reductions connected predicting the microorganism spread¹². While indices of changes successful quality mobility bash beryllium astatine the determination level successful Chile (e.g., the Google Mobility Reports¹³), determination are nary authoritative indices astatine the comuna level.

Mobile telephone records supply an unprecedented accidental successful tracking quality movements^{14,15,16,17,18}, allowing for estimating presences and colonisation density^19,20,21, mobility patterns^{16,22,23,24,25,26}, flows^27,28,29,30, and socio-economic status^{31,32,33,34,35,36}. When utilized correctly and adequately aggregated to sphere privacy^37,38,39,40, mobile telephone information correspond a important instrumentality for supporting nationalist wellness actions crossed the phases of the COVID-19 pandemic^12,41. Motivated by the imaginable of mobile telephone information successful capturing the geographical dispersed of epidemics^42,43,44,45, researchers and governments person started to collaborate with mobile web operators to estimation the effectiveness of power measures successful respective countries^{2,10,46,47,48,49,50}.

To measure the interaction of the NPIs imposed by Chilean authorities successful effect to the epidemics, we analyse a mobile telephone dataset provided by Telefónica Chile, which comprises 31 cardinal eXtended Detail Records (XDRs) and 5.4 cardinal users distributed each implicit the state covering the play February 26th, 2020 to September 20th, 2020. An XDR is created each 15 minutes if a definite threshold of postulation has been reached, frankincense describing idiosyncratic movements successful large detail²¹. From the XDRs, we deduce 3 epidemiologically applicable metrics: the Index of Internal Mobility (IM_int), which quantifies the magnitude of mobility wrong each comuna of the country; the Index of External Mobility (IM_ext), quantifying the mobility betwixt comunas; and the Index of Mobility (IM), which considers immoderate movement, some wrong and betwixt comunas. We analyse however these metrics alteration arsenic the COVID-19 epidemics dispersed retired successful Chile, highlighting a sizeable heterogeneity of effect to section quarantines crossed the country.

The datasets we marque disposable volition turn arsenic clip goes by and, to the champion of our knowledge, are the lone ones describing mobility changes and dates of section quarantines successful Chile astatine the comuna level. They tin beryllium utilized not lone for warring against the COVID-19 epidemics but volition besides payment different probe and applications specified arsenic exigency response^51,52 and assemblage travel prediction^14,53,54,55. The datasets described are presently utilized astatine each levels of the Chilean government.

Mobile telephone operators cod respective antithetic streams of mobile phones enactment with the cellular web for billing and operational purposes. Among them are the eXtended Detail Records (XDRs), a substance of human- and device-driven event, triggered either by explicitly requesting an HTTP code oregon automatically downloading contented from the Internet (e.g., emails) each 15 minutes and astatine definite postulation thresholds. Formally, an XDR is simply a tuple (u, t, A, k), successful which determination is lone 1 operation A involved, u is the caller’s identifier, t is simply a timestamp of erstwhile the grounds is created, and k is the magnitude of downloaded accusation (Fig. 1a). Rather than capturing trips, we are funny successful detecting immoderate “movement”, i.e., immoderate modulation betwixt 2 antennas. From an epidemiological constituent of view, transitions supply a utile denotation of people’s displacements and hence utile accusation astir the movements of the microorganism betwixt areas wrong the aforesaid comuna oregon betwixt 2 comunas. Even if an individual’s question betwixt 2 antennas whitethorn not beryllium a travel from a semantic constituent of view, it denotes the question of the microorganism betwixt those 2 antennas anyway. To this purpose, from the XDRs of the individuals, we specify 2 types of movement. Every clip a idiosyncratic moves from 1 operation to different wrong the aforesaid comuna, they make an intra-comuna movement. Every clip the idiosyncratic moves from an operation to different successful a antithetic comuna, they make an inter-comuna question (Fig. 1b). For each time and comuna, we conception 3 indicators of mobility based connected the intra- and inter-comuna movements:

1. 1.

   IM_int (Index of Internal Mobility), the fig of intra-comuna movements for that day;

2. 2.

   IM_ext (Index of External Mobility), the fig of inter-comuna movements for that day;

3. 3.

   IM = IM_int + IM_ext (Index of Mobility).

Fig. 1

(a) Illustrative illustration of eXtended Detail Records (XDRs) of a mobile telephone user. The hexagons correspond mobile telephone towers and greenish dots the positions wherever the idiosyncratic starts a download/upload operation. The dotted enactment indicates the existent question of the user, from the near to the right. (b) Intra-comuna movements (black arrows) and inter-comuna movements (orange arrows). Hexagons of the aforesaid colour bespeak towers that autumn successful the aforesaid comuna.

All the 3 indices ranges successful [0, ∞), wherever a worth of 0 indicates nary mobility astatine all. We normalize the 3 indices with respect to the fig of users that reside successful the comuna, estimated arsenic the full fig of unsocial mobile devices whose location operation falls successful that comuna. Each device’s location operation is computed arsenic the operation successful which it has the highest fig of XDRs during nighttime (between 7 pm and 7am, inclusive)0^21,56. The fig of estimated nonmigratory users successful the comunas is powerfully correlated (R² = 0.96, slope = 4.37, intercept = 298.30) with the authoritative colonisation of the comunas arsenic per the authoritative 2017 Chilean Census.

The earthy datasets were provided by Telefónica/Movistar Chile, a mobile telephone institution which possesses betwixt 29–32% of the Chilean mobile telephone market. Telefónica gathers information for billing purposes and for web attraction purposes by persisting web events. Users are not allowed to “opt-out” of billing information, arsenic stated successful the presumption and conditions below. They are, however, capable to opt retired of the usage of idiosyncratic information by calling a fig oregon visiting the Telefónica website (see leafage 3, conception 6) of Telefónica’s Terms and Conditions (see⁵⁷ successful Spanish). In this study, nary idiosyncratic information oregon accusation whatsoever is utilized successful the instauration of the dataset projected present (in fact, it’s lone the aggregated fig of transitions betwixt rtowe)s, without immoderate idiosyncratic information.

From the earthy datasets we conception the 3 mobility indices described above. The datasets are released nether the CC BY 4.0 License and are publically disposable at⁵⁸. Table 1 shows the operation of the dataset describing the mobility indices. Each grounds refers to a comuna successful Chile and describes:

• the authoritative sanction of the portion (region, type:string);

• the identifier of the portion arsenic per the authoritative 2017 Chilean Census (rid, type:string);

• the authoritative sanction of the comuna (comuna, type:string);

• the identifier of the comuna arsenic per the authoritative 2017 Chilean Census (cid, type:string). All maps and their authoritative identifiers tin beryllium downloaded from the National Statistics Office of Chile⁵⁹;

• the country of the comuna successful km² (area, type:float);

• the values of IM, IM_int and IM_ext for that time (type:float);

• the time the IM, IM_int and IM_ext values notation to (date, type:date).

Table 2 shows the operation of the quarantines dataset. Each grounds refers to a quarantine regularisation and describes:

• the identifier of the quarantine regularisation (qid, type:integer);

• the authoritative sanction of the comuna (comuna, type:string);

• the presumption of the quarantine, that tin beryllium either progressive oregon not progressive (status, type:string);

• the sum of the quarantine, that tin beryllium either partial, rural, oregon implicit (coverage, type:string);

• the day the quarantine started (start, type:date);

• the day the quarantine ended, which is “ - ” if it is inactive progressive (end, type:date);

• the identifier of the comuna arsenic per the authoritative 2017 Chilean Census (cid, type:string);

• the country of the quarantine successful m² (area, type:float);

• the perimeter of the quarantine (perimeter, type:float).

A regulation of each phone-records studies concerns the presumption of towers and the geographical country they “illuminate” oregon service fixed their method specifications. There whitethorn beryllium towers that service 2 neighboring comunas, for example, impacting our question counts. However, 2 phenomena mitigate this problem: (i) comunas are mostly large, and eventual borderline events are scarce fixed the 15-minute span; and (ii) telco companies bash not grounds each antenna interactions by mobile devices, due to the fact that storing each that accusation would beryllium costly. In our case, an lawsuit (a telephone grounds oregon XDR) is typically generated each y minutes and if and lone if the instrumentality has crossed a threshold of x MegaBytes (MBs) of postulation (not revealed by the institution arsenic it is an concern secret). A two-rule heuristic determines the quantities x and y. A “clock” triggers a regularisation each 15 minutes: if the idiosyncratic has reached x MBs astatine either 15, 30, oregon 45 minutes, the strategy appends a caller XDR successful the database. Some dense users volition usage up the x MBs threshold astatine 15 minutes (if they are watching movies connected the web, for instance), astir astatine 30 minutes, and a fewer airy users volition scope the threshold astatine 45 minutes. There is besides a just stock of frequence astatine different times. The 2nd regularisation states that if the power level of the mobile web notices immoderate peculiar telephone events, specified arsenic immoderate antenna handovers, turning disconnected the phone, oregon losing connection, past a grounds is created into the database astatine immoderate clip (irrespective of the megabytes used), making it imaginable to find events anyplace in-between the clock’s 15-minute triggers.

In our analysis, we see 2 periods: the pre-quarantine period, from March 9th to March 15th, 2020, and the quarantine period, from June 22nd to June 28th, 2020. Although we person 2 weeks earlier March 9th, the modulation from February to March marks the commencement of the Fall schoolhouse semester successful Chile. In 2020, March 6th was the commencement of the semester, truthful we presume that the “business arsenic usual” play would beryllium champion represented by the week of March 9th until March 15th. March 16th marked the commencement of NPIs successful Chile, with the closure of schools, universities and ample nationalist gatherings. After that, connected March 26th, determination was a partial lockdown of 7 comunas successful the Metropolitan Region. By June 22–28, much than fractional of the colonisation of the state was nether quarantine, and mobility was astatine 40% reduction.

During the pre-quarantine period, comunas with precocious mobility indices and comunas with debased mobility indices coexist. Geographically, high-mobility comunas are concentrated adjacent municipality areas specified arsenic the superior Santiago and, successful general, successful the halfway of the state (Figs. 2a, 3a, 4a, and 5a). The bluish and confederate parts of Chile person less high-mobility comunas. The comunas with the highest mobility registered during the pre-quarantine play are located successful the regions of Metropolitana de Santiago, Arica y Parinacota, Valparaíso, Ñuble, and Magallanes (Table 3).

Fig. 2

Choropleth maps of IM, IM_int and IMext for the comunas successful bluish Chile for the pre-quarantine (first row) and the quarantine (second row) periods.

Fig. 3

Choropleth maps of IM, IMint and IM_ext for the comunas successful cardinal Chile for the pre-quarantine (first row) and the quarantine (second row) periods.

Fig. 4

Choropleth maps of IM, IM_int, and IM_ext for the comunas successful confederate Chile for the pre-quarantine (first row) and the quarantine (second row) periods.

Fig. 5

Choropleth maps of IM, IM_int and IM_ext for the comunas successful the metropolitan country of Santiago de Chile for the pre-quarantine (first row) and the quarantine (second row) periods.

The top-ten comunas with the highest mobility indices alteration during the quarantine period, but for Rinconada successful the portion of Valparaíso (Table 4), mirroring the antithetic grade of simplification successful quality mobility successful the Chilean regions (Fig. 6). All regions amusement a simplification successful each 3 mobility indices during the quarantine period, albeit with antithetic intensities (Fig. 7). At the comuna level, high-mobility comunas are uncommon and clustered adjacent the ample municipality areas located successful cardinal Chile (Figs. 2–5).

Fig. 6

Values of IM, IM_int, and IM_ext of the comunas successful the apical 10 ranking computed for the pre-quarantine and quarantine period. The coupled bars correspond comunas corresponding to the aforesaid presumption successful the rank.

Fig. 7

Evolution of IM (a), IM_ext (b) and IM_int (c) from March to September 2020 for the 16 regions successful Chile. The curves are sorted successful descending bid respect to the comparative scale of mobility of the corresponding comuna. The vertical lines denote important dates regarding NPIs successful Chile; the fig successful parentheses indicates the fig of comunas taxable to that restriction.

These results are supported by the distributions of the mobility indices of the 2 periods (Fig. 8). There is simply a wide displacement towards the near of the organisation of the IM scale (Fig. 8a): (i) the mean IM during the quarantine play (5.16 ± 2.74) is 27.6% little than the mean IM during the pre-quarantine play (7.13 ± 4.15); (ii) the organisation of IM during the quarantine play is much skewed to the left, showing a alteration of the mobility successful Chile during the selected days. Regarding IM_int and IM_ext, we observe nary nett displacement of the curve, but alternatively a flattening, suggesting that intra- and inter-comuna movements decreased during the quarantine (Fig. 8b,c).

Fig. 8

Distributions of IM (a), IM_ext (b) and IM_int (c) for the pre-quarantine (blue) and quarantine (orange) periods, with the mean values of 3 comunas: Santiago, Camarones and Torres Del Paine. (d) Distribution of IM_red for each the Chileans comunas.

We further analyse the simplification of the mobility defining IM_red arsenic the comparative simplification of the IM scale successful the quarantine play with respect to the pre-quarantine period. The organisation of IM_red shows that a ample fig of comunas person a reduced mobility, pursuing Chilean authorities interventions, by an mean of 25.37% ± 43.2 (Fig. 8d). However, comunas that were not successful quarantine during the quarantine play bash not trim their mobility importantly (Fig. 9a).

Fig. 9

(a) Percentage of colonisation nether quarantine and the percent of mobility simplification IM_red from February 26th to September 20th, 2020. (b) Evolution of IM scale successful Santiago; the bluish country denotes the quarantine period. The vertical lines denote important dates regarding NPIs successful Chile; the fig successful parentheses indicates the fig of comunas taxable to that restriction.

The percent of colonisation that unrecorded successful comunas wherever the authorities applied NPIs increases with clip (Fig. 9a) reaches its highest (≈57%) successful precocious July 2020. With the summation of the fig of radical nether quarantine, IM_red initially increases, but it somewhat decreases implicit clip adjacent if some the fig of individuals and the fig of comunas nether quarantine increase. This improvement suggests that mobility restrictions are much effectual successful the short-medium word and go little effectual arsenic clip goes by, and it tin beryllium observed some astatine determination (Fig. 7) and comuna level (Fig. 9a,b).

Unfortunately, we bash not person crushed information information to comparison our information with due to the fact that determination are nary authoritative indices astatine the comuna level successful Chile. However, different mobility reports bash beryllium for the aforesaid country and play astatine the determination level (not comunas), specified arsenic Google Mobility Reports¹³. By aggregating our information astatine the determination level and comparing them with Google’s data, we find a beardown Pearson correlation (r = 0.7), suggesting that our mobility scale is reflecting mobility trends captured by different reliable information sources.

Limitations of our dataset

Mobile telephone records are sparse and irregular successful time, starring to gaps betwixt the user’s existent trajectory and the trajectory that tin beryllium inferred from their integer trace¹⁵. Chen et al.⁶⁰ suggest an algorithm to reconstruct idiosyncratic trajectories from CDRs by recovering the unspecified positions of each user. They revisit the seminal enactment of Gonzalez et al.²³, successful which the authors amusement that heavy-tails characterise the distributions of (charateristic) distances traveled by individuals, showing that CDRs sphere the mobility patterns observed successful the reconstructed (denser) trajectories, though somewhat underestimating agelong trips and overestimating abbreviated ones⁶⁰. Considering that successful our survey we usage XDRs, which are mode denser than CDRs, we tin presume that the mobility traces of individuals represented successful our dataset bash not disagree importantly from the existent user’s trajectory.

The up-to-date information are disposable from the wide repository of the Ministry of Science of Chile at: https://raw.githubusercontent.com/MinCiencia/Datos-COVID19/master/output/producto33/IndiceDeMovilidad.csv (IM indeces), and https://github.com/MinCiencia/Datos-COVID19/blob/master/output/producto29/Cuarentenas-Activas.csv (quarantines). The codification to download the up-to-date information automatically and to reproduce the investigation successful our insubstantial is disposable at⁵⁸.

References

Authors and Affiliations

1. ISTI-CNR, Pisa, Italy

   Luca Pappalardo & Giuliano Cornacchia

2. Department of Computer Science, University of Pisa, Pisa, Italy

   Giuliano Cornacchia

3. Faculty of Engineering, Universidad del Desarrollo, Santiago, Chile

   Victor Navarro, Loreto Bravo & Leo Ferres

4. Telefónica R&D Santiago, Providencia, Chile

   Loreto Bravo & Leo Ferres

5. ISI Foundation, Turin, Italy

   Leo Ferres

Contributions

L.F., V.N. and L.B. developed and computed the mobility indices. L.P., L.F. and G.C. analyzed the data, made the plots and wrote the paper.

Corresponding author

Correspondence to Leo Ferres.

Competing interests

The authors state nary competing interests.

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