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ContentslistsavailableatScienceDirect
Health
Policy
j o u r n al ho me p ag e :w w w . e l s e v i e r . c o m / l o c a t e / h e a l t h p o l
Population
density
index
and
its
use
for
distribution
of
Covid-19:
A
case
study
using
Turkish
data
Onur
Baser
a,b,c,∗aDepartmentofEconomics,MEFUniversity,AyazagaCad.No:4Maslak,34396,Sariyer,Istanbul,Turkey
bMedicalSchool,UniversityofMichigan,DepartmentofInternalMedicine,1500EastMedicalCenterDrive,AnnArbor,MI,48109,UnitedStates cJohn.D.DingellVAMedicalCenter,4646JohnRStreet,Detroit,MI,48201,UnitedStates
a
r
t
i
c
l
e
i
n
f
o
Articlehistory: Received27April2020 Receivedinrevisedform 20September2020 Accepted4October2020 Keywords: Covid-19 Populationdensity Diseasespread Flatteningthecurve Healthcare
a
b
s
t
r
a
c
t
SinceMarch2020,manycountriesaroundtheworldhavebeenexperiencingalargeoutbreakofanovel coronavirus(2019-nCoV).Becausethereisahigherrateofcontactbetweenhumansincitieswithhigher populationweighteddensities,Covid-19spreadsfasterintheseareas.Inthisstudy,weexaminedthe relationshipbetweenpopulationweighteddensityandthespreadofCovid-19.UsingdatafromTurkey, wecalculatedtheelasticityofCovid-19spreadwithrespecttopopulationweighteddensitytobe0.67 aftercontrollingforotherfactors.Inadditiontothedensity,theproportionofpeopleover65,theper capitaGDP,andthenumberoftotalhealthcareworkersineachcitypositivelycontributedtothecase numbers,whileeducationlevelandtemperaturehadanegativeeffect.Wesuggestedapolicymeasure onhowtotransferhealthcareworkersfromdifferentareastotheareaswithapossibilityofwidespread. ©2020PublishedbyElsevierB.V.
1. Introduction
Anongoingoutbreakofanovelcoronavirus(2019-nCov)was identified only a fewdays aftertheWorld Health Organization (WHO)wasalertedaboutaclusterofpneumoniaofunknown aeti-ologyinthecityofWuhan,Chinaon31December2019[1].The outbreak appears tohave started froma single zoonotic trans-missioneventormultiplezoonotictransmissioneventsatawet marketinWuhanwheregameanimalsandmeatweresold[2]and isquicklyapproaching25millionconfirmedcasesworldwide[3].
Thestartdatefortheepidemic,totalcases,andfatalitieswere differentforeachcountry.Thecountrywiththehighestnumber of cases asof August28, 2020is theUnited States,with more than6millionconfirmedcases,followedbyBrazilandIndia.There weremorethan3.5millionconfirmedcasesinEurope.Inallof theseregions,crowdedcitiesaretheepicentersforthedisease[4]. Whatsetsthesecitiesapartfromruralareasaretheirhigh popu-lationdensities.Populationweighteddensitycanbedescribedasa weightedaverageofdensityacrossthetracts,wheretractsarenot weightedbylandareabutbypopulation[5].
∗ Correspondingauthor.Permanentaddress:145HudsonStreet,Suite205,New York,NY,10013,UnitedStates.
E-mailaddress:onur@umich.edu
Densityis oneofthemostfundamentalcharacteristicsofan urbanarea[6].However,rawpopulationdensity,simply popula-tiondividedbycount,isnotagoodmeasureofthedensityatwhich thepopulationlives[5].LosAngelesisactuallydenserthanNew York,butitishemmedinbymountains,limitinghowfarthe com-mutingzonecanreach.However,accordingtopopulationweighted density,anaverageNewYorkerlivesinacensustractwithmore than12,400peoplewithinakilometersquare.Thatisthreetimes morethanthedensityofLosAngelesCounty[7].Thepopulation weighteddensityofseveralofEuropeancities,suchasBarcelona (24,600),Madrid(18,600),Valencia(17,300)andParis(13,300)are muchhigherthanNewYorkCity.Thepopulationweighteddensity ofRome(8,900),Berlin(8,200)andLondon(8,000)isalsorelatively high[8].
Especiallyinpandemiessuchascoronavirus,wherehuman con-tactisthemainreasonforspread,population-weighteddensities arebettermeasurethanconventionaldensities,becausethe varia-tionindensityacrossthesubareasmattersmorethanthedensity intotalarea.BeforeNewYorkCityplacedrestrictionsonits res-identsinordertocombatdiseasespread,thenumberofcasesin NewYorkCitywascloseto20timesthenumberofcasesinLos AngelesCounty[4].
Theaimforthispaperwasfirsttoderivepopulationweighted densityforthecitiesinTurkeyandthedistrictsforitsmajorthree citiesin2020.ThenusingthedatapointsinApril2020,weanalyzed therelationshipwiththedensityandthespreadofcoronavirusin
https://doi.org/10.1016/j.healthpol.2020.10.003
0168-8510/©2020PublishedbyElsevierB.V.
Pleasecitethisarticleas:BaserO,PopulationdensityindexanditsusefordistributionofCovid-19:AcasestudyusingTurkishdata, HealthPolicy,https://doi.org/10.1016/j.healthpol.2020.10.003
O.Baser HealthPolicyxxx(xxxx)xxx–xxx
Fig.1. PopulationWeightedDensityMapforTurkey.
those citiescontrollingforcities’educationlevel,wealth,health care force,temperature, anddemographics.We suggestthat, in conjunctionwithinformationaboutacities’numberofhealthcare workersandfatalitystatisticsinAugust2020,populationweighted densitycanalsoinformusonhowtomobilizeeachregionhealth careforcefromlowspreadriskareastohighspreadriskareas.
2. PopulationweighteddensityinTurkey
LetDbethedensityoftheurbanarea,whichisthetotal popu-lation,PdividedbythetotalareaA:
D= PA
Letpiisthepopulationandaiistheareaofsubareas,by
defini-tionP=
piandA=ai.Thereforethedensityforeachareasis
di= paii.Population-weighteddensityDpisthemeanofthesubareas
densitiesweightedbythepopulationofthesubareas:
Dp= 1
P
pidi.
Ottensmann [9] showed that the difference between population-weighted density and conventional density is a simple function of the variance in density across the census subareasandconventionaldensity.Craig[5]suggestedtheamount ofdifferenceswilldependonthevariationindensityacrossthe subareas.Wewouldexpectsimilarresultsfortheareasthathave been definedin sucha ways that theydo not include sparsely settled territory.IntheUSA,this measure hasbeen partofthe national statistics since 2010, but it has not been used yet in Turkey.
ByusingpopulationvaluesfromtheTurkishStatistical Institu-tionandareavaluesfromseveralwebsitesthatuseGoogleEarth, wecalculatedpopulationweighteddensityforeachcityinTurkey [10].
Istanbul,withapopulationofmorethan15million,wasranked asthefirstcityaccordingtopopulationweighteddensity.On aver-age,residentsinIstanbullivewith16,757peoplearoundtheir1 km2.IstanbulpopulationweighteddensityislowerthanBarcelona,
MadridandValencia.However,itishigherthanParispopulation densityandalmostdoublethatofLondon.Fig.1showsamapof Turkeywithrespecttothepopulationweighteddensityofeachof itsregions.
IzmirwastheseconddensepopulationinTurkeyaccordingto populationweightedindex,althoughitisinthirdplacewhenit comestopopulationandrawdensity.Ankarawasthethirddense population, although accordingtoraw density itwas aseighth
(TableA1).For thethreemajor cities,wealsocalculated popu-lationdensityoftheeachdistrict(TablesA2–A4)aswellastheir correspondingpopulationweighteddensitymaps.Forour knowl-edge,thiswasthefirsttimethepopulationweighteddensitiesare calculatedforTurkeyandthesethreecities(Fig.A1).
3. Method
Turkey’sHealthMinistryhasreleasedonlylimiteddataonthe spreadofthevirusandannouncedthenumberofCovid-19cases inindividualcitiesontwooccasions,onApril1standApril4th [11].AsofAugust28,2020,thereweremorethan265,000casesin TurkeyandIstanbulaccountedforalmost60percentofconfirmed casesofCovid-19.IzmirandAnkarahavebeendeclaredgrowing hotspots,aswaspredictedbypopulationweighteddensity.
Foreachcity,wecalculatedthedifferenceinthecasenumbers toproxyfor thespread ofthediseaseineachcity.Therewasa strongpositiverelationshipbetweenpopulationweighteddensity andandthespreadofthedisease(Fig.2).Correlationcoefficient wascalculatedas0.97withp−value<0.0001.
Riskfactorsincludingeducationandwealthofeachcity, num-berofhealthcareworkers,proportionofmalepopulationtofemale population,andproportionofpeopleover65yearsoldwere avail-able from the Turkish Statistical Institution. For each city we calculatedtheaveragetemperatureinCelciussince1941anduse itasanadditionalregressortocontrolfortheeffectoftemperature onspreadofthedisease[12].
Todeterminetherelationshipbetweenthesevariablesandour outcomevariable,coronaspread,weconsiderthefollowingmodel:
yj=ˇo+ˇ1x1j...+ˇkxkj+uj,
wherejindexesmcities.Allofourvariablesareatthecitylevel. Thespread,ouroutcomesvariable,definedaslogofdifferencesin casenumbersinagivencitymeasuredtwodifferenttimeperiod. However,notethatestimatingthemodelonindividualsand clus-teringstandarderrorsbycitywouldyieldthesamecoefficientsand standarderrorsasestimatingcitymeansusinganalyticweightsand standarderrorsrobusttoheteroskedasticity.
Thecoefficient[(k+1)×1]matrixˇcanbeobtained ˆ
ˇ=(X∼ ∼X)−1 ∼X∼y,
whereX and∼ ∼y obtainedbymultiplyingeachrowof[n×(k+1)] matrixXandrowof[n×1]matrixyby
wj,wjbeingthenumberFig.2.RelationshipbetweenPopulationWeightedDensityandtheDiseaseSpread.
ofindividualscontributingtotheaverage.Forstandarderrors,the variance-covariancematrixcanbecalculatedas
= 1
(m− (k+1))˜ˆu˜ˆu( ˜X ˜X)
−1
where ∼ˆu isequaltorowof[n×1]matrix ˆu multipliedby
wj[13].Thevariablessuchaspopulationweighteddensity,totalhealth careworkers,andcity’spercapitaGDPinlogarithmicformallowed ustomeasureelasticity.Theotherexplanatoryvariableswereused aslevelforms,thusprovidingsemi-elasticitymeasures.
4. Results
Onaverage,apersoninTurkeyliveswith3,868peoplewithin 1km2.Theaverageeducationlevelisaround7.5yearsand9.12%
ofthepopulationis65yearsoldandover.Thereisaslightlyhigher malepopulationthanfemalepopulationandthepercapitaincome is$9,745.Thereareabout1.9doctors,2.37nursesand2.22other healthcareworkersper1000peopleinTurkey(Table1).
Pandemics spread through the movement of and interac-tionbetweeninfectedpeople,andtheseinteractionsoccurmore frequently in places with high population weighted densities. Therefore, it has beenassumed that during pandemics suchas Covid-19,densityisassociatedwithhigherratesoftransmission, infection, and mortality[14,15]. Aftercontrolling for other fac-tors, weightedregression yield thattheelasticity ofpopulation weighteddensitywithrespecttothegrowthofcoronaspreadis calculatedas0.67(Table2).1%increasein population-weighted-densityincreasedthegrowthofthediseasespreadby.67%.
ForeachdistrictinIstanbul,wemeasuredpercentagechangesin expectedcasesrelativetothedistrictwiththeaveragepopulation density.WechooseBesiktasdistrictasareferencesince popula-tion weighteddensityfordistrictis approximatelyequaltothe densityofIstanbulasawhole.Forexample,Avcilardistrict’s
pop-ulationweighteddensityisaround10%higherthanKadikoy,so thegrowthofCovid-19casesforAvcilarwillbe6.7%higherthan Kadikoy(Fig.3).
As expected, there were significant associations between socioeconomicfactorsandthegrowthofthespread.Asis consis-tentwiththeliterature,citieswithhigher-than-averageeducation levelshadsignificantlylowerCovid-19infectionrates.Thistrend canbeexplainedbythefactsthatpeoplewithhighereducation levelshaveabetterunderstandingofthevirusandtake shelter-in-placerestrictionsmoreseriously.Theyarealsomorelikelytobe abletoworkfromhome[16].
Theproportionofthepopulationaged65yearsandolderwas alsopositivelyassociatedwiththegrowthrateincases.Each per-centagepointincreasedthegrowthrateby11%.Thismaybedueto thefactthatpeopleaged65yearsandolderhaveweakerimmune systemsthantherestofthepopulation[17].
Sincethehigherhealthcareworkersinthecityisrelatedwith thehighernumberoftesting,wefoundstrongpositivecorrelation betweentotalnumberofhealthcareworkersandthespreadofthe disease.Citieswith1%higherhealthcareworkerswereassociated with.84%higherdiseasespread.Thesefindingsareconsistentwith previousstudiesintheUSthatfoundstatewidetestingisthemost significantpredictorofthecountyinfectionrate[18].
Wangetal.previouslydemonstratedthatanincreasein temper-aturereducesthetransmissionofCovid-19[19].Wefoundsimilar resultsinTurkey.Thecitieswithhighertemperaturehadlower spreadrate.Anadditional1◦C decreasedthespreadrateby16 %.
SinceTurkeydidnotrestricttheworkingpopulationtoleave theirhouses,citieswithhigherpercapitaGDPwereassociatedwith highernumberofcases.A1%pointincreaseinGDPinthecities wasassociatedwitha1.12%increaseinthegrowthrateofthe cases.Gangemietal.alsofoundastrongsignificantrelationship betweenGDPandCovid-19casenumbersintheiranalysisusing theindicatorsfromtheWorldBank[20].
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Table1
CityCharacteristics.
Demographics N Mean STD WeightedMean WeightedSTD
NumberofCities 81
Population-Weighted-Density 543 1918 3868 6327
EducationLevel(years) 6.96 .71 7.42 0.96
Temperature(Celcius) 6.70 3.53 7.82 3.02
Doctors 1877 4200 9347 12252
Nurses 2340 4269 9994 12477
OtherHealthCareWorkers 2197 3506 8415 9840
65andoverage %10.53 3.58 9.12 3.02
PercapitaIncome $7,249 $2,570 $9,745 $4,210
ProportionofMaletoFemale 1.02 .037 1.01 .02
Fig.3. TheExpectedPercentageincreaseindistrictcasesinIstanbulrelativetoIstanbulaverage.
Table2
WeightedRegressiontoExplainLogofDifferencesinCases.
Variables Coefficient Std.Err. P>|t|
Log(Population-Weighted-Density) 0.67 0.15 0.001
Education −0.45 0.16 0.007
Log(TotalHealthCareWorkers) 0.85 0.18 0.001
Temperature −0.16 0.03 0.001
65andoverage .11 .04 0.005
Log(percapitaGDP) 1.12 0.45 0.02
ProportionofMaletoFemale 4.86 4.08 0.238
Theproportionofmalepopulationtofemalepopulationwasnot
associatedwithgrowthrateofthecases.Althoughthecoefficient
was positive,i.e. thecitieswithhigher male tofemale
popula-tionhadhighercases,thevariablewasnotsignificant.(p=0.238)
(Table2).Arecentstudyhasshownthatmenandwomenhavethe sameprevalenceforCovid-19,althoughmenwhohavetested pos-itiveforCovid-19aremoreatriskforworseoutcomesanddeath, independentofage[21].
NewlypublishedresearchontherateofCovid-19spreadinthe UShasalsoprovidedinsightonwhichfactorsaffectdiseasespread. TheresearchersexamineddatafromJanuary20,2020throughMay 25,2020from913differentmetropolitanUScounties.Theyused a regressionmodelandtookintoaccountfactorssuchas
popu-lationsize,educationlevel,anddemographicvariablesincluding age,race,andhealthcareinfrastructure(e.g.ICUbedcapacity).Inso doing,theauthorsofthestudyconcludedthatahighercounty pop-ulation,ahigherproportionofpeopleaged60andabove,alower proportionofcollegeeducatedindividuals,andahigherproportion ofAfricanAmericanswereallassociatedwithagreaterinfection rateofCovid-19[18].
5. Discussion
In epidemiological terms, ¨flattening the curve¨refers to the implementationofmeasuresthatslowtherateatwhichpeopleare infectedbythevirus,thuslesseningtheburdenonmedical profes-sionalsandthehealthcaresystem.The ¨curve¨referstotheprojected numberofpeoplewhowillcomeintocontactwithCOVID-19over aperiodoftime.Asmorepeoplecontractthevirus,theinfection curverises.Ifitrisestooquickly,thenthehealthcaresystemrisks becomingoverloaded,whichcanleadtohospitalsrunningoutof thesuppliestheyneedtohelpinfectedpeoplerecover.
Howmanypeopleagivenpatientislikelytoinfectisdefined bythereproductivenumber.Decreasingthisnumberisthe ulti-mategoalinfightingthepandemic.Ifitislessthanone,thengroup ofinfectedpeoplewouldbegeneratinglessinfection,thecurve
Fig.4.PossibleHealthCareWorkersTransferAmongtheCitiesduringtheoutbreak.Sizeofeachbubbleisproportionaltotheratioofhealthcareworkersdividedby populationweighteddensity.
wouldflatten,andeventuallydiedown.Thereproductivenumber hasfourcomponents:duration,opportunity,transmission probabil-ity andsusceptibility[22].Themultiplicationofeachcomponent givesthereproductivenumber.Durationherereferstothe dura-tionofinfectivity,notdurationofsymptoms,assomepatientsmay remainsymptomaticevenafterviralrecovery[23].Opportunityisa measureofhowmanypeopleyoucomeintocontactwithforevery dayyou’reinfections.Transmissionprobabilityisameasureofthe chancetheinfectionwillgetacrossduringaninteractionand sus-ceptibilityisameasureofthechancethepersonattheotherend oftheinteractionwillpickuptheinfectionandbecameinfectious themself.
Population WeightedDensityincreasestheopportunity com-ponentofreproductivenumberandincreasestheprobabilityof speeding up thecurve.The fasterthe infectioncurverises, the quickerthelocalhealthcaresystemgets overloadedbeyondits capacitytotreatpeople.Moreandmorenewpatientsmaybeforced togowithoutICUbeds,andmoreandmorehospitalsmayrunout ofthebasicsuppliestheyneedtorespondtotheoutbreak.
Fromapolicy-planningperspective,populationweighted den-sitycangiveaveryclearobjective:payingattentiontotheareas withhighestpopulationweighteddensity.In2009,theH1N1 pan-demic persistedforrelativelylongerperiodsoftimein areasof Taiwanthathadhigherpopulationdensities[24].Therewasa pos-itiveandsignificantrelationshipbetweenthedeathratefromthe 1918influenzapandemicandthestate-levelpopulationdensityin theUnitedStates[25].
Many countrieshave initially implemented measuresin the hopeofslowingtheCovid-19spread.Thesemeasuresincludesocial distancing,placingrestrictionsondomestictravel,and implement-ingacurfew.Althoughthesemeasureswereinitiallysuccessful, Junesawthebeginningofquarantinefatiguecausedbythe pro-foundburdenofextremesocialdistancingandeconomichardship as well as forced reopening of shuttered business, resultingin anincreasespread.Governmentsaroundtheworldfearthatthe combination ofthe cominginfluenza seasonand Covid-19 will flood hospitalswithpatients.Many countriesarerespondingto this imminentissueby augmentinghospitalcapacity, including
constructingtemporaryhospitalswithinlargespacessuchas con-ventioncenters.Themosteffectiveofthesetemporarymeasures would be constructed near the areas with highest population weighteddensities.
Foranyhealthcaresystemtoperformwellitdependsonthe availabilityofasufficientnumberofskilledhealthcareworkers. Furthermore,itiscrucialthatthesehealthworkersbemobile,since urbanareasarefirsttoexperiencespikesinCovid-19cases.For example,inthefirstmonthsoftheCovid-19epidemic,healthcare workersflewfromSanFranciscotoNewYorkCity,wheretherewas ahigherneedforservices[26].Ifsuchmobilityisavailable,we sug-gestthatattentiontopopulationweighteddensitycandirecthow thistransfermightbedone.WegraphedthecitiesinTurkeywith lowriskspread(proxiedbylowpopulationdensity)withahigh numberofhealthcareworkers(Fig.4).Thebiggreencitieslike Yozgat,Sivas,Tokatarethecitieswithlowpopulationweighted densitywithrelativelyhighnumberofhealthcareworkers,and thebrownsmallcitieslikeIstanbul,Batman,KocaeliandYalova aretheoneswithhighpopulationweighteddensitywithrelatively lownumberhealthcareworkers.Possibletransferofhealthcare workerscanbedonefromcitiesmarkedbybiggreenbubblesto citiesmarkedbysmallbrownbubbles.Notethathealthcare work-ersareonemajorresourceinthehealthsystems,butfortreating patientswithCoviditwouldnotbeenoughtoshiftworkerswithout providing/shiftingothercareresourcessuchasbeds,reanimation equipment.
Populationweighteddensitycanalsobeusedasatoolto evalu-atethesuccessoffightingwithpandemic.Wecompiledthedeath datafrom8differentcitiesinTurkey.Theseweretheonly8cities thatmakethedeathdataavailableona dailybasis online[27]. WegraphedtheseriesofdailydeathsinceMarch25,2020(two weeksafterthefirstcoronaviruscase)untilAugust30,2020for lastthreeyears(Fig.A2).Thetotaldeathsaredirectlylinkedwith thecoronavirusaswellasthosefromothercausessuchasstroke, heartdisease,andcancer.Turkey’stotalcountofcoronaviruscases onlyincludescasesthathavebeenconfirmedwithapositivetest resultanddoesnotincludecasesthathavebeenclinically diag-nosedwithnotest.Thetotalnumberofdeathsindicatefatalities
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Table3
AscendingRankingofIncreaseinDeathbetweenMarch15toAugust30,2020relativetoaverageoflastthreeyears,controllingforpopulationweighteddensity.
Cities PopulationWeighted
Density(Ranking)(A)
Excess Death(B) B/A Population Density(C) B/C Kocaeli 1916(4) 237 0.12 541 0.44 Istanbul 16757(1) 4771 0.28 2987 1.60 Bursa 1903(5) 757 0.40 293 2.58 Denizli 433(19) 213 0.49 89 2.39 Malatya 260(26) 221 0.85 68 3.25 Sakarya 535(15) 1116 2.08 213 5.24 Kahramanmaras 129(42) 363 2.81 80 4.54 Konya 165(33) 795 4.81 57 13.95
thathavecoincidedwiththeonsetoftheoutbreak,thoughtheyare
notnecessarilyattributedsolelytothecoronavirus.
Foreightcitiesweselected,wecalculatedtheincreaseamount
ofdeathrelativetoaverageoflastthreeyears.Wethendivided
thisnumberwithpopulationweighteddensitytodetermine,
con-trollingforthedensity,theproportiondeathperdensitymeasure
(Table 3).Consistent withpreviousresearch, citieswith higher populationdensitiestendtohavelowerdeathrates,possiblythey enjoyedahigherlevelofdevelopmentincludingbetterhealthcare systems.Therecentanalysisfoundthataftercontrollingforfactors suchasmetropolitansize,education,raceandage,doublingthe activitydensitywasassociatedwithan11.3percentlowerdeath rate[18].
6. Conclusions
Theimpactofpopulationdensityontherateofspreadof emerg-inghighlycontagiousinfectiousdiseaseshasrarelybeenstudied. ThecurrentCovid-19pandemicallowsustoinvestigatethese rela-tionships.Ourstudyusesaregressionmodeltostudytheimpact of population weighted density on Covid-19 spread in Turkey while controllingfor keycompounding. We foundthat popula-tion weighted densityis one of the mostsignificantpredictors ofinfectionrates.However,countieswithhigherdensities have significantly lowervirus-relatedmortalityrates, possiblydueto superiorhealthcaresystems.
Mostofthedataispreliminaryduringtheoutbreakandthedata thatwecanuseinTurkeyislimited.Wewereabletoupdateour analysisforthedeathstatisticsbyAugust30th.However,the Turk-ishministryofhealthhasnotpublishedcasenumbersbycitiesafter April2,2020.Becauseofthis,theresultsinTable2havenotbeen updatedbeyondApril2,2020.However,ourresultswereconsistent withthepreviousresearch[14,16–21].Additionally,weareunable tomeasurethenumberofpatientswithunderlyingconditionsin eachcity,whichwoulddecreasethesurvivalrateofeachofthese regions.WehaveseendeathtollraiseinacitieslikeZonguldak wheremostofthepopulationsuffersfromchroniclungdiseases duetoworkconditionsintheminingslocatedinthecity.Wehave usedthedeathstatisticstomeasurethesuccessofdealingwith theoutbreak, butanydeathstatistics inthemidstofpandemic aretrickytopindownandmustbeconsideredpreliminary.We haveseenmostofthecountriesareimprovingtheirdeathstatistics, whichtheynowacknowledgeincomplete.
In order to control and manage the outbreak, our analysis suggeststhat populationweighteddensity canbeausefultool. According to previous research, there are many advantages of compact development. It is associated with with open space preservation,higherinnovationandoveralleconomicproductivity, greatersocialcapital,lesslikelihoodofobesityandrelatedchronic diseasesandincreasedoveralllifeexpectancy[28–32].However, compactdevelopmentcanbebig ¨enemy¨inthecoronavirusfight [15].Highdensitymeansthatpeopleinthoseareaslivevery differ-entlyfromotherpeople.Thosewholiveorworkinornearthecity
shopandcommutedifferently:theyarefarmorelikelytowalkor takepublictransitthantherestofthepeople.Thediseasespreads fasterintheareaswithhighpopulationweightedareasthen else-wheresimplybecausethereissomuchhumancontact.
Atthisstage,particularattentionshouldbegiventothe preven-tionofspreadinginthehighestdenseareasdirectedbypopulation weighteddensity.Theconceptof ¨flatteningthecurve ¨ultimately assumesthatthesamenumberofpeoplewillcontractthe coro-naviruswhetherornotthecurveissteeporflattened.Ifthecurve isflattened,however,thereislessstressplaceduponthehealth caresystem,whichresultsinbetterhealthcareaccessforthose whoaresick.
DeclarationofCompetingInterest
Theauthorsreportnodeclarationsofinterest.
Acknowledgments
None.
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