Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

UnderstandingVaccineEconomicswithSimulationsAuthors:DavidBishaiandSasmiraMattaLearningObjectives:• TounderstandthePhilipsoneffectorratherhowacceptabilityofavaccineis

determined• Tounderstandthedifferencebetweencostversusbenefit• Tounderstandthereisnorightanswerindetermininghowtogoaboutdecision-

making• Tousesimulationstobetterunderstandvaccineeconomics

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

UnderstandingVaccineEconomicswithSimulationsAuthors:DavidBishaiandSasmiraMattaInthisexercise,youwillbeusingfoursimulations.Onewillexaminethedynamicsinasinglecountry,andtheotherthreewillexaminethedynamicsofneighboringareas.YouwillbeusingtheForiosoftwaretoanalyzehowthepopulationofinfectedchildrenandthecoveragechangesasaresultofdifferentscenarios.SingleCountryModel:Thefollowingdiagramisacausalloopdiagram.Itrepresentsthedynamicsthatareoccurringinasingularcountry.FigureI.

Inordertounderstandthisdiagram,itisimportanttounderstandwhatisincludedinthemodel.ThisisamodifiedSIRmodel,whereSIRisanacronymforSusceptible,Infected,andRecovered.ASIRmodelisanepidemiologicalmodelthatcomputesthetheoreticalnumberofpeopleinfectedwithacontagiousillnessinaclosedpopulationoftime[1]. Thearrowsshowthedirectionofinfluenceforeachvariable.Sincewearealsomeasuringvaccinecoverage,thismodelalsotracksthenumberofchildrenwhoreceivethevaccine.Inthemodel,wehavefourboxedvariables:SusceptibleS,InfectedI,RecoveredR,andImmune.Eachofthesevariableswillcomputethenumberofchildrenwhofallintoeachcategoryateachpointintime.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

Thearrowswiththelargerheadsandrectangularbodiesaretheflowsandtheyrepresenttherates.Inthismodel,wehavefourflows:getsinfected,getsbetter,getsvaccinated,andimperfectvaccination.Eachoftheseflowsmeasurestherateatwhichachildmovesfromoneboxtoaconnectingbox.Ex.Ifwesaythattherateof“getsvaccinated”is80/1000,thismeansthatforevery1000children,80willgetvaccinatedateachtimestep.Theothervariablesthatareconnectedtothediagrambythesmallerarrowsareotherimportantfactorsthatinfluencetheboxedvariablesandtherates.Thefollowingtablesummarizesthevariablesusedintheabovediagramandtheelementstheymeasure.TableI.DiagramKeyDiagram DefinitionSusceptibleS Measuresthenumberofchildrenthat

aresusceptibletomeaslesInfectedI Measuresthenumberofchildrenthat

areinfectedwithmeaslesRecoveredR Measuresthenumberofkidswho

recoverafterhavingthemeaslesImmune Measuresthenumberofchildrenwho

receivethevaccinationGetsInfected Rateatwhichasusceptiblechildgets

sickwithmeaslesGetsBetter Rateatwhichaninfectedchildrecovers

frommeaslesGetsVaccinated Rateatwhichsusceptiblechildrenget

vaccinatedImperfectVaccination Rateatwhichvaccinationisimperfect

anddoesnotpreventdiseaseforchildInfectionProbability Likelihoodofbeinginfectedwith

measlesRecoveryTime Timeittakesforachildtorecoverfrom

measlesAcceptability Measuresthecountry’sperceptionof

vaccinesafetyandefficacyVaccineCoverage Proportionofchildrenthatare

vaccinatedProbabilityofaMishap Probabilitythatthevaccinewillnot

induceimmunityThefollowingsimulationshavebeendesignedtoreinforcedifferenttopicsinvaccineeconomics.Whenansweringquestionfocusonchangesandshift,anddonotgetstuckonwhetherornotdifferencesaresignificantunlessotherwiseasked.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

SIMULATION1:UnderstandingthePhilipsonEffectThePhilipsonEffectisatheorystatingthatasavaccinepreventablediseasedisappears,sotoodoesthedemandforvaccines.Inotherwords,asadiseasebecomeslessprevalent,parentsarelesslikelytogettheirchildrenvaccinated[2].AccordingtoGeoffardandPhilipson,thedemandforavaccineisproportionaltothebenefitofbeingvaccinated.Theypointoutthatifanindividualrealizesthatcoverageisveryhigh,arationalpersonwouldrealizethatherdimmunityisprotectingthemandthattheirpersonalbenefitfromavaccinationislow.Arationalandselfishpersonwouldbelessandlesslikelytowantavaccineastheriskofdiseasegoesdowntothepriorsuccessofthevaccineprogram.Intheseexercises,wewillconsideravaccinetobeperfectifitwilldefinitelyimmunizeachild.Therefore,everychildwhoisvaccinatedwilldefinitelybeimmunetothedisease.Ontheotherhand,animperfectvaccineisavaccineinwhichthereisachancethatachildwillnotbeimmunetoaparticulardiseaseevenifthechildreceivesthevaccine.Inthissimulation,youwillbeabletotrackthreethings—theinfectedpopulation,vaccinecoveragewiththePhilipsoneffect,andvaccinecoveragewithoutthePhilipsoneffect.Asyourunthesimulation,focusonhowthecoveragecurvesdiffer.1.Gotothewebsitehttps://forio.com/simulate/smatta1/single-country2.Youshouldseethefollowingonyourscreen

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

3.Clicktheresetbutton.Startwiththeslidertoolontheperfectvaccinesetting.

4.Clicktheadvancebuttonsixtimessothatthesimulationrunstocompletion.Thisiswhatyoushouldseeonthescreen.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

Whichvaccinecoveragecurveresemblestheinfectedpopulationcurve?Doesthismakesensetoyou?Explain.ThecoveragecurvethattakesthePhilipsonEffectintoconsiderationfollowstheinfectedpopulationcurve.ThismakessensebecauseasthePhilipsonEffectindicates,astheinfectedpopulationincreases,sodoesthecoverage.Astheinfectedpopulationdecreases,sodoesthecoveragerate.Ontheotherhand,thevaccinecoveragecurvewithoutthePhilipsoneffecthasadifferentcurvature,whichmeansthatthecoverageischangingatadifferentratefromtheinfectedpopulationcurve.ThismeansthatthecoveragewithoutthePhilipsoneffectisbeingmeasureddifferently.5.Clicktheresetbutton.Movethedecisionsliderallthewaytotherighttotheimperfectvaccinationsetting.Nowclicktheadvancebuttonuntilthesimulationfinishesrunning.Afterrunningthroughthesimulation,youshouldseethefollowingonyourscreen.

HowdoesthePEAKoftheinfectedcurvedifferwithrespecttotheprevioussimulation?Aretheremoreorlesschildrenwhoareinfected?Explain.Undertheperfectvaccinesettingwesee725childrenareinfectedwhereasintheimperfectvaccinesettingweseethat736childrenareinfected.Therearemore

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

childreninfectedwhenthevaccinedoesnotworkaswell,whichmakessensebecauseitdoesnotguaranteefullimmunity.Inthesimulation,youseethatwhenthevaccineisimperfect,about11morechildrenwillgetinfected.Ifparentsstartseeingthattheirvaccinatedchildrenareinfactgettingsick,atwhatpointdoesthisposeaproblem?Howcanyoucommunicatevaccineefficacytoparents?Participantsshouldusetheirownexperiencestoanswerthisquestion.Underwhichsettings—PhilipsonorNoPhilipsoncurvesdoweachievemorecoverage?Whycouldthisbethecase?WhenweoperatewithoutconditionsofthePhilipsoneffect,weachievemorecoverage.ThisisthecasebecausewhenweconsiderthePhilipsoneffect,parentsarechoosingwhetherornottovaccinatetheirchildrenbasedonthediseaseprevalence.WithoutthePhilipsoneffect,weassumethatthecoveragerateisindependentofdiseaseprevalence.NowthatwehaveseenthatthePhilipsoneffecthasthepotentialtodrasticallychangethecoverage,whatdoyoudo?Howdoyouworkandcommunicatewithparentsandconvincethemthattheyshouldbegettingtheirchildrenvaccinated?Howdoyoupreventthemfromworrying?Itwouldbegreattotalkaboutthisquestionasagroup.Participantsmighthaveinterestingexperiencestoshareandtalkabout.NowthatwehavewalkedthroughthePhilipsoneffectunderbothperfectandimperfectvaccineconditions,itisnowtimetomovetoatwo-countryscenario.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

TherewasabotchedmeaslescampaigninDistrictAwhere15childrenwhoreceivedthevaccinationdied.Itwasreportedthatthevaccinationswerenotstoredproperly,andthattheneedleswereusedmultipletimes.YouareinchargeoftheEPIofficeinDistrictB.DistrictAneighborsDistrictB.YouareresponsibleforimprovingmeaslescoverageinDistrictB,especiallynowthatparentsarewearyofgettingtheirchildrenvaccinatedafterhearingthenews.Thenexttwosimulationsfollowsimilardynamicsaswehavealreadyseeninthesingularcountrycausalloopdiagram.Infact,ifyoulookatthemodelbelow,thesinglecountrymodelwascopiedandpastedtwice.Ontheleft-handside,wehaveDistrictA,andontheright-handsidewehaveDistrictB.FigureII.AMoreDynamicModel(LeftSideRepresentsDistrictAandtheRightSideRepresentsDistrictB).

Therearetwomaindifferencesthatdistinguishthetwo-districtmodelfromthesinglecountrymodel.I)ThereisacommunicationvariablewhichisdenotedasCommforDistrictAandComm0forDistrictB.Thisvariablecontrolswhetherornotthecommunicationorthedisseminationofinformationsurroundingvaccinesispositiveornegative.II)ThereisanarrowgoingfromDistrictA’sAcceptabilitytoDistrictB’sAcceptabilityandviceversa.Thisdemonstratesthetransmissionofinformationbetweenthedistricts—informationtravels!Whatsocial,cultural,andmediaeventsareexamplesofnegativeinformationonvaccineacceptance?Whilestudentswillprobablyhavemanydifferentanswersforthisquestion,itisimportantthattheyunderstandthatnegativeinfluencewillleadtodecreasedacceptabilityofvaccines.Ifastudentisstuckthekeyquestiontoaskis“whatcanyouintroducethatwilldriveacceptabilitydown?”

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

Possibleanswersinclude(butarenotlimitedtothefollowing):Witchdoctorsadvocatingforchildrentonotbevaccinated,botchedmeaslescampaigninthecountry,governmentwarningagainstvaccinationofchildren,etc.Whataresocial,cultural,andmediastrategiesareexamplesofpositivecommunicationonvaccineacceptance?Similartothequestionabove,ifastudentisstuck,encouragethestudenttothinkaboutwhatwouldincreaseacceptabilityinacountry.Possibleanswersinclude(butarenotlimitedtothefollowing):Governmentadvocatesforvaccinations,publicfigures(likecelebrities)advocateforvaccinations,religiousleadersadvocateforvaccinations,etc.Nowwewillexplorethetwo-districtmodelonForiointhreescenarios,whichareoutlinedbelow.RememberthatineachofthefollowingscenariosyouareintheEPIprogramofDistrictB.SIMULATION2:DoNotCensortheMediaInthissimulation,youhavedecidedtocensorthemedia.ThismeansthatthebadnewsaboutbotchedmeaslesvaccineinDistrictAcannotreachDistrictB.Inthissimulation,youcanmanipulatethecommunicationsurroundingvaccinesinthedistricts.Themorenegativethecommunicationis,themoreyoucandecreaseacceptabilityinthecountryandviceversa.TheBotchedVaccinesinDistrictAslidercanbeadjustedtoindicatetheseverityofthebotchedcampaigninDistrictA.TheBotchedVaccineinDistrictAwillaffecttheprobabilityofavaccinemishap.Themoresevereitis,themoreimperfectthevaccineis,andthemoreproblemsitwillcause.Ifyouhoveroverthecurves,thetooltipwilltellyouthecountrythatyouarelookingatandthevalueatthemoment.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

1.Gotohttps://forio.com/simulate/smatta1/south-sudan-and-uganda-1.Thefollowingisanimageofwhatyoushouldseeonthescreen.

2.Setthecommunicationinbothcountriesto0.SettheBotchedVaccinesinDistrictAtotheleftmostLessSevereSetting.Advancethesimulationtotheend.Thisiswhatyoushouldseeonthescreen.

Atapproximatelywhattimedoesthepeakoftheinfectionoccur?4.5monthsWhatisthemaximumvaccinationincoverageinDistrictBatthetimeofthepeakoftheinfection?(Sincethelinesarequiteclosetogether,youmayusetheDistrictA’sestimateforDistrictBifyouareunabletohoverovertheDistrictBcurve).

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

~.49coverage3.SettheBotchedVaccinesslidertotherightmostsideortheMostSevereSetting.Keeptheinfluenceinbothcountriesat0.Thisiswhatyoushouldsee.Advancethesimulationtotheend.

WhatisthecoverageinDistrictBatthepeakoftheinfection?~.47NotetoInstructors:ItisveryimportantthatusersseethatthereisadecreaseincoverageinDistrictB!Youshouldbeseeingadecreaseincoverage.Ifnotjustplayaroundwiththetooltipuntilyoudo.Explainthedecreaseincoverage.Usethemodeltohelpyourreasoning.IfthemeaslescampaigninDistrictAisreallybotched,thenitbecomeslessacceptabletovaccinatechildren.Withacceptabilitydecreasing,fewerchildrenwillbevaccinated,andmorechildreninDistrictAwillbeinfected.AstheacceptabilityinDistrictBisinfluencedbytheacceptabilityinDistrictA,theacceptabilitywillalsotakeahitinDistrictB.Thisiswhyatthepeakofinfectionthecoverageisslightlylower.Thepurposeofthissimulationistounderstandthatthenewsofabotchedmeaslescampaigncanaffectthewillingnessofparentstovaccinatetheirchildren.4.NowchoosetheintensityofthebotchedvaccinesinDistrictA.Asyouadvancethesimulation,changetheinfluenceinDistrictB.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

Ifyouinducepositivecommunication,howwillthisaffectcoverageinDistrictB?Ifyoutakeawayinducenegativecommunication,howwillthisaffectcoverageinDistrictB?UserswillbeabletoseethatpositiveinfluenceshouldbringupthecoveragedespitewhatishappeninginDistrictA.Thisisbecausewecanbuyacceptabilityinasense.Wearetellingparentsignorewhatishappening,andfocusonthegoodofvaccines.Wecanalsobuynegativeacceptabilityandcontinuetoshowparentsthatvaccinesarenotgood.Thiswouldbringthecoveragedown.HowdoeschangingtheinfluenceinDistrictAaffectthecoverageinDistrictB?UserswillseeastheyincorporatenegativeinfluenceinDistrictA,theDistrictBcoveragewillgodown.UserswillseethatastheyincorporatepositiveinfluenceinDistrictA,thecoveragewillincrease.Withthesevisualizations,wherewouldyouallocatemoneytoimprovevaccinecoverageinDistrictB?Inotherwords,doyouthinkitismoreeffectivetoputmoneyintoinfluenceinDistrictAorintoDistrictB?Howwouldyouarriveatthedecision?Thisisuptotheuser.Instructorsneedtostressthatwewanttoputourmoneyintowherewethinkwewillseethelargestpositiveeffect.Whatareyourfinalthoughtsonthissimulation?Letusersusethisspacetowritedownanyburningquestionsorthoughtthatcanbediscussedlaterasagroup.Nowlet’smovetothenextsimulation!

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

SIMULATION3:CensortheMedia1.Gotohttps://forio.com/simulate/smatta1/south-sudan-and-uganda. Thisiswhatyoushouldseeonyourscreen.

2.Nowresetthesimulation.Clickdonotcensormedia.Keepthebotchedvaccinesettingattheleftmostlessseveresetting.Keepbothcommunicationvariablessetto0.Advancetotheendofthesimulation.Thisiswhatyoushouldseeonthescreenwhenthesimulationfinishesrunning.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

3.Nowmaintainthesamesettingsasbefore(bothcommunicationsshouldbesettozero,lessseverebotchedvaccinecampaigninDistrictA)exceptthistime,censormedia.Advancetotheendofthesimulation.Thisiswhatyoushouldseeonyourscreen.

Noticethatthecurvesarefatherapartwhenwecensor.Whyisthisthecase?BesuretoexplainhowtheinfectedpopulationcurvesANDthevaccinecoveragecurveschange.Besuretoexplainwhythisalsomakessense.Thereismorespaceinbetweentheinfectedpopulationcurveswhenwecensorthemediaasopposedtowhenwedonot.Thismakessensebecausewhenwecensorthemedia,wearecuttingDistrictBofffromwhatishappeninginDistrictA.BecausetheyareunawareofthebotchedmeaslescampaigninDistrictA,theywillnotbeasopposedtoreceivingvaccinationsandsowewillnotseeaslargeofapeakintheinfectedchildrencurve.Asforthevaccinecoveragecurve,whenwecensorthemedia,againDistrictBunawareofwhatishappeninginSouthSudan.Assuch,thecoverageinDistrictBwillbehigherthanitisinDistrictAbecausethenewsofthebotchedmeaslescampaignisnotreachingDistrictBsotheywillnotexperienceachangeinthevaccinationcoverage.TheDistrictAcoveragethough,willfall.Becauseofthischange,weseeagapbetweenthetwocurves.4.Resetthesimulation.Nowincreasetheseveritytotherightmostsidesetting,mostsevere.Thecommunicationshouldbesetto0forbothdistricts.Censorthemedia.Advancethesimulationtotheend.Youshouldseethefollowingonyourscreen.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

5.Resetthesimulation.Nowkeepthesettingsthesameasaboveexceptdonotcensorthemedia.Thisiswhatyoushouldseeonyourscreen.

ComparethetwosetsofcurveswhentheseverityofthebotchedvaccinesinDistrictAisthemostsevere.Howdoestheseverityofthebotchedmeaslescampaignaffectthedistancebetweenthecurves?Thegapsagain,existbetweenthesecurvesisbecauseofcensoring.Therationaleisthesameasthepreviousquestion.Asthebotchedmeaslescampaignbecomesmoresevere,thedisparitybetweenthecoverageinDistrictAandDistrictBislessened.Thismakessensebecausewhilethecensoringislimitedtothemedia,migrantsforexamplearemovingintoDistrictBandthereisstillinformationspreading.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

6.Nowincreaseordecreasethecommunication&chancethecensorsettingsasyouadvancethroughdifferentsimulations.Whatdoyounotice?• Ifthemediaiscensored:

o Buyingpositiveinfluenceonlyfurtherbooststhecoverageo Negativeinfluencewilldecreasecoverageindependentlyofthebotched

measlescampaigninSouthSudan• Ifthemediaisnotcensored:

o BuyingpositiveinfluencewillhelpboostcoverageafterithasbeenaffectedbythenewsinSouthSudan

o NegativeinfluencewillfurtherbringthecoveragedownFinalQuestionsandThoughts:Iscensoringthemediaworthwhile?Doesithaveagreateffect?Instructor’sNote:Helptheparticipantthinkaboutthecostvs.thebenefitofcensoringthemedia.Asktheparticipant:whatmatters?Inotherwords,howinfluentialisthemediainUganda?Isthatthebestwaytocombatnegativeinformationsurroundingvaccinations?AccordingtothesimulationshowcanweachievethegreatestcoveragewhenthebotchedmeaslescampaigninDistrictAisverysevere?Ifyouhaveunlimitedresources?Ifyouhavelimitedresources?ThissimulationshowsthatweneedtocutoffthemediabecauseotherwisethebadnewswillspooktheUgandansandaffectcoverage.Withlimitedresources,youcanonlyaffectthepositiveinfluencetoalimitedcapacitywhereaswithunlimitedresourcesyoucaninsensepurchaseacceptabilityorratherpurchasepeople’swillingnesstoacceptandutilizethevaccine.HowdoyouthinkthoseinDistrictBwouldreactiftheylearnedthatthemediawascensored?Instructor’sNote:Haveparticipantstalkaboutthissotheycanlearndifferingperspectivesregardingcensoring.7.NowclickNextPageandproceedtothenextsimulation.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

SIMULATION4:PhilipsonintheDistricts1.Afterclickingthenextpagebutton,thisiswhatyoushouldseeonyourscreen.

2.Clicktheresetbutton.SelectPhilipson.Advancetotheendofthesimulation.Thisiswhatyoushouldseeonthescreen.

Popquiz:DescribethePhilipsoneffectinyourownwords.ThePhilipsoneffectispresentwhenparents’likelihoodofgettingtheirchildrenvaccinatedisdirectlyproportionaltotheprevalenceofthediseaseitself.WithoutthePhillipsoneffect,theparents’willingnessisnotbasedontheprevalenceofthedisease,butrathertheunderstandingthatreceivingavaccineisapositivesocialgood.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

3.Resetthesimulation.ClickNoPhillipson.Advancethesimulationtotheend.Thisiswhatyoushouldseeonthescreen.

DescribethedifferencesthatyouseeinvaccinecoverageasyouturnthePhilipsoneffectonandoff.WhenconsideringthePhilipsoneffect,thecoveragecurvesmoveinunisonwiththeinfectedcurves.Themorekidsthatareinfected,themorecoveragewewillsee.WhenthereisnotPhilipsoneffectweseethattheinfectedpopulationisnotthesoledriverofvaccinecoverage.4.Playaroundwiththissimulationandadjustthebotchedvaccineseverityandthecommunicationlevels.Describewhatyousee?Userswillseethatevenwhenbuyingpositiveinfluenceornegativeinfluence,underthepresenceofthePhilipsoneffect,thecoverageisnotinfluencedbytheacceptabilityortheparents’willingnesstovaccinatetheirchildren.Whatareyourfinalconclusions?Whatwouldyouliketoseemovingforward?Usethisspacetodiscussanynewand/orfinalthoughtyouhave.

Copyright 2018, The Johns Hopkins University and Teaching Vaccine Economics Everywhere.

WorksCited1. Weisstein,E.W.SIRModel.Availablefrom:

http://mathworld.wolfram.com/SIRModel.html.2. Geoffard,P.-Y.andT.Philipson,DiseaseEradication:PrivateversusPublic

Vaccination.TheAmericanEconomicReview,1997.87(1):p.222-230.