（英文）行业资料 WHO -Guidance on the prioritization of insecticide-treated nets in situations where resources are limited

Guidanceontheprioritization

ofinsecticide-treatednetsin

situationswhereresources

arelimited

CONTEXT

Inthecontextoflimitedresources,nationalmalariaprogrammesmayneedtodecideonhowtoprioritizeallWHO-recommendedinterventions(1).

Thisguidancedocumenthasbeendevelopedtosupportnationalmalariaprogrammesinprioritizationdecisions,specificallyonthedeploymentscopeandproductchoiceofinsecticide-treatednets(ITNs).ThisguidanceistobefollowedwhenprogrammesdonothavesufficientbudgettodeploythemosteffectiveITNstoallpopulationsatrisk.

ThisguidancedoesnotaddressdistributionchanneldecisionsorotherissuessuchasfrequencyofITNdistribution,nordoesitcovereverychoicethatanationalmalariaprogrammemayneedtomakeregardingITNs.Rather,thisguidanceisintendedtobeastartingpointfordiscussionanddecision-making.

RoutinedistributionofITNstovulnerablegroups,suchaspregnant

womenandchildrenunder5yearsofage,remainscritical.Itisstrongly recommendedthatthesedistributionchannelsaremaintainedinallareas, regardlessoftheplansforcampaigns.Thisguidancedocument,therefore, focusesonensuringcoverageofvulnerablegroupsasthefirststepandthenplanningforhigh-volume,intermittentmassITNdistributions.Whiletheterm“campaign”isusedthroughoutthisdocument,theguidanceisapplicabletootherhigh-volume,intermittentdeploymentapproaches,suchaslarge-scale schoolorcommunitydistributions.

Overthelastthreeyears,morethan50%ofnationalmalariaprogrammeshaveimplementedamasscampaignwithtwoormoreITNtypes(i.e.pyrethroid-only,pyrethroid-piperonylbutoxide[PBO],pyrethroid-chlorfenapyrorpyrethroid-pyriproxifennets).TheITNtypeshavebeenbased,asfaraspossible,onlocalinsecticideresistancedataandtargetedtospecificgeographicalareas.Goingforward,increasingconstraintsinavailable

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resourcesduetoflatlinedfunding,highinflation,populationgrowthandcompetingprioritiesexertedbyothermalariainterventionsmayrequirenationalmalariaprogrammestomakeprioritizationdecisionsthatbalancenetquantitiesandtypes,distributionchannels,targetpopulationsandtherelativevalueformoneyofthesechoicesinordertooptimizeimpact.

ThisguidancedocumentaimsatsupportingprogrammesinthedevelopmentofaprioritizeddeploymentplanthatbalanceseffortstooptimizeITNeffectivenesswiththeneedtoensurecoverageofthemostat-riskpopulations.TheproposedprioritizationprocessisbasedonbestpracticesgeneratedinAfricainrecentyearsbutcanbeusedbyallcountriesdeployingITNs.

Tosummarize,theguidanceestablishesthisfirststep:

1.Ensureaccessforvulnerablegroups:commitfundingforroutineITNdistributiontovulnerablegroupsinallmalariariskareas.

Then,thedocumentguidesprogrammesthroughthefollowingstepsforcampaigndeploymentplanning:

2.DefinescopeofITNdeployment.

•Identifyandexcludeareaswithverylowcurrentandhistoricalmalariarisk.

•ListandranktheareastargetedforITNcampaignsaccordingtomalariarisk.

3.MaximizecoverageinareasidentifiedforITNdeployment:calculatethefundingneededtoensurefullcoveragewithpyrethroid-onlynets.

Iffundingremains:

4.Maximizeeffectiveness:substitutepyrethroid-onlyITNs(or,whereapplicable,pyrethroid-pyriproxyfennets)withpyrethroid-PBOorpyrethroid-chlorfenapyrITNsinareasofpyrethroidresistanceby:i)replacingpyrethroid-PBOorpyrethroid-chlorfenapyrnetsinareasthatpreviouslyreceivedthem,andii)substitutingpyrethroid-onlyITNswithpyrethroid-PBOorpyrethroid-chlorfenapyrITNsinadditionalgeographicalareasindecreasingorderofmalariarisk.

5.Identifyfundinggapsthatimpedefurthereffectivecoverageandmakethatinformationavailabletopotentialfunders.

6.Ensureadequatefundingforsurveillance.

STEP1.CommitfundingforroutineITNdistributionto

vulnerablegroupsinallmalariariskareas

•CalculatetheITNneedsforcontinuingroutineITNdeploymenttovulnerablegroups(e.g.pregnantwomenandchildrenunder5yearsofagethroughantenatalcareandExpandedProgrammeonImmunizationdistributions).Calculatetherequiredfundingforpyrethroid-onlynetsatthisstep.Fundingpermitting,thesenetscanbe“upgraded”tomoreeffectivenets,areabyarea,atlaterstepsintheprioritizationprocessinlinewiththeallocationofmoreeffectivenetstogeographicalareasforcampaigndeployment.Alternatively,programmes

mayhavealreadydecidedtousepyrethroid-PBOorpyrethroid-chlorfenapyrnetsthroughoutthecountryforroutinedistribution,inwhichcasethefundingrequiredtomeettheseneedsshouldbecalculatedhere.

Then,programmesshouldmovetocampaignplanning.

STEP2.DefineITNdeploymentscope

2a.Identifyandexcludeareaswithverylowcurrentandhistoricalmalariarisk

•Identifyareaswherethecurrentandhistoricalriskofmalariaisverylowbasedonnationalprogrammedata(includingmosturbanareas).InAfrica,verylow-riskareas(e.g.arangeof1–3%malariaprevalence)aregenerallyfoundinhighlyurbanizedcentresorinspecificruralareas;theidentificationof“verylow-risk”areasshouldconsiderthecomplexitiesbelow:

•Inlargetownsandcities,malariatransmissionisoftenheterogeneous,andhotspotsoftransmissionmayexist.Identifyanysuchareasofhigherlocaltransmission(i.e.excludinghotspotslinkedtoimportedcases)andensurethatthesearenotclassifiedas“lowrisk”(asexplainedintheGlobalframeworkfortheresponsetomalariainurbanareas(2)).

•TheinvasivevectorAnophelesstephensiisbeingreportedinanincreasingnumberoflocations,includingurbanareas.Toeffectivelycontrolthisvector,urbanareasthathavebeeninvadedbyAn.stephensiwillrequiresomeformofvectorcontrol.Dependingonthecontext,thiscouldincludeITNdistribution.

•Inruralareas,verylow-riskareasareonlyfoundatveryhighaltitudes,indesertsorattheedgeofmalaria’sgeographicaldistributionormaybetheresultofintensivemalariacontrolefforts.Alternatively,thereceptivityoftheseregionsmayhavechangedduetootheractivities,suchasirrigation,mining,infrastructuredevelopmentandclimatechange.Itis,therefore,criticaltolookatrecentandhistoricalepidemiologicaltrendstodeterminewhetheranareaisverylowriskformalariaandwouldremainsointheabsenceofITNs,whichwouldjustifythedeprioritizationofthearea.

•UsedatafromtheBreakthroughACTIONandVectorWorksITNaccessandusereport,inadditiontootherdata,tosupportdecision-makingonITNcampaignprioritization(3).Forexample,considerwhetherITNsmaybemoreeffectiveinurbanareasthanothervectorcontrolinterventions.

•UsethisanalysistodetermineareastobeexcludedfromcampaignITNdeployment,consideringthefollowingguidance:

•CeasecampaignITNdistributioninareaswithhistoricalandcurrentverylowrisk.

•CeasecampaignITNdistributioninareaswithdocumentedlowITNuse,unlessactiontosignificantlyincreaseusagehasbeenidentifiedandtheseactivitieshavebeenincludedinthevectorcontrolbudget.

•MaintainITNdistributioninareaswithpersistentlyhighormoderatemalariarisk,includingurbanclustersofmoderatetohighlocaltransmission.

•MaintainITNdistributioninareasthatarecurrentlylowriskbutwerehistoricallymoderateorhighrisk(i.e.lowriskhasonlyrecentlybeenachievedthroughvectorcontrol).

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•MaintainITNdistributioninareaswithhistoricallylowrisk,butwhereriskisincreasingduetoclimatechangeorotherfactors.

AfterappraisingvectorcontroloptionsforAn.stephensi,considerwhetherITNdistributioninareaswhereAn.stephensihasbeendetectedshouldbemaintainedorwhetheralternatives,suchaslarvalsourcemanagement,wouldbemorecost-effective.Thisdecisionshouldnotbeaffectedbyhistorical/currentmalariarisk.

Note:InareaswhereITNsarescaledbackduetolowmalariarisk,itiscriticaltoensurethatrobustsurveillanceisinplacetodetectepidemicsandthatthereisadequateaccesstocasemanagement.AdditionalinformationcanbefoundinboththeWHOguidelinesformalaria1andtheGlobalframeworkfortheresponsetomalariainurbanareas(2).

2b.ListandranktheareasforcampaignITNdeploymentinorderofmalariarisk

•DividethecountryintothelowestadministrativelevelsatwhichdifferentITN

typescouldfeasiblybedeployed(i.e.districtsorothersecond-leveladministrativeareas).Prioritizationstepswillconsidermalariarisk;therefore,atthisstage,itisbettertoconsiderthesmallestpracticalimplementationareas(e.g.districtsratherthanprovinces),assmallerareasaremorelikelytohavesimilarlevelsofmalariarisk.Epidemiologicaldataplusothercontextualfactors,suchasaccesstocare,shouldbeconsideredtohelpdefinerisk.

•Ranktheseareasbymalariarisk:

•Theaimistoassessthepotentialfortransmissionintheabsenceofvectorcontrol,especiallytheexpectedconsequencesifITNsarenotprovided.Malariaprogrammesshouldusethebestavailableindicatorsanddata,andtriangulatebothcurrentandhistoricaldata,includingprevalenceofinfection

insurveys,incidenceofclinicalmalariainhealthfacilities,transmissionintensity(fromentomologicalstudies),othercontextualfactors,andthebestestimatesofwellinformedandexperiencedstaff.

•Oneapproachwouldbetodraftaninitialrankingbasedonanassessmentofhistorical(i.e.pre-interventionornatural)transmissionintensity.Notethatinareaswherevectorcontrolcoverageiscurrentlymoderateorhigh,currentlevelsofmalariaincidenceandprevalenceshouldnotbeconsideredareliableindicatorofhistorical/naturaltransmissionintensity.Inareaswithlowburdenduetovectorcontrol,theimmunityinthepopulationmaybediminishedand,ifvectorcontroliswithdrawn,resurgence/epidemicsmayoccur.

•Oncetheinitialrankingbasedonhistoricalendemicityorbackgroundtransmissionintensityhasbeendrawnup,itwillthenneedtobeadjustedtoaccountforadditionalriskfactors.

•Foreachlocation,calculatehowmanynetswouldbeneededforfullcampaigncoverage(withaquantificationratioofonenetforevery1.8personsoramodifiedratiobasedonlocaldata).ProgrammesplanningtoalignthetypeofITNsintheirroutinedistributionsystemwiththetypeusedforcampaigndeploymentshouldincludeanadditionalcolumnstatingthenumberofnetsandassociatedfundingrequiredforroutinedistributionineachareaoveraperiodofthreeyears.

1Seethegoodpracticestatement“Noscale-backinareaswithongoinglocalmalariatransmission(2019)”

(1).

STEP3.Maximizecoverage:calculatethefundingneeded

toensurefullcoverageoftheseat-riskareaswith

pyrethroid-onlynets

•Forthepointsbelow,usethecostofapyrethroid-onlyITNandincludedeploymentcosts:

•Startingwiththeareawiththehighestrisk,assigntheresourcesneededforfullITNcoveragewithpyrethroid-onlyITNs.

•Continuetoassignresourcesdownthelistinorderofmalariarisk.

•Continueuntiltheavailablefundinghasbeendepleted.(Itisbesttoendonacompletelycoveredarea,ratherthanonahalf-coveredarea,whichwouldcreateoperationaldifficulties).

IfresourcesremainafterStep3,movetoStep4.Ifnot,gotoStep5.

STEP4.Maximizeeffectiveness:substitutepyrethroid-

onlyITNswithpyrethroid-PBOorpyrethroid-

chlorfenapyrITNsinareasofpyrethroidresistance

asfaraspossible

•ConsiderwhichareasinyourITNdeploymentplanhavepyrethroidresistance.Ideally,theseareaswillbeprovidedwithpyrethroid-PBOorpyrethroid-chlorfenapyrITNsfollowingtheprocessesinsteps4aand4b.Recognizingthatnoprogrammeislikelytohaveinsecticideresistancedataforalldeploymentareas,someextrapolationfromadjacentareasisappropriate,includingfromadjacentareasofneighbouringcountrieswhererelevant.

•Allocatetheresourcesremainingafterstep3tosubstitutepyrethroid-onlyITNsinthedeploymentplaninthefollowingsteppedprocess.

•Notethat,basedontherecentWHOrecommendationonpyrethroid-pyriproxifennets,thecurrentlyhigherprocurementcostandtheirlowgeographicalcoverage/numberdistributedtodate,thesetypesofnetsarenotexplicitlyincludedin

thisprioritizationguidancewhichfocusesspecificallyoncontextsofinsufficientresources.Insuchsettings,countriesshouldconsiderdistributionofpyrethroid-PBOorpyrethroid-chlorfenapyrnetsinareasthatwerepreviouslycoveredbypyrethroid-pyriproxifennetswhentheopportunityarises.

•Fortheprocessbelow,considertheincrementalcosttosubstitutepyrethroid-onlyITNswithpyrethroid-PBOorpyrethroid-chlorfenapyrITNs,notingthatthecostsofdeployingITNstoendusershavealreadybeenaccountedforinsteps1and3above.

4a.Replacepyrethroid-PBOorpyrethroid-chlorfenapyrnetsinareasthatpreviouslyreceivedthem

•Allocatetheadditionalavailableresourcesneededtoreplacepyrethroid-PBOorpyrethroid-chlorfenapyrITNsinareasthatpreviouslyreceivedthesenettypes,startingfromtheareaswiththehighestrisk.ProgrammesplanningtoalignthetypeofITNsintheirroutinedistributionsystemwiththeircampaigndeployment

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planshouldallocatetheadditionalresourcesneededtosubstitutethepyrethroid-onlyITNsforroutinedistributionwiththenettypetobeusedforthecampaign.

•Continueareabyareauntilresourcesaredepleted.Ifresourcesremainafterstep4a,movetostep4b.Ifnot,gotoStep5.

4b.Substitutepyrethroid-onlyITNswithmoreeffectiveITNsinadditionalareasindecreasingorderofmalariarisk

•Allocatetheadditionalresourcesneededtosubstitutepyrethroid-onlyITNswithpyrethroid-PBOorpyrethroid-chlorfenapyrITNsinadditionalareas,startingwiththenexthighestriskareaswithpyrethroidresistanceandexpandingtoneighbouringhigh-riskdistrictswithoutpyrethroidresistancedata.

•ProgrammesplanningtoalignthetypeofITNsintheirroutinedistributionsystemwiththeircampaigndeploymentplanshouldallocatetheadditionalresourcesneededtosubstitutethepyrethroid-onlyITNsforroutinedistributionwiththenettypetobeusedforthecampaign.

Continueareabyareauntilresourcesaredepleted.

Step5.Identifyfundinggapsthatimpedefurthereffective

coverageandmakethatinformationavailableto

potentialfinancers

•IfprogrammescannotachieveoptimalcoverageeitherwithanyITNorwith

themosteffectiveITNwiththeavailablefunding(consideringallexternalanddomesticsources),thenaprioritizationexerciseamongallinterventionswillneedtobeconsidered.Ifgapspersist,theseadditionalfundingneedsshouldbeidentifiedandcodified,andthisinformationshouldbeprovidedtopotentialfinancers,suchasthegovernmentorthePresident’sMalariaInitiative,and/orincludedinaprioritizedaboveallocationrequesttotheGlobalFundtoFightAIDS,TuberculosisandMalaria.

STEP6.Ensureadequatefundingforsurveillance

•ArobustsurveillancesystemisneededtoensureappropriatemonitoringofmalariaindicatorsinordertoprovidetimelysignalsofpotentialresurgenceinareasnolongerreceivingITNs,aswellasforroutineprogrammaticdecision-making.Allocatesufficientfundingtoaddressanysurveillancestrengtheningandsystemmaintenanceneeds.

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METHODSANDACKNOWLEDGEMENTS

ThisguidancewasdevelopedalongsidenewWorldHealthOrganization(WHO)recommendationsondualactiveingredientITNs,withaviewtosupportingWHOMemberStatesinnationaldecision-makingprocessesonITNdeploymentintheincreasinglycomplexareaofmalariavectorcontrol.DraftprioritizationguidancewasdevelopedincollaborationwithmalariapartnersbroughttogetherbytheAllianceforMalariaPrevention(AMP)andtheRBMPartnershiptoEndMalaria.ThedraftguidancewaspresentedtotheWHOGuidelineDevelopmentGroup(GDG)formalariavectorcontrolcontentinNovember2022andtotheassociatedEvidenceReviewGroup(ERG)inJanuary2023fortheirreviewandinputs.WHO’soriginalintentionwastoincludethisguidancealongsidethenewITNrecommendationsintheWHOGuidelinesformalaria;however,itwaseventuallydecidedthatthelevelofdetailofthisguidanceexceedsthatoftheGuidelinesanditshouldbepublishedseparately.Declarationsofanycompetinginterests(DOIs)werereceivedfromallinvitedexpertsoftheGDGandERG.WHOprocesseswereusedtoassessthedeclaredinterestsandmanageanyconflictsidentified.ThreemembersoftheGDGdeclaredpotentialinterests.BasedonthedetailedassessmentoftheinformationprovidedtoWHO,theinterestsofonememberweredeemednotrelevant,whilethoseoftwomembersweredeemedrelevant;thesetwomemberswererecusedfromthedecision-makingprocessesandreviewsofrecommendationsregardingdualactiveingredientITNs.FivemembersoftheERGdeclaredpotentiali