Opportunities and challenges of Web 2.0 for vaccination decisions

Opportunities and challenges of Web 2.0 for vaccination decisions ^q

Cornelia Betsch

, Noel T. Brewer

, Pauline Brocard

, Patrick Davies

, Wolfgang Gaissmaier

,

Niels Haase

, Julie Leask

, Frank Renkewitz

, Britta Renner

, Valerie F. Reyna

, Constanze Rossmann

, Katharina Sachse

, Alexander Schachinger

, Michael Siegrist

, Marybelle Stryk

aUniversityofErfurt,Germany

bDepartmentofHealthBehaviorandHealthEducation,GillingsSchoolofGlobalPublicHealth,andLinebergerComprehensiveCancerCenter,UniversityofNorthCarolina,Chapel Hill,UnitedStates

cLondonSchoolofHygieneandTropicalMedicine,UnitedKingdom

dPaediatricIntensiveCareUnit,NottinghamChildren’sHospital,Nottingham,UnitedKingdom

eHardingCenterforRiskLiteracy,MaxPlanckInstituteforHumanDevelopment,Berlin,Germany

fNationalCentreforImmunisationResearch&Surveillance,DisciplineofPaediatricsandChildHealthandSchoolofPublicHealth,UniversityofSydney,Australia

gDepartmentofPsychology,UniversityofKonstanz,Germany

hCenterforBehavioralEconomicsandDecisionResearch,DepartmentsofHumanandPsychology,CornellUniversity,Ithaca,NewYork,UnitedStates

iInstitutfürKommunikationswissenschaftundMedienforschung,MunichCenterofHealthSciences,Ludwig-Maximians-UniversitätMünchen,Germany

jDepartmentofPsychologyandErgonomics,TechnischeUniversitätBerlin,Germany

kHumboldtUniversityofBerlin,Germany

lInstituteforEnvironmentalDecisions(IED),ETHZurich,Switzerland

mEuropeanCentreforDiseasePreventionandControl,Stockholm,Sweden

Keywords:

Internet Web2.0 Anti-vaccination Riskcommunication

a b s t r a c t

AgrowingnumberofpeopleusetheInternettoobtainhealthinformation,includinginformationabout vaccines.Websitesthatallowandpromoteinteractionamongusersareanincreasinglypopularsource ofhealthinformation.Usersofsuchso-calledWeb2.0applications(e.g.socialmedia),whilestillin theminority,representagrowingproportionofonlinecommunicators,includingvocalandactiveanti- vaccinationgroupsaswellaspublichealthcommunicators.Inthispaper,theauthors:defineWeb2.0 andexaminehowitmayinfluencevaccinationdecisions;discusshowanti-vaccinationmovementsuse Web2.0aswellasthechallengesWeb2.0holdsforpublichealthcommunicators;describethetypes ofinformationusedinthesedifferentsettings;introducethetheoreticalbackgroundthatcanbeused todesigneffectivevaccinationcommunicationinaWeb2.0environment;makerecommendationsfor practiceandposeopenquestionsforfutureresearch.Theauthorsconcludethat,asaresultoftheInternet andWeb2.0,privateandpublicconcernssurroundingvaccinationshavethepotentialtovirallyspread acrosstheglobeinaquick,efficientandvividmanner.Web2.0mayinfluencevaccinationdecisionsby deliveringinformationthatalterstheperceivedpersonalriskofvaccine-preventablediseasesorvaccina- tionside-effects.Itappearsusefulforpublichealthofficialstoputeffortintoincreasingtheeffectiveness ofexistingcommunicationbyimplementinginteractive,customizedcommunication.Akeysteptopro- vidingsuccessfulpublichealthcommunicationistoidentifythosewhoareparticularlyvulnerableto findingandusingunreliableandmisleadinginformation.Thus,itappearsworthwhilethatpublichealth websitesstrivetobeeasytofind,easytouse,attractiveinitspresentationandreadilyprovidetheinfor- mation,supportandadvicethatthesearcherislookingfor.Thisholdsespeciallywhenlessknowledgeable individualsareinneedofreliableinformationaboutvaccinationrisksandbenefits.

A growing number of people use the Internet to obtain health information, including information about vaccines [1–4]

q Disclaimer:Thestatementsarethepersonalviewsoftheauthorsanddonot necessarilyconformtotheviewsoftheauthors’organizations.

∗Correspondingauthorat:Center forEmpiricalResearchinEconomicsand BehavioralSciences(CEREB),UniversityofErfurt,NordhäuserStrasse63,D-99089 Erfurt,Germany.Tel.:+493617371631.

E-mailaddress:cornelia.betsch@uni-erfurt.de(C.Betsch).

obtained from different sources: both public health communi- catorsaswellasorganizedanti-vaccinationgroupsdisseminate information related to vaccinations [5]. Furthermore, websites that allow and promote interaction among users are a source of health information that is growing in popularity. Users of such so-called Web 2.0 applications (e.g. social media), while still in the minority, represent a growing proportion of onlinecommunicators,includingvocalandactiveanti-vaccination groups.

Konstanzer Online-Publikations-System (KOPS) URL: http://nbn-resolving.de/urn:nbn:de:bsz:352-206963

In this paper, we¹: define Web 2.0;examine how Web 2.0 mayinfluencevaccinationdecisions;discusshowanti-vaccination movementsuseWeb2.0aswellasthechallengesWeb2.0holds forpublichealthcommunicators;describethetypesofinforma- tionusedindifferentsettings;introduceatheoreticalbackground thatcanaiddesigningvaccinationcommunicationinaWeb2.0 environment;makerecommendationsforpractice;andposeopen questionsforfutureresearch.

1. DefiningWeb2.0

WedefineWeb2.0asInternetapplicationsthatenableusersto createanduploadnewcontent,commentonexistingcontentand sharecontentwithotherusers[6],e.g.discussionboards,webblogs andsocialmediawebsitessuchasFacebook,Twitter,Wikipedia, LinkedInandYouTube.Thatis,while‘Web1.0’Internetwebsites typicallyallowedforone-waycommunicationfromthecreatorof thesite totheuser(e.g.statichealthportals), Web2.0enables two-wayandmulti-waycommunication[6–8].Web2.0applica- tionsreducemajortechnicalbarrierstofacilitateinteractionswith otherusers.Social media,forexample,provideopportunitiesto publiclyexpresssupportforanissueandforwardinformationto friendswithoutgreateffort(e.g.‘like’buttoninFacebook,‘retweet- ing’inTwitter).Existinginformationcanbere-used,modifiedand addedtogrowingdatabasesofcrowd-sourcedknowledge[7].This technologicalprogressblursthelinesbetweenthereceptionand productionofmediacontent[8,9].

Meta-analysesshowthatmass-mediatedhealthandriskmes- sagescanraiseawarenessregardinghealthissuesaswellas,toa morelimitedextent,influenceindividuals’perceptions,attitudes, behaviorintentionsandbehavior[10,11].Forthepurposeofhealth promotion,healthscholarsseegreatpotentialintheuseofonline communicationand,toagrowingextent,alsoWeb2.0-applications forseveralreasons[12].Duetotheirhybridcharacter,socialmedia combinethereachoftraditionalmassmediawiththeinteractivity anddynamismofinterpersonalcommunication,thuspotentially increasingtheireffectiveness[12–14].Byactivelycreatinganddis- seminatinginformation, users become moreinvolved, which is assumedto amplifypotentialeffectsof information onpercep- tions,attitudesand behavior[15–17].Web2.0healthmessages alsohave thepotentialtoreachalargeaudiencethroughrapid electronicword-of-mouth,which can growexponentially (viral marketing[18]).Importantly,suchmessagesaredisseminatedby individualswhouserslike,trust,and/orknow.Forexample,Twit- terfollowersmayadmirethosewhomtheyfolloworviewthem asopinionleaders[19,20].Knownandtrustedsourcesaremore likelytoshapebeliefs,attitudes,andbehavior[19,20].Finally,the Internetprovidesagoodplatformfortailoredhealthcommunica- tion[21]:Whenusersenteratailoredwebsite,theyfirstcompletea questionnaireassessingcentralpersonalcharacteristicsrelevantto specifichealthbehaviors.Then,usersreceivemessagesspecifically tailoredtotheirpersonalneeds.Evaluationsindicatethattailored healthcommunicationhasasmallbutreliableeffectonuserhealth behavior[22].

In thispaper,wefocusonthreedifferentactorsin Web2.0:

1)thedecisionmaker(referredtoastheuser)asthereceiverof informationobtainedontheInternet;2)health-communicators whouseWeb2.0todisseminateevidence-basedfactsaboutvac- cinationaswellasmessagesprovidingsupportforrecommended

1Thequestionswerediscussedduringthe2½-dayconference“Risk2.0–Riskper- ceptionandcommunicationregardingvaccinationdecisionsintheageofWeb2.0”

inErfurt,GermanyinMay2011.Allauthorsofthispaperparticipatedinthemeeting.

Thispublicationoutlinesthediscussionandtheconsensusthatwasreachedduring themeeting.

vaccinations,e.g.viasocialmedia(suchastheCentersforDisease Preventionand Control(CDC));and3)anti-vaccinationactivists whouseWeb2.0todisseminatemessages,factsandbeliefsthat opposesomeorallrecommendedvaccinations[23–28].

2. HowmayWeb2.0influencevaccinationdecisions?

Vaccinationdecisionsaremadeonacomplexarrayoffactors includingdoctor’srecommendation,socialnorms,previousexpe- riences,trustinindividualsandorganizationsandothercognitions.

Thesefactorsmostlyworkinfavorofvaccinating.However,there areconcerns thatworriesaboutvaccines maybegrowing[29].

Hence,understandingdecisionprocessesisimportant.Thesecan bedescribedasoccurringinthreestages[30].Inthepre-decisional phase,individualsconsidertheiroptions,usuallytoeithervacci- natewithintherecommendedtimeframe,withdelayornotatall.

Whilemostindividualstrusttheofficialvaccinationrecommen- dations[31,32],individualsmaystillseekadditionalinformation duringthisphase,e.g.byconsultingtheeasilyaccessibleInternet [4,33].

Individualsinthedecisionalphasethenevaluatepotentialout- comesof alternativeactions(such asvaccinating or not)based ontheobtainedinformation.Currenttheoriesofhealthbehavior assumethatindividualsmustfirstperceivethemselvesasbeingat riskbeforetheywilltakeprotectiveaction[34,35].Thus,theper- ceivedriskofcontractingthevaccine-preventablediseaseaswellas theperceivedriskofvaccineadverseeventsrepresentcorepredic- torsofvaccinationintentions[28,36–40].Riskperceptionhasbeen conceptualizedasacombinationofone’sbeliefsaboutthelikeli- hoodofbeingaffectedbyanegativeevent(e.g.,contractingHPV) andtheseverityofthenegativeevent(e.g.,cervicalcancercanbe lethal[41]).This‘riskasanalysis’viewhasbeencomplemented withthe intuitivesensing of risk:the ‘riskas feeling’ perspec- tive([42] or‘affect heuristic’[43])holds thatrisk perceptionis basedonaffectivestimulusevaluations[44,45],which formthe basisofauthenticexperiencesofriskasopposedtocognitiveinfer- ences.Thus,anyinformationobtainedduringpre-decisionalonline researchthatalterseithertypeofperceivedpersonalriskshould affectvaccinationintentionsinthedecisionalphase.

Initially,individualsmayperceivethemselvestohavealowrisk ofcontractingavaccine-preventabledisease,astheincidencerates ofvaccine-preventablediseasesarelowduetothesuccessofvac- cinations.Asfewindividualshavefirstorsecond-handexperience withvaccine-preventablediseases,theylackvividrepresentations ofdiseaserisk.Inaddition,thebenefitsofvaccinationariseinthe futureandarethustypicallyintangibletoindividualsatthetime ofthedecision,especiallysincetheyrefertoaneventthatwillnot occur,i.e.notcontractingadisease.Further,individualsalsobenefit whenothersgetvaccinatedandherd-immunityincreases,which makesfree-ridingattractive[46].Contrarytothesocietalbenefit, theindividualbenefitbecomessmallerasmorepeoplegetvacci- nated.Vaccinationsmayalsobefollowedbyadverseeventsthatare eithercorrectlyorfalselyattributedtothem(e.g.,causallyestab- lishedoutcomessuchasanaphylaxisordisprovenoutcomessuch asautism[47,48].Individualsmayfinditeasiertovisualizethat vaccinationsareharmful,especiallysincesuchlinksaresuggested by vivid anti-vaccination messages and possess face-value bio- logicalplausibility[49].Giventhatanti-vaccinationwebsitesand theemotion-elicitingmaterialstheyhostarereadilyavailable(see below),individualsmayperceiveagreaterriskofsufferingfrom vaccinationside-effectsthanofcontractingavaccine-preventable disease.

In thepost-decisionalphase,individuals again receive imbal- ancedfeedbackregardingtheirdecision:whilevaccinationcosts such as pain, time, money and potential adverse events are

immediateandtangible,thebenefitsaretypicallydelayedorless tangible.Aswithalltypesofprevention,thedifficultywithvac- cinationsisthatindividualscanneverknowwhethertheywould havecontractedthediseasehadtheynotbeenvaccinated –the preventionisunobservable.Incontrast,adverseeventsareeasily connectedtothevaccination,eventhosethatareactuallyunrelated andwouldhaveoccurredanyway[47,50].Vaccinationexperiences mightbeeventuallypublishedbyindividualsontheInternet(e.g.

asadvicetootherusersorintheformofstoriesabout(alleged)side effects),thusmakingtheuseraproducerofvaccinationinforma- tion,aswell.

3. OnlinevaccinationinformationintheeraofWeb2.0

Asmanyas72%ofAmericanuserstrusthealthinformationthey obtainontheInternet[51].Also,around75%ofAmericanusers evaluatethesourceandstatusofonlinehealthinformationonly sometimes,hardlyeverornever[52].Informationavailableonthe WorldWideWebcanbemorereliable,accurateandup-to-date thanthatfoundinprinted brochuresorprintedencyclopaedias, e.g.becausepublichealth agenciesincreasinglyinvestinonline publications or due to theso-called wisdom of the crowd phe- nomenon(i.e.heterogeneouscontributorscollaborativelyproduce highqualitycontentinanopenenvironment,suchasWikipedia;

[53,54]).However,substantialmisinformationisalsowidelyavail- able,especially onanti-vaccinationwebsites [24,55,56].Further, lotsof importantinformation is missing when individuals con- duct web searches:A recent study showedthat approximately onethird of websites obtainedin a Googlesearch ontherela- tionbetweenautismandtheMMRvaccinationdonotcontainkey informationregardingtheabsenceofalinkbetweenautismand vaccinationsandaboutaquarterofwebsites containinaccurate information[57].Inanotherstudy,websitesprovidedcorrectinfor- mationregardingthequestionsofwhetherthedosesofvaccine additivesweredangerous,whetherchronicdiseasesaretriggered byvaccinesandwhethervaccinespromoteallergiesinonly58%, 53%and34%ofthewebsites,respectively[58].

Recent research has identified characteristics that could increaseusers’vulnerabilitytoobtainnon-reliableinformationin Internetsearches:lowersocioeconomicstatus[59,60],lowercog- nitiveabilityandolderage[61],lowerliteracyorhealthliteracy (theabilitytoreadandunderstandwrittenorverbal(health)infor- mation[62]), less understandingof howto searchthe Internet (i.e.,digitalliteracy[63,64]),lessknowledgeaboutvaccination[65]

andlowernumeracy(theabilitytounderstandandusenumbers [66]).Thus,whiletrustinonlineinformationappearstobehigh, retrievalofreliableinformationdependsontheaccessedsources andindividualfactors.Theremainderofthissectiondiscussestwo differentsourcesofvaccineinformation:anti-vaccinationactivists withafocusontheireffortsinWeb2.0utilization;andpublichealth communicatorsandthechallengestheyface.

3.1. Anti-vaccinationactivists’Web2.0efforts

Opposition to vaccination has existed since the practice first began [67–69]. In recent years, the Internet has provided well-organizedanti-vaccination groups with a rapidly growing internationalforumfor communicating,networking andcoordi- nating lobbying efforts. Many such groups have websites that placeenormousweightonadverseevents–bothestablishedand allegedsideeffects[23,24,70].Largeranti-vaccinationgroups(e.g.

NationalVaccineInformationCenter,AustralianVaccinationNet- work)alsoactivelyuseWeb2.0bycoordinatingtheirpresencein onlinepollsandonparentingdiscussionboards,Twitter,Facebook andYouTube[25,71,72].Thisincreasestheavailabilityofmaterial

opposingvaccinationthatisoftenvivid,emotionallyarousingand personal.Ascohortsofwell-connecteddigitalnatives(individuals whogrewupwithdigitaltechnology[4,73])becomeparents,anti- vaccinationinformationmayreachaudiencesmorerapidlyandin anevengreatervolume.

Hobson-Westdescribedtwodistinctinterestgroups:reformists whoarecriticalofvaccines butlikelytoprovideatleastpartial supporttovaccination;andradicalswhofollowalternativenotions of health and question allvaccines [74]. Suchlobbying groups aretypicallyformedbyparents[75]becausethemajorityofvac- cines are receivedinchildhood and adolescence. Someparents basetheirallegianceonanexistinginterestinalternativetherapies andnaturalhealthpracticeswithanantipathytomedicalinter- vention.Otherspreviouslysupportedimmunizationbeforetheir childsufferedafrighteningyettemporaryadversereaction,such asprolongedcrying.Theseparentsspeakofdissatisfactionwiththe responseofhealthprofessionalstosuchincidentsandthenembark onphasesofquestioningandultimatelyrejectionofvaccinations [76,77].Afinalgroupincludesparentswhosechildrenaredisabled orsufferfromchronic,permanentandtypicallyunexplainedmed- icalconditionsthattheybelievetobearesultofvaccination.

Inaddition,country-specificandothercontextualissuesinflu- encepublicquestioning[77].Policychoicesorrecommendations, suchasthedecisioninFrancetowithdrawthehepatitisBvaccina- tionprogramfromschoolsandtheEuropeanMedicinesAgency’s recommendationtolimittheuseofacertainvaccinetopersons overtheageof20[78],alsopromptindividualstoquestionvac- cinesafety[79,80].Publicquestioningmayalsoemergefollowing thepublicationofnewresearch,suchasAndrewWakefield’snow discreditedresearchontheMMRvaccine[81,82].Finally,politi- calandsocio-culturalreasonsorbeliefsthatleadtosuspicionand conspiracytheories,suchasconcernssurroundingthepoliovacci- nationinIndiaandnorthernNigeria[83]orthecontroversyabout thesafetyoftheHPVvaccine(e.g.India[84]),mayalsoleadtothe publicquestioningofvaccination.

Vaccine-criticalWeb1.0websiteshavebeenrepeatedlyevalu- atedregardingtheircontent[23,24,85].Thesesitestypicallyargue thatvaccines causeillnesses ofunknownorigin(suchasmulti- plesclerosis,autism,asthmaandsuddeninfantdeathsyndrome), erode immunity, contain ingredients that endanger health and overwhelmchildren’simmunesystems,especiallywhenadmin- istered in combination². Narratives, i.e. reports of individuals allegedlyharmedby vaccines,areusedonthemajorityofsuch websites[24](seenextparagraphforextendeddiscussion).

3.2. Informationthataltersriskperceptionsandvaccination intentions:thepowerofnarratives

While scholars arereluctant torecommend theinclusion of narrativesindecisionaids[86,87],onlinedebatesaboutvaccina- tionarefilledwithpersonalstoriesofpatientsandparentswho describeinvividlanguagethehealthproblemstheybelieve(cor- rectlyorincorrectly)tobetheresultofvaccination.Asprevious analyses(suchas[24])explicitlyexcludeWeb2.0sites,theactual amountofavailablenarrativeinformationisprobablyevenlarger thanhasbeendocumentedtodate.Theperson-centeredtechnique ofWeb2.0’sinformation creationisparticularlywellsuitedfor collectinganddisseminatingpersonalstoriesinanti-vaccination messages.Hence,whilenarrativereportshavealwaysbeenpartof

2Publichealthorganizations(e.g.theGermanRobertKochInstitutewiththe Paul-EhrlichInstitute[56]andtheAustralianGovernment[125])havepublished online-documentsthatdocumentthesemythsandgiveeasytounderstandscientific evidenceagainstthem.

anti-vaccinationmessages,theirdisseminationhasgrownviathese media.

Narrativeshaveinherentadvantagesoverothercommunication formats[88].Narrativesofpurportedvaccinationinjuriesinclude allofthekey elementsof memorablemessages:Theyare easy to understand,concrete, credible in the way in which a first- personstoryofvictimizationisalwayscredible (“Iwasthere!”) andhighlyemotional.Thesequalitiesmakethistypeofinforma- tioncompelling;inriskysituations,individualsprefertoknowhow consequencesmightbeiftheydooccur,ratherthanhowlikelya consequenceistooccur[89].Moreover,whenparentsalreadyper- ceivehighvaccinationrisks,theyaremoreinclinedtosearchfor narrativereportsbyotherparentsontheInternet[90].Whetheror notthesestoriesrepresentverifiablevaccinationrisksisimmate- rial.Theexistenceofnarrativesaboutadverseeventsonwebsites increasestheperceivedriskofadverseevents,especiallyviathe elicitationof emotionalreactions[28]. Further,lab experiments showedthatthegreaterthenumberofnarrativesthatpeopleread, thehighertheperceptionofriskwas,regardlessoftheinformation containedinsimultaneouslypresentedstatisticalinformation[91].

Inadditiontobeingindividuallypersuasive,thebroaddistribu- tionofstoriesofperceivedvaccine-relatednegativeoutcomesvia theInternetdistortsusers’perceptionsoftheactuallikelihoodof suchevents.Individualsconsiderhowoftentheyseesuchnarra- tivesinordertoestimatehowoftendifferenteventswilloccurin reallife.Thus,ifindividualsobservetwopositiveandtwonegative narratives,manywillassumethatpositiveandnegativeeventsare equallylikelyintherealworld[92].Currently,however,negative narrativesaboutvaccinationsaremuchmorewidespreadonthe Internetthanpositivenarratives.Thus,whenindividualssample storiesavailableonline,theyaretypicallylikelytoperceivethatthe weightofexperientialevidenceisagainstvaccination,eventhough negativenarrativesdonotrepresenttheexperienceofalargenum- berofpeople.Additionally,asoutlinedearlier,narrativesmayelicit affectandemotionsaswellasimpactriskperceptionsviathedirect

‘riskasfeelings’link[28,42].This,inturn,maydecreaseindividuals’

intentionstovaccinate[91].

3.3. Web2.0challengesfor(Public)healthcommunicators

Publichealthagencieshavethegoalofdisseminatingdisease- related news, risk assessments, epidemiological updates and scientific publications. Public health communicators, therefore, provideinformation that is reliable and correct; however,it is usually alsomore complex, sothat it may require individuals’

substantialmotivationandefforttobeunderstandable[88].Schol- arsagree that efficient risk communicationshould becarefully designedfollowingevidence-basedprinciples(suchasoutlinedin [93]).

Aspublichealthagenciesincreasinglycomplementtheirtradi- tionalmediaofferswithWeb2.0tools(Twitter,Facebook,YouTube, Wikipedia,LinkedIn),efficientriskcommunicationisfacedwith severalnewchallenges.Onecommunicationobjectiveistotake advantageofsocialmedia’sreal-timeandrapiddisseminationfea- turesduringcrises(e.g.pandemicoutbreaks[94]orepidemicsof infectiousdiseasessuchasmeasles,E.coli).Onechallengethatpub- lichealthagenciesencounterwhenusingsocialmediaistokeepup withandreacttothisfastmovingmedium.Thischallengerequires clearcommunication strategies and guidelines (such as who is allowedtocommunicateofficialmessagesandwhattheyareper- mittedtosay).Languagebarriersrepresentanotherchallenge,not onlybetweencountriesbutalsointermsofthedifficultyofcom- municatingcomplicated scientificterms andfindings quicklyin comprehensible(andstillevidence-based)messagestothepublic –insomecaseseveninlessthan140characters(e.g.Twitter).

Adequatehealthmessagescontaintheinformationthatusers need,connectuserswiththatinformation,andareunderstoodby users[95].Healthmessagesthathaveachancetogoviral[18]must bememorableandinteresting;and theremust bea numberof wellconnectedpeople(socialhubs)thatisinitiallylargeenough tospreadthemessagetolargegroupsofotherpeople.Thus,the quandaryliesinrapidlycreatingadequateandeffectivemessages thatareevidence-based,bothregardingcontentanddesignofthe message.

3.4. Thedifficultywithnumbers

Howshouldonlineinformationbepresented?Ideally,medical informationshouldbebasedonthebestavailableclinicalevidence andtransparentlypresentstatisticalinformationaboutthebenefits andrisks[96,97].However,statisticalinformationthatnumerically documentstherarityofsideeffectsisusuallylessengagingthan apersonalstory,e.g.ofsomeonewhosuffereda presumedside effect[91].Furthermore,statisticalinformationcanalsobemore difficulttounderstand.Largeproportionsofthepopulationhave lownumeracy[66],includingotherwisewell-educatedindividuals andexperts.Furthermore,individualswithlowernumeracyhave distortedperceptionsoftherisksandbenefitsoftreatmentsandare morevulnerabletoframingeffects(see[66]forarecentreview).As aconsequence,suchindividualsaremorelikelytoignorenumerical informationandinsteadfocusonnarratives[98].

Variousresearchfindingsshowthat,formostindividuals,num- bers(demonstrating risk)are oftenperceivedasratherabstract information with only limited vividnessand experientialvalue [99,100]. In order to become relevant for protective behavior, abstractnumbersmustelicitperceivedthreat,worryandconcern [40,101],i.e.abstractnumbersmustbecome‘visceralmotivation’

[99,102,103].

Researchhasidentifiedwaysinwhichnumberscanbemade tomattertopeople.Thereare,forinstance,basicprinciplesfor hownumbersmustbepresentedinordertobeintuitivelyunder- standable[88,97,104,105].Additionally,graphicalrepresentations arepromisingtoolswithwhichtounderstandablyconveynumbers [106–112],inparticulartoindividualswithlownumeracy[113].

Someofthesemethodshavebeenusedinthevaccinationcon- text[114],e.g.indecisionaids[115,116],buttheirusecouldbe greatlyexpanded[117].Onemustbeaware,however,thatgraphi- caldisplaysarenotasilverbullet.Pastresearchsuggeststhatsome graphicalrepresentations,forexample,mightworkonlyforindi- vidualswithhighnumeracy[118,119].

4. Communicatinggist

Asdescribedabove,publichealthcommunicatorsarefacedwith recipients who have diverseprior knowledge, needsand abili- ties.Internetsearchesleadtopublichealthandanti-vaccination websiteswithaboutequallikelihood(10vs.11%;[58]),thusmak- ingpowerfulanti-vaccinationinformationasequallyavailableas scientific evidence that is reliable yet more difficult to under- stand.Howcanvaccinationcommunicationbeimprovedinsuch a situation?Howcanrisk perceptionsbedirectlyaddressedby professionalvaccinationcommunication?

Toensuretheeffectivenessofhealthmessages,theusermust understandthemessageinawaythatallowsforbothretention inmemoryand theavailability oftheknowledgeatthetimeof behaviorimplementation[120].Mostrecently,adual-processthe- orywasappliedtoriskperception,communication,anddecision making:fuzzy-tracetheory[88,120–123].Accordingtothistheory, individualsintegrateinformationintomemoryintwoways:Ver- batimmemoriesincludeallprecisedetails,whereasgistmemories

containonlythebasicmeaning.Decisionstendtobebasedongist memories–orthebasicmeaning–notverbatimfacts.According tothistheory,therefore,websitesthatproducemorecoherentand meaningfulgistwillbemoreinfluential.Asarecentstudyshowed, anti-vaccinationwebsiteswereperceivedasmorecoherentthan websitesfromtheCentersforDiseaseControl[65].Thismayfacil- itateretentionoftheinformationinmemoryandfostertheuseof anti-vaccinationinformationinpersonaldecisionmaking.Thus,in ordertoincreasetheeffectivenessofhealthmessages,communi- catorsshouldstrivetomakethegistofthemessagememorable.

5. Openquestions

Vaccine narratives do not have to be negative. Emotionally powerfulstories couldbe toldabouta parents’ reliefat know- ingtheirchildrenareprotectedduringanoutbreak.Alternatively, narrativescouldshowthepainofsomeonewholostalovedone throughapreventabledisease.Whilenostudieshaveenumerated therepresentationofsuchinformationontheInternet,astudyof theAustralianprintmediafoundthatsuchnarrativeswereoften usedas moral talesabout theeffectsof non-vaccination [124].

However,welackstudiescomparingtheeffectofpro-andanti- vaccinationnarrativesonvaccinationintentions.Pro-vaccination messagesshouldbeanalyzedregardingtheireffectsonriskper- ceptionandvaccinationintention.Moreevidenceisneededonhow narrativescouldbeusedtoreportthepositiveeffectsofrecom- mendedvaccinations.Whatfactorsinfluencetheeffectivenessof narratives(e.g.messagevalence,sendercredibility,personalcon- tact)?Inlinewiththeposedquestions,arecentliteraturereview ontheeffectofnarrativesinmedicaldecisionaidsconcludesthat

“untilevidenceisprovidedonwhyandhownarrativesinfluence decisionmaking,theuseofnarrativesininterventionstofacilitate medicaldecisionmakingshouldbetreatedcautiously”[86].Thus, themannerinwhichriskcommunicationismosteffective(e.g.a certaincombinationofnarrativesandstatisticalevidence)willbe subjectoffutureresearch.

ThereisgoodreasontoassumethatWeb2.0canbefruitfully usedbypublichealthauthorities.However,researchisneededthat directlyinvestigatestheeffectivenessoftheWeb2.0activitiesof publichealth communicators.Thecentralquestionwillconcern howcomplexscientificinformationcanbecondensedintobrief andeffectivemessages.

ForsuccessfulInternetcommunicationactivities,itisnotonly necessarytothoughtfullycreatecontentbutalsopostthemessages onwebsitesthatarelikelytobeaccessedbytheintendedaudience.

Moreresearchisneededonhowusersfindtheirwaythroughthe Internetaswellasunderwhichconditionstheyusetheprovided informationratherthansimplycontinuingtheirsearch.

6. Recommendationsforpractice

The following recommendations for practice are “informed inferences” rather than evidence-based recommendations. We encourageresearcherstofurtherexpandtheevidencebase.Pub- lichealthcommunicatorsareneverthelessencouragedtouseand evaluatethesecommunicationguidelines.

Weassumethatsocialmediaisawidelyusedtoolthatpublic health communication can harness. In the social media envi- ronment,publichealth communicatorsshouldactivelystriveto establishanonline-reputationasexpertswhoareworthfollow- ingor assourcesonwebsites worthvisiting. Theopportunities heldbyrecentandadvancingtechnologicaldevelopmentsshould beusedfor interpersonalcommunication and interactivity(e.g.

Twitter,socialnetworks).Effectivecommunicationaboutvaccina- tionsmaynotbeabout“controllingwhatisavailablebutrather

it isabout respondingand participatingin aninteractive,user- responsiveenvironment”[8].Thus,inadditiontofastresponding, itisnecessarytoproactivelypreparecommunicationplansrather thansimplywaituntilnewscaresarrive[29].

Basedontheconsiderationsabove,communicationinthiscon- textmayprofitfromthefollowingprinciples:

Decide what the gist is and then communicate it clearly. The gistthat peopleextractfrominformation answers thequestion

“What doesthis information meanto me?” Even when people accuratelyrememberverbatimfactsfromahealthmessage,their judgmentsanddecisionsreflecthowtheyunderstandthegist.In ordertoincreasetheeffectivenessofhealthmessages,communi- catorsshouldthereforestrivetomakethegistmemorable.

Understand your audience’s needs and abilities and provide messages appropriate to your audience. To appropriately target information,communicatorsmustknowtheiraudience.Targeting shouldthereforeconsidernotonlytherecipients’priorknowledge butalsotheircapacitytoprocesstheinformation,suchasnumeracy andhealthliteracy,aswellastheirpreferencesforhowinformation ispresented[92].

7. Conclusion

Giventhatthebenefitsofvaccinationareintangiblewhilethe costsaretangible,theprobabilityofInternetuserstoshareneg- ative(vs.positive) vaccinationexperiencesvia Web2.0 toolsis potentiallyhigher.AsaresultoftheInternetandWeb2.0,private andpublicconcernsaboutvaccineshavethepotentialtovirally spreadacrosstheglobeinaquick,efficientandvividmanner.Web 2.0mayinfluencevaccinationdecisionsbydeliveringinformation thatalterstheperceivedpersonalriskofvaccine-preventabledis- easesorvaccinationside-effects.Itappearsusefulforpublichealth actorstoplaceeffortintoincreasingtheeffectivenessoftheexistent communicationbyusingtheopportunityofinteractive,customized communication;thismaybefacilitatedbyclearlyprovidingthegist oftheintendedmessage.Onekeytosuccessfulpublichealthcom- municationistoidentifythosewhoareparticularlyvulnerableto findingandusingunreliableandmisleadinginformation.Itseems worthwhilethatpublichealthwebsitesstrivetobeeasytofindby meansofsearchengineoptimization,especiallywhenlessknowl- edgeableindividualsareinneedofreliableinformationaboutthe risksandbenefitsofvaccination.

Acknowledgments

Allauthorscontributedtotheplanningandwritingofthisarti- cle. The sequence of authorsis alphabetical. Wethank Brian J.

Zikmund-Fisherwhoalsoattendedtheconferenceandprovided inputtoanearlierdraftofthiscontribution.

WegratefullyacknowledgethesponsorsoftheRisk2.0meeting:

UniversityofErfurt;EuropeanCentreforDiseasePreventionand Control(ECDC);GermanScienceFoundation(DFG;BE3970/5-1);

andFördervereinzurBekämpfungderViruskrankheitene.V.We thankthestudentsElisaHerbert,DorotheaHahn,PhilippSchmid, andNiklasHochgürtelfortheirsupportduringtheconference.

References

[1]Internetworldstats.com[Internet].Availableathttp://www.Internetworld stats.com/am/us.htm.

[2]Harris Interactive. The Harris Poll Shows Number of Cyberchondri- acs – Adults Who Have Ever Gone Online for Health Information – Increases to an Estimated 136 MillionNationwide; 2006. Available at:

http://www.harrisinteractive.com/vault/Harris-Interactive-Poll-Research- FOR-IMMEDIATE-RELEASE-2006-08.pdf(21.09.2011).

[3] FoxS.PewInternet&AmericanLifeProject:TheEngagedE-PatientPopu- lation;2008.Availableat:http://www.pewinternet.org/Reports/2008/The- Engaged-Epatient-Population.aspx.

[4]KummervoldPE,ChronakiCE,LausenB,ProkoschHU,RasmussenJ,Santana S,etal.eHealthtrendsinEurope2005–2007:apopulation-basedsurvey.

JournalofMedicalInternetResearch2008;10(4):e42.

[5]BeanSJ.Emergingandcontinuingtrendsinvaccineoppositionwebsitecon- tent.Vaccine2011;29(10):1874–80.

[6]O’Reilly T. What Is Web 2.0? Design Patterns and Business Mod- els for the Next Generation of Software; 2005. Available at:

http://oreilly.com/web2/archive/what-is-web-20.html.

[7]MusserJ,O’ReillyT.O’ReillyRadarReport:Web2.0PrinciplesandBestPrac- tices:O’ReillyMedia2006:7.

[8]WittemanHO,Zikmund-FisherBJ.ThedefiningcharacteristicsofWeb2.0 and their potential influence inthe onlinevaccinationdebate. Vaccine 2012;30:3734–40.

[9] Trepte S,Reinecke L. Unterhaltung online–Motive, Erleben, Effekte. In:

Schweiger W,BeckK,editors. HandbuchOnline-Kommunikation. Wies- baden:VS-Verlag;2010.p.211–33.

[10]SnyderLB,HamiltonMA.Ameta-analysisofU.S.healthcampaigneffects onbehavior:emphasizeenforcement,exposure,andnewinformation,and bewaretheseculartrend.In:HornikRC,editor.Publichealthcommunica- tion:Evidenceforbehaviorchange.Mahwah,NJ:LawrenceErlbaum;2002.

p.357–84.

[11]Derzon JH, Lipsey MW. A meta-analysis of the effectiveness of mass- communication for changing substance-use knowledge, attitudes, and behavior.In:CranoWD,BurgoonM,editors.Massmediaanddrugpreven- tion:Classicandcontemporarytheoriesandresearch.Mahwah,NJ:Erlbaum;

2002.p.231–58.

[12]NeuhauserL,KrepsGL.Rethinkingcommunicationinthee-healthera.Journal ofHealthPsychology2003;8(1):7–23.

[13]CassellMM,JacksonC,CheuvrontB.HealthcommunicationontheInternet:

aneffectivechannelforhealthbehaviorchange?JournalofHealthCommu- nication1998;1998(3):71–9.

[14] SouthwellBG,YzerMC.When(andwhy)interpersonaltalkmattersforcam- paigns.CommunicationTheory2009;19(1):1–8.

[15]Dutta-BergmanMJ.Healthcommunicationontheweb:therolesofweb usemotivationandinformationcompleteness.CommunicationMonographs 2003;70:264–74.

[16]DellaLJ,ErogluD,BernhardtJM,EdgertonE,NallJ.Lookingtothefutureof newmediainhealthmarketing:derivingpropositionsbasedontraditional theories.HealthMarketingQuarterly2008;25:147–74.

[17] Kasperson RE, Renn O, Slovic P, Brown HS, Emel J, Goble R, et al.

The socialamplificationof risk:aconceptual framework.Risk Analysis 1988;8(2):177–87.

[18]KaplanAM,HaenleinM.Twoheartsinthree-quartertime:howtowaltzthe socialmedia/viralmarketingdance.BusinessHorizons2001;54(3):253–63.

[19] AbromsLC,LefebvreRC.Obama’swiredcampaign:lessonsforpublichealth communication.JournalofHealthCommunication2009;14:415–23.

[20]ThackerayR,NeigerBL,HansonCL,McKenzieJF.Enhancingpromotional strategieswithinsocialmarketingprograms:useofWeb2.0socialmedia.

Healthpromotionpractice2008;9:338.

[21]KreuterMW,FarrellD,OlevitchL,BrennanL.Tailoredhealthmessages:Cus- tomizingcommunicationwithcomputertechnology.MahwahNJ:Lawrence Erlbaum;1999.

[22] NoarSM,BenacCN,HarrisMS.Doestailoringmatter?Meta-analyticreview oftailoredprinthealthbehaviorchangeinterventions.PsychologicalBulletin 2007;133(4):673–93.

[23]DaviesP,ChapmanS,LeaskJ.AntivaccinationactivistsontheWorldWide Web.ArchivesofDiseaseinChildhood2002;87(1):22–5.

[24]KataA.ApostmodernPandora’sbox:anti-vaccinationmisinformationonthe Internet.Vaccine2010;28(7):1709–16.

[25]KeelanJ,Pavri-GarciaV,TomlinsonG,WilsonK.YouTubeasasourceofinfor- mationonimmunization:acontentanalysis.JAMA2007;298(21):2482–4.

[26]Keelan J, PavriV,BalakrishnanR, Wilson K.Ananalysisofthe human papilloma virusvaccine debate onMySpaceblogs.Vaccine2010;28(6):

1535–40.

[27]SkeaZC,EntwistleVA,WattI,RussellE.‘Avoidingharmtoothers’considera- tionsinrelationtoparentalmeasles,mumpsandrubella(MMR)vaccination discussions–ananalysisofanonlinechatforum.SocialScience&Medicine 2008;67(9):1382–90.

[28]Betsch C, Renkewitz F, Betsch T,Ulshöfer C. Theinfluence of vaccine- criticalwebsitesonperceivingvaccinationrisks.JournalofHealthPsychology 2010;15(3):446–55.

[29]LeaskJ.Targetthefence-sitters.Nature2011;473:443–5.

[30]BetschC.Innovationsincommunication:theInternetandthepsychologyof vaccinationdecisions.Eurosurveillance2011;16(17),pii=19849.

[31]BundeszentralefürgesundheitlicheAufklärung.ElternbefragungzumThema ,ImpfenimKindesalterErgebnisberichtMai2011.

[32] BMRB.SocialResearchChildhoodimmunisation:Wave24report– England andminorityethnicrespondents.Unpublishedreport2004.

[33]HughesJH,CatesJR,LiddonN,SmithJS,GottliebSL,BrewerNT.Disparities inhowparentsarelearningaboutthehumanpapillomavirusvaccine.Cancer EpidemiologyBiomarkers&Prevention2009;18:363–72.

[34]ArmitageCJ,ConnerM.Socialcognitionmodelsandhealthbehavior:astruc- turedreview.PsychologyandHealth2000;15:173–89.

[35] RennerB,SchwarzerR.Social-cognitivefactorspredictinghealthbehavior change.In:SulsJ,WallstonK,editors.Socialpsychologicalfoundationsof healthandillness.Oxford:Blackwell;2003.p.169–96.

[36]AlkuwariMG,SelimNA,NazzalZAS,Al-NuaimiSA. Pandemicinfluenza A/H1N1vaccinationuptakeamonghealthcareworkersinQatar:motivators andbarriers.Vaccine2011;29:2206–11.

[37]Brewer NT, ChapmanGB, Gibbons FX, Gerrard M, McCaul KD, Wein- steinND.Meta-analysisoftherelationshipbetweenriskperceptionand healthbehavior:theexampleofvaccination.HealthPsychology2007;26(2):

136–45.

[38] GaygisizU,GaygisizE,OzkanT,LajunenT.WhywereTurksunwillingto accepttheA/H1N1influenza-pandemicvaccination?People’sbeliefsandper- ceptionsabouttheswinefluoutbreakandvaccineinthelaterstageofthe epidemic.Vaccine2010;29:329–33.

[39] LiaoQ, CowlingBJ,LamWWT,FieldingR.Factorsaffectingintentionto receiveandself-reportedreceiptof2009pandemic(H1N1)vaccineinHong Kong:alongitudinalstudy.PLoSONE2011;6(3):e17713,doi:10.1371/jour- nal.pone.0017713.

[40] RennerB,ReuterT.Thenumbersofriskaffect-relatedriskperceptionand vaccination:thecaseofthenewAH1N1influenza.Submittedforpublication.

[41] WeinsteinND.Perceivedprobabilityperceivedseverityandhealth-protective behavior.HealthPsychology2000;19:65–74.

[42] LoewensteinG,WeberE,HseeC,WelchN.Riskasfeelings.Psychological Bulletin2001;127:267–86.

[43]SlovicP,PetersE.Riskperceptionandaffect.CurrentDirectionsinPsycholog- icalScience2006;15(6):322–5.

[44]CacioppoJT,BerntsonGG.Relationshipbetweenattitudesandevaluative space:acriticalreview,withemphasisontheseparabilityofpositiveand negativesubstrates.PsychologicalBulletin1994;115:401–23.

[45]LangPJ,BradleyMM,CuthbertBN.Motivatedattention:affect,activation, andaction.In:LangPJ,SimonsRF,BalabanM,editors.Attentionandori- enting:Sensoryandmotivationalprocesses.Hillsdale,NJ:Erlbaum;1997.

p.97–135.

[46]BauchCT,EarnDJD.Vaccinationand thetheory ofgames.Proceedings of theNational Academy of Sciencesof the United States of America 2004;101:13391–4.

[47]Institue of Medicine of the National Academics. Adverse Effects of Vaccines: Evidence and Causality. Available at http://www.iom.edu/

Reports/2011/Adverse-Effects-of-Vaccines-Evidence-and-Causality.aspx.

[48]SchneeweißB, PfleidererM,Keller-StanislawskiB. Impfsicherheitheute.

DeutschesÄrzteblatt2008;105:590–5.

[49]LeaskJ,ChapmanS,RobbinsSCC.Allmannerofills:thefeaturesofserious diseasesattributedtovaccination.Vaccine2010;28:3066–70.

[50]BlackS,EskolaJ,SiegristCA,etal.Importanceofbackgroundratesofdisease inassessmentofvaccinesafetyduringmassimmunisationwithpandemic H1N1influenzavaccines.Lancet2009;374:2115–22.

[51] FoxS.,RainieL.Vitaldecisions.[Internet]Availableathttp://wwwpewinter- netorg/.

[52]FoxS.(2006).PewInternet&AmericanLifeProject:http://www.pewinternet.

org/Reports/2006/Online-Health-Search-2006.aspx.

[53] SurowieckiJ.Thewisdomofcrowdswhythemanyaresmarterthanthefew.

NewYork:DoubledayBooks;2004.

[54]GilesJ.Internetencyclopaediasgoheadtohead.Nature2005;438:900–1.

[55]KataA.Anti-vaccineactivists,Web2.0,andthepostmodernparadigm–an overviewoftacticsandtropesusedonlinebytheanti-vaccinationmovement.

Vaccine2012;30:3778–89.

[56]RobertKoch-Institute.Paul-Ehrlich-Institute.Vaccination–20objectionsand responses.2007.Availablefrom:http://www.rki.de/cln169/nn216436/EN/

Content/Prevention/Vaccination/Vaccination download,templateId=raw, property=publicationFile.pdf/Vaccinationdownload.pdf.

[57]Scullard P, Peacock C, Davies P. Googling children’s health: reliability of medical advice on the internet. Archives of Disease in Childhood 2010;95(8):580–2.

[58]BetschC,WickerS.HowGermanmedicalstudentsperceiveinfluenzaand vaccinationrisksinrelationtoknowledgeaboutvaccinationandpersonal e-healthuse.Vaccine2012,http://dx.doi.org/10.1016/j.vaccine.2011.12.021.

[59] CottonSR,GuptaSS.Characteristicsofonlineandofflinehealthinforma- tionseekersandfactorsthatdiscriminatebetweenthem.SocialScience&

Medicine2004;59:1795–806.

[60]ZillienN,HargittaiE.Digitaldistinction:status-specific.InternetUsesSocial ScienceQuarterly2009;90(2):274–91.

[61]FreeseJ,RivasS,HargittaiE.Cognitiveabilityandinternetuseamongolder adultspoetics.JournalofEmpiricalResearchonCulturetheMediaandthe Arts2006;34(4):236–49.

[62]ZarcadoolasC, Pleasant A, Greer D. Understanding health literacy: an expandedmodel.HealthPromotionInternational2005;20:195–203.

[63]HargittaiE.Surveymeasuresofweb-oriente.DigitalLiteracySocialScience ComputerReview2005;23(3):371–9.

[64]HargittaiE.Anupdateonsurveymeasuresofweb-oriente.DigitalLiteracy SocialScienceComputerReview2009;27(1):130–7.

[65]DownsJS,deBruinWB,FischhoffB.Parents’vaccinationcomprehensionand decisions.Vaccine2008;26(12):1595–607.

[66]ReynaVF,NelsonWL,HanPK,DieckmannNF.Hownumeracyinfluences riskcomprehensionandmedical decisionmaking.PsychologicalBulletin 2009;135:943–73.

[67]BoothA.Abeautifularm;ahistoryofthevaccinationdelusion.London:Low, Marston;1909.

[68] SpierRE.Perceptionofriskofvaccineadverseevents:ahistoricalperspective.

Vaccine2002;20(Suppl):78–84.