JPediatr(RioJ).2016;92(4):328---330
www.jped.com.br
EDITORIAL
Varicella
complications
and
universal
immunization
夽
,
夽夽
Complicac
¸ões
e
imunizac
¸ão
universal
contra
a
varicela
Elena
Bozzola
a,∗,
Mauro
Bozzola
baDepartmentofPediatrics,PediatricandInfectiousDiseasesUnit,BambinoGesùChildren’sHospital,Rome,Italy bInternalMedicineandTherapeuticsDepartment,PediatricsandAdolescentologyUnit,UniversityofPavia,
FondazioneIRCCSSanMatteo,Pavia,Italy
Varicellaisoneofthemostcommoninfectiousdiseases,with aworldwidedistribution.AccordingtoaWHOpositionpaper, theglobalannualdiseaseburdenofvaricellaisestimatedto be140millioncases.1Despitethepublicperceptionof
vari-cellainfectionasaharmlesschildhoodaffliction,itcanbe
a veryserious disease. As MartinoMota & Carvalho-Costa
highlightin‘‘Varicellazostervirusrelateddeathsand
hos-pitalizationsin Brazil beforethe introductionof universal
vaccinationwiththetetraviralvaccine,’’varicellacancause
deathorcanleadtopotentiallyseriouscomplications,which
requirehospitalizationandeventuallylong-termsequelae.2
Varicella-related hospitalization rates differ widely
worldwide. Varicella may potentially afflict any organ;
hematological, neurological, respiratory, cutaneous,
hepatic,gastrointestinal, urinary, and bone complications
arethemostfrequentlyreported.3
The incidence ofvaricella complications differs among
scientific reports. For example, the pooled prevalence
of neurological complications resulting from a systematic
reviewoftheliteratureidentifiesthelikelihoodofpediatric
neurologicalcomplicationsintherangeof13.9---20.4%.4
Nev-ertheless,insomereportstherateofvaricellaneurological
夽
Please cite this article as: Bozzola E, Bozzola M. Varicella complications and universal immunization. J Pediatr (Rio J). 2016;92:328---30.
夽夽
SeepaperbyMartinoMota&Carvalho-Costainpages361---6.
∗Correspondingauthor.
E-mail:[email protected](E.Bozzola).
complications is lowerthanthe incidencereportedin the
literature, while other complications, such as skin
infec-tions,arethemostfrequentlydetected.5,6Inotherreports,
therateofbothneurologicalandcutaneouscomplications
islow,whileother complicationsarefrequentlydetected,
such as respiratory ones.7 This finding may berelated to
differencesinthesociodemographicstructureofthe
popula-tionortoabroaderavailabilityofoutpatientskin-infection
treatmentsortodifferenthospitalizationpolicies.
Patientswithahistoryofunderlyingmalignancy,steroid
use or immunosuppressive therapy,HIV infection, or solid
organtransplantationaresusceptibletodisseminated
vari-celladuetoimpairedcellularimmunity.Immunosuppressed
hostswhodevelopvaricellaexperienceseveremorbidityand
highermortalityrates morefrequentlythannormalhosts.
Forexample,patientswithrheumatologicor
gastroentero-logical diseases treated with tumor necrosis factor (TNF)
antagonists remain at selectively increased risk for more
severeprimaryvaricellainfectionscomparedwiththe
gen-eralpopulation.8,9
In the report by Martino Mota & Carvalho-Costa, the
majorityofdeathsandofvaricella-associatedcomplications
occurredinchildrenaged1---4years.Similarly,inthe
litera-ture,thehighestfrequencyofvaricellacomplicationsoccurs
inthoseyoungerthan5years.3,6,10
Varicellamay also be veryserious in the elderly, as it
maybefatalorleadtoprolongedhospitalization.8Pregnant
womenareaparticularconcern.Ifawomandevelops
vari-cellaatanearlygestationalage,thechildmayexperience
congenitalvaricellasyndrome;ifshegetsillat theendof
http://dx.doi.org/10.1016/j.jped.2016.05.001
Varicellacomplicationsanduniversalimmunization 329
pregnancy,theneonatemaypresentvaricella.Both
condi-tionsareveryseriousforthenewborn.11
Vaccination may prevent varicella infection and its
complications.Avaricellavaccine,basedontheattenuated
livevaricellazostervirusOkastrain,wasdevelopedinJapan
inthemid-1970s.Sincethen,differentformulationsof
vari-cellavaccineshadbeenproposed.Allofthemcontainlive
attenuatedvaricellazostervirus,andall,exceptthevaccine
licensed in South Korea,are basedon theOka strain
iso-latedinJapan.Currently,varicellavaccinesarelicensedas
amonovalentorasacombinationmeasles,mumps,rubella,
varicellavaccine(MMRV).MMRVvaccinesarecurrentlyused
onthe basis of a comparableimmunogenicity andoverall
safety profile compared withsimultaneous administration
of MMR and varicella vaccines.12 Moreover, as it requires
asingleinjection,MMRVvaccine is expectedtooffer
sev-eralbenefits:facilitationofuniversalimmunizationagainst
thesefourdiseases,increasedcompliancewith
immuniza-tion,andreducedhealthcarecosts.
In a study focusing on post-licensure varicella vaccine
effectiveness among healthy children, the authors
ana-lyzedsystematicreviewsandmeta-analysesoftheMEDLINE,
Embase,CochraneLibrary,andCINAHLdatabasesforreports
publishedduring1995---2014.Theyconcludedthatonedose
ofvaricellavaccinewasmoderatelyeffectiveinpreventing
varicelladiseases (81%)andhighly effectivein preventing
moderateandseveremanifestationsofvaricella(98%).The
authorsconcludedthatasecond doseadds increased
pro-tectionagainstvaricella(92%).13
Nevertheless, vaccination policies differ from country
to country. In some, such as the United States and
Aus-tralia, universal immunizationwasintroduced many years
ago.Suchmassvaccinationprogressivelyledtoasubstantial
decreaseindiseaseburden.14
With regard toEurope, there is noconsensus on
vari-cella immunization policy. Consequently, some countries,
such as Germany and Greece, have national childhood
immunizationprograms.Othersadoptheterogeneousorno
officialrecommendations.15 InItaly, sinceits
commercial-ization,someregionshaveoffereduniversalvaccinationin
childhood, witha consequently reduced incidence of the
disease.16
In other regions, varicella vaccine coverage strongly
dependson theacceptance of thevaccination byparents
andonpediatricians’recommendations.Pediatricians may
underestimateboththepotentialriskofthediseaseandthe
economicburdenforthecommunity.Parentsmayconsider
the potential profit for the community as less important
thantheindividualrisktotheirchildfrompotential
uninten-tionalsideeffectsofvaccination.Vaccine-decliningparents
believethatthevaccine isunsafeandineffective, aswell
as that the disease it is given to prevent is mild and
harmless.Moreover,insomecases,parentsmistrusthealth
professionals,thegovernment,andofficially-endorsed
vac-cineresearchbuttrustmediaandnon-officialinformation
sources, which discourage immunization policies. In most
cases,familiesmustpaythecostofvaccinationiftheywish
theirchildrentobeimmunized.Hence,highcoveragelevels
maybedifficulttoachieve.
Decisionsonvaccinefundingarebasedonmany
consid-erations,includingthelikelycost-effectivenessofdifferent
immunization strategies. In European countries that have
implementedvaccinationonanational level,mass
immu-nizationhas resulted in both decreased diseaseincidence
andreducedhospitalizationrates.Moreover,datahavealso
revealedbenefitsfor unvaccinatedgroups,suchasinfants
youngerthanoneyear.17 Infact,ahighimmunizationrate
contributesinpreventingthespreadofvaricellainfection,
aconceptknownasherdimmunity.Herdimmunityprovides
protectiontothosewhoareathighestriskforsevere
vari-cellainfection,includingpregnantwomen,infants,persons
with human immunodeficiency virus and other
immuno-deficiency disorders, those receiving chemotherapy, and
patients treated with high-dose corticosteroids. This is a
veryimportantgoal,asmanyhospitaladmissions occurin
infants too young to be vaccinated.3 Therefore, as rates
ofvaccinerefusalincrease,herdimmunitywanes,and
cer-tainvulnerablepopulationswillbeathigherriskforsevere
varicellainfection.
Further,aneconomicanalysisofauniversalvaccination
programindicatesthatitwouldlikelybecost-savingdueto
reductioninbothmedicalcostsandinlossofparents’work
time.18 Finally, countries shouldalso considervaccination
ofseronegativehealth-careworkers,especiallyinsettings
wheretheriskofseverevaricellaishigh(i.e.,
immunocom-promisedpatients,prematureinfants,etc.).
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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