High effectiveness of mix-and-match COVID-19 vaccines

High effectiveness of mix-and-match COVID-19 vaccines. NEWS People who had received a first dose of the Oxford-AstraZeneca COVID-19 vaccine ... Published:18Oct,2021 Higheffectivenessofmix-and-matchCOVID-19vaccines NEWS PeoplewhohadreceivedafirstdoseoftheOxford-AstraZenecaCOVID-19vaccineandreceivedanmRNAvaccinefortheirseconddosehadalowerriskofinfectioncomparedtopeoplewhohadreceivedbothdosesoftheOxford-AstraZenecavaccine.ThisisshowninanationwidestudyperformedbyresearchersatUmeåUniversity. Text:OlaNilsson “Havingreceivedanyoftheapprovedvaccinesisbettercomparedtonovaccine,andtwodosesarebetterthanone,”saysPeterNordström,professorofgeriatricmedicineatUmeåUniversity.“However,ourstudyshowsagreaterriskreductionforpeoplewhoreceivedanmRNAvaccineafterhavingreceivedafirstdoseofavector-based,ascomparedtopeoplehavingreceivedthevector-basedvaccineforbothdoses.” SincetheuseofOxford-AstraZeneca’svector-basedvaccineagainstCOVID-19washaltedforpeopleyoungerthan65yearsofage,allindividualswhohadalreadyreceivedtheirfirstdoseofthisvaccinewererecommendedanmRNAvaccineastheirseconddose. Duringa2.5-monthaveragefollow-upperiodaftertheseconddose,thestudyshoweda67%lowerriskofinfectionforthecombinationofOxford-AstraZeneca+Pfizer-BioNTech,anda79%lowerriskforOxford/AstraZeneca+Moderna,bothcomparedtounvaccinatedindividuals.ForpeoplehavingreceivedtwodosesoftheOxford-AstraZenecavaccine,theriskreductionwas50%.Theseriskestimateswereobservedafteraccountingfordifferencesregardingdateofvaccination,ageoftheparticipants,socioeconomicstatus,andotherriskfactorsforCOVID-19.Importantly,theestimatesofeffectivenessapplytoinfectionwiththeDeltavariant,whichwasdominatingtheconfirmedcasesduringthefollow-upperiod.Therewasaverylowincidenceofadversethromboemboliceventsforallvaccineschedules.ThenumberofCOVID-19casessevereenoughtoresultininpatienthospitalizationwastoolowfortheresearcherstobeabletocalculatetheeffectivenessagainstthisoutcome.  Previousresearchhasdemonstratedthatmix-and-matchvaccineschedulesgeneratearobustimmuneresponse.However,ithasbeenuncleartowhichextenttheseschedulesmayreducetheriskofclinicalinfection.ThisistheknowledgegapwhichthenewstudyconductedbytheUmeåresearchersaimedtofill. ThestudyisbasedonnationwideregistrydatafromthePublicHealthAgencyofSweden,theNationalBoardofHealthandWelfare,andStatisticsSweden.Inthemainanalysis,about700,000individualswereincluded. “Theresultsofthestudymayhaveimplicationsforvaccinationstrategiesindifferentcountries,”saysMarcelBallin,doctoralstudentingeriatricmedicineatUmeåUniversityandco-authorofthestudy. “TheWorldHealthOrganizationhasstatedthatdespitethepromisingresultsfrompreviousstudiesregardingimmuneresponsefrommix-and-matchvaccination,thereisaneedforlargerstudiestoinvestigatetheirsafetyandeffectivenessagainstclinicaloutcomes.Herewenowhaveonesuchstudy.” ThestudyispublishedinthescientificjournalTheLancetRegionalHealth–Europe. Aboutthepublication EffectivenessofheterologousChAdOx1nCoV-19andmRNAprime-boostvaccinationagainstsymptomaticCovid-19infectioninSweden:AnationwidecohortstudyPeterNordström,MarcelBallin,AnnaNordström.DOI:10.1016/j.lanepe.2021.100249 Contact PeterNordström Professor,seniorconsultant(attending)physician E-mail Email Phone +46907858753 MarcelBallin Doctoralstudent E-mail Email