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dc.contributor.authorNordström, Peter
dc.contributor.authorBallin, Marcel
dc.contributor.authorNordström, Anna Hava
dc.date.accessioned2023-01-06T09:58:17Z
dc.date.available2023-01-06T09:58:17Z
dc.date.issued2022-10-03
dc.description.abstractBackground - The effect of a fourth dose of COVID-19 vaccine on the risk of death in the oldest and frailest individuals is unknown.<p> <p>Methods - Two matched cohorts were formed using Swedish nationwide registers. In the first, residents of long-term care facilities (LTCFs) given a fourth dose of an mRNA vaccine from 1 January 2022 onwards were matched 1:1 on birth year and county of residence to residents given at least a third dose (N = 24,524). In the second, all individuals aged ≥80 years given a fourth dose were matched 1:1 to individuals given at least a third dose (N = 394,104). Cox regression models were used to estimate hazard ratios for all-cause mortality in fourth-dose recipients as compared with in third-dose recipients, with relative vaccine effectiveness (VE) estimated as 1 minus the hazard ratio.<p> <p>Findings - From 7 days after baseline and onwards, there were 1119 deaths in the LTCF cohort during a median follow-up of 77 days and a maximum follow-up of 126 days. During days 7 to 60, the VE of the fourth dose was 39% (95% CI, 29-48), which declined to 27% (95% CI, -2-48) during days 61 to 126. In the cohort of all individuals aged ≥80 years, there were 5753 deaths during a median follow-up of 73 days and a maximum follow-up of 143 days. During days 7 to 60, the VE of the fourth dose was 71% (95% CI, 69-72), which declined to 54% (95% CI, 48-60) during days 61 to 143. The VE of the fourth dose seemed stronger when it was compared to third-dose recipients where at least four months had passed since vaccination (P < 0·001 for interaction).<p> <p>Interpretation - As compared with a third dose, a fourth dose of an mRNA COVID-19 vaccine, administered during the Omicron era, was associated with reduced risk of death from all causes in residents of LTCFs and in the oldest old during the first two months, after which the protection became slightly lower. These findings suggest that a fourth dose may prevent premature mortality in the oldest and frailest even after the emergence of the Omicron variant, although the timing of vaccination seems to be important with respect to the slight waning observed after two months.en_US
dc.identifier.citationNordström P, Ballin M, Nordström AH. Effectiveness of a fourth dose of mRNA COVID-19 vaccine against all-cause mortality in long-term care facility residents and in the oldest old: A nationwide, retrospective cohort study in Sweden.. The Lancet Regional Health - Europe. 2022en_US
dc.identifier.cristinIDFRIDAID 2100985
dc.identifier.doi10.1016/j.lanepe.2022.100466
dc.identifier.issn2666-7762
dc.identifier.urihttps://hdl.handle.net/10037/28045
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.relation.journalThe Lancet Regional Health - Europe
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2022 The Author(s)en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0en_US
dc.rightsAttribution 4.0 International (CC BY 4.0)en_US
dc.titleEffectiveness of a fourth dose of mRNA COVID-19 vaccine against all-cause mortality in long-term care facility residents and in the oldest old: A nationwide, retrospective cohort study in Sweden.en_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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Attribution 4.0 International (CC BY 4.0)
Med mindre det står noe annet, er denne innførselens lisens beskrevet som Attribution 4.0 International (CC BY 4.0)