biostudies-literatureUnknown74(7)Skowronski DMRoche, Hologic, and SiemensPublic Health Agency of CanadaGlaxoSmithKlineSymvivoPfizerBC Children’s Hospital FoundationMichael Smith Foundation for Health ResearchSanofi-PasteurSeqirusCanadian Institutes of Health ResearchMerckCanadian Child Health Clinician Scientist Program,<h4>Background</h4>Randomized-controlled trials of messenger RNA (mRNA) vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) included relatively few elderly participants. We assess single-dose mRNA vaccine effectiveness (VE) in adults ≥ 70 years old in British Columbia, Canada, where second doses were deferred by up to 16 weeks and where a spring 2021 wave uniquely included codominant circulation of Alpha (B.1.1.7) and Gamma (P.1) variants of concern (VOC).<h4>Methods</h4>Analyses included community-dwelling adults ≥ 70 years old with specimen collection between 4 April (epidemiological week 14) and 1 May (week 17) 2021. Adjusted VE was estimated by test-negative design. Cases were reverse-transcription polymerase chain reaction (RT-PCR) test-positive forClinical infectious diseases : an official publication of the Infectious Diseases Society of America1158-1165https://www.ebi.ac.uk/biostudies/studies/S-EPMC8406884biostudies-literatureSingle-dose mRNA Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Including Alpha and Gamma Variants: A Test-negative Design in Adults 70 Years and Older in British Columbia, Canada.PMC8406884Zou MPatrick DMHenry BEl Adam SSkowronski DMJassem ANKrajden MSadarangani MHoang LMNPrystajecky NSetayeshgar SNaus MTyson JRSbihi HGalanis EfalseSingle-dose mRNA Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Including Alpha and Gamma Variants: A Test-negative Design in Adults 70 Years and Older in British Columbia, Canada.<h4>Background</h4>Randomized-controlled trials of messenger RNA (mRNA) vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) included relatively few elderly participants. We assess single-dose mRNA vaccine effectiveness (VE) in adults ≥ 70 years old in British Columbia, Canada, where second doses were deferred by up to 16 weeks and where a spring 2021 wave uniquely included codominant circulation of Alpha (B.1.1.7) and Gamma (P.1) variants of concern (VOC).<h4>Methods</h4>Analyses included community-dwelling adults ≥ 70 years old with specimen collection between 4 April (epidemiological week 14) and 1 May (week 17) 2021. Adjusted VE was estimated by test-negative design. Cases were reverse-transcription polymerase chain reaction (RT-PCR) test-positive for2022-01-01T00:00:00Z2022 Apr2026-05-08T22:53:27.552Z2022-02-11T09:58:26.215ZS-EPMC84068843424472310.1093/cid/ciab616