Severity of omicron variant of concern and effectiveness of vaccine boosters against symptomatic disease in Scotland (EAVE II): a national cohort study with nested test-negative design

Aziz Sheikh* (Corresponding Author), Steven Kerr, Mark Woolhouse, Jim McMenamin, Chris Robertson, EAVE II Collaborators, Colin Richard Simpson, Tristan Millington, Ting Shi, Utkarsh Agrawal, Safraj Shahul Hameed, Elliott Hall, Igor Rudan, Syed Ahmar Shah, Lewis Ritchie, Sarah Stock, Colin McCowan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)
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Abstract

Summary Background Since its emergence in November, 2021, in southern Africa, the SARS-CoV-2 omicron variant of concern (VOC) has rapidly spread across the world. We aimed to investigate the severity of omicron and the extent to which booster vaccines are effective in preventing symptomatic infection. Methods In this study, using the Scotland-wide Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 (EAVE II) platform, we did a cohort analysis with a nested test-negative design incident case-control study covering the period Nov 1–Dec 19, 2021, to provide initial estimates of omicron severity and the effectiveness of vaccine boosters against symptomatic disease relative to 25 weeks or more after the second vaccine dose. Primary care data derived from 940 general practices across Scotland were linked to laboratory data and hospital admission data. We compared outcomes between infection with the delta VOC (defined as S-gene positive) and the omicron VOC (defined as S-gene negative). We assessed effectiveness against symptomatic SARS-CoV-2 infection, with infection confirmed through a positive RT-PCR. Findings By Dec 19, 2021, there were 23 840 S-gene-negative cases in Scotland, which were predominantly among those aged 20–39 years (11 732 [49·2%]). The proportion of S-gene-negative cases that were possible reinfections was more than ten times that of S-gene-positive cases (7·6% vs 0·7%; p
Original languageEnglish
Pages (from-to)959-966
Number of pages8
JournalThe Lancet Infectious Diseases
Volume22
Issue number7
Early online date22 Jun 2022
DOIs
Publication statusPublished - Jul 2022

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