1. COVID-19 in non-hospitalised adults caused by either SARS-CoV-2 sub-variants Omicron BA.1, BA.2, BA.5 or Delta associates with similar illness duration, symptom severity and viral kinetics, irrespective of vaccination history
- Author
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Hermaleigh Townsley, Joshua Gahir, Timothy W Russell, Edward J Carr, Matala Dyke, Lorin Adams, Murad Miah, Bobbi Clayton, Callie Smith, Mauro Miranda, Harriet V Mears, Chris Bailey, James RM Black, Ashley S Fowler, Margaret Crawford, Katalin Wilkinson, Matthew Hutchinson, Ruth Harvey, Nicola O’Reilly, Gavin Kelly, Robert Goldstone, Rupert Beale, Padmasayee Papineni, Tumena Corrah, Richard Gilson, Simon Caidan, Jerome Nicod, Steve Gamblin, George Kassiotis, Vincenzo Libri, Bryan Williams, Sonia Gandhi, Adam J Kucharski, Charles Swanton, David LV Bauer, and Emma C Wall
- Abstract
BackgroundSARS-CoV-2 variant Omicron rapidly evolved over 2022, causing three waves of infection due to sub-variants BA.1, BA.2 and BA.4/5. We sought to characterise symptoms and viral loads over the course of COVID-19 infection with these sub-variants in otherwise-healthy, vaccinated, non-hospitalised adults, and compared data to infections with the preceding Delta variant of concern (VOC).MethodsIn a prospective, observational cohort study, healthy vaccinated UK adults who reported a positive PCR or lateral flow test, self-swabbed on alternate days until day 10. We compared symptoms and viral load trajectories between infections caused by VOCs Delta and Omicron (sub-variants BA.1, BA.2 and BA.4/5), and tested for relationships between vaccine dose, symptoms and PCR Ct value as a proxy for viral load.Results555 infection episodes were reported among 483 participants. Across VOCs, symptom burden and duration were similar, however symptom profiles differed among infections caused by Delta compared to Omicron sub-variants; symptoms of all Omicron sub-variants BA.1, BA.2 and BA.4/5 were very similar. Anosmia was reported in 7-13% of participants with Omicron sub-variants, compared to 25/60 (42%) with Delta infection (P= 1.31e-08 or 1.03e-05 or 5.63e-05; χ2test d2+Delta vs. Omicron BA.1 or vs. BA.2, or BA.5, respectively), fever was more common with Omicron BA.5 (30/55, 55%) than Delta (20/60, 33%) (p 0.03). Amongst infections with all Omicron sub-variants, symptoms of coryza, fatigue, cough and myalgia predominated. Viral load trajectories and peaks did not differ between Delta, and Omicron, irrespective of symptom severity (including asymptomatic participants), VOC or vaccination status. Ct values were negatively associated with time since vaccination in participants infected with BA.1; however, this trend was not observed in BA.2/BA.4/5 infections.ConclusionOur study emphasises both the changing symptom profile of COVID-19 infections in the Omicron era, and ongoing transmission risk of Omicron sub-variants in vaccinated adults.Trial registrationNCT04750356
- Published
- 2022