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Abstract

Several SARS-CoV-2 variants that evolved during the COVID-19 pandemic have appeared to differ in severity, based on analyses of single-country datasets. With decreased testing and sequencing, international collaborative studies will become increasingly important for timely assessment of the severity of new variants. Therefore, a joint WHO Regional Office for Europe and ECDC working group was formed to produce and pilot a standardised study protocol to estimate relative case-severity of SARS-CoV-2 variants during periods when two variants were co-circulating. The study protocol and its associated statistical analysis code was applied by investigators in Denmark, England, Luxembourg, Norway, Portugal and Scotland to assess the severity of cases with the Omicron BA.1 virus variant relative to Delta. After pooling estimates using meta-analysis methods (random effects estimates), the risk of hospital admission (adjusted hazard ratio (aHR) = 0.41; 95% confidence interval (CI): 0.31−0.54), admission to intensive care unit (aHR = 0.12; 95% CI: 0.05−0.27) and death (aHR = 0.31; 95% CI: 0.28−0.35) was lower for Omicron BA.1 compared with Delta cases. The aHRs varied by age group and vaccination status. In conclusion, this study demonstrates the feasibility of conducting variant severity analyses in a multinational collaborative framework and adds evidence for the reduced severity of the Omicron BA.1 variant.

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/content/10.2807/1560-7917.ES.2023.28.36.2300048
2023-09-07
2024-12-26
/content/10.2807/1560-7917.ES.2023.28.36.2300048
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References

  1. Bager P, Wohlfahrt J, Bhatt S, Stegger M, Legarth R, Møller CH, et al. , Omicron-Delta study group. Risk of hospitalisation associated with infection with SARS-CoV-2 omicron variant versus delta variant in Denmark: an observational cohort study. Lancet Infect Dis. 2022;22(7):967-76.  https://doi.org/10.1016/S1473-3099(22)00154-2  PMID: 35468331 
  2. Lewnard JA, Hong VX, Patel MM, Kahn R, Lipsitch M, Tartof SY. Clinical outcomes associated with SARS-CoV-2 Omicron (B.1.1.529) variant and BA.1/BA.1.1 or BA.2 subvariant infection in Southern California. Nat Med. 2022;28(9):1933-43.  https://doi.org/10.1038/s41591-022-01887-z  PMID: 35675841 
  3. Nyberg T, Ferguson NM, Nash SG, Webster HH, Flaxman S, Andrews N, et al. . Comparative analysis of the risks of hospitalisation and death associated with SARS-CoV-2 omicron (B.1.1.529) and delta (B.1.617.2) variants in England: a cohort study. Lancet. 2022;399(10332):1303-12.  https://doi.org/10.1016/S0140-6736(22)00462-7  PMID: 35305296 
  4. Peralta-Santos A, Rodrigues EF, Moreno J, Ricoca V, Casaca P, Fernandes E, et al. Omicron (BA.1) SARS-CoV-2 variant is associated with reduced risk of hospitalization and length of stay compared with Delta (B.1.617.2). medRxiv. 2022:2022.01.20.22269406.
  5. Sheikh A, Kerr S, Woolhouse M, McMenamin J, Robertson C, Simpson CR, et al. . 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. Lancet Infect Dis. 2022;22(7):959-66.  https://doi.org/10.1016/S1473-3099(22)00141-4  PMID: 35468332 
  6. Ulloa AC, Buchan SA, Daneman N, Brown KA. Estimates of SARS-CoV-2 Omicron Variant Severity in Ontario, Canada. JAMA. 2022;327(13):1286-8.  https://doi.org/10.1001/jama.2022.2274  PMID: 35175280 
  7. Veneti L, Bøås H, Bråthen Kristoffersen A, Stålcrantz J, Bragstad K, Hungnes O, et al. Reduced risk of hospitalisation among reported COVID-19 cases infected with the SARS-CoV-2 Omicron BA.1 variant compared with the Delta variant, Norway, December 2021 to January 2022. Euro Surveill. 2022;27(4):2200077.  https://doi.org/10.2807/1560-7917.ES.2022.27.4.2200077  PMID: 35086614 
  8. Ward IL, Bermingham C, Ayoubkhani D, Gethings OJ, Pouwels KB, Yates T, et al. Risk of covid-19 related deaths for SARS-CoV-2 omicron (B.1.1.529) compared with delta (B.1.617.2): retrospective cohort study. BMJ. 2022;378:e070695.  https://doi.org/10.1136/bmj-2022-070695  PMID: 35918098 
  9. Wolter N, Jassat W, Walaza S, Welch R, Moultrie H, Groome M, et al. Early assessment of the clinical severity of the SARS-CoV-2 omicron variant in South Africa: a data linkage study. Lancet. 2022;399(10323):437-46.  https://doi.org/10.1016/S0140-6736(22)00017-4  PMID: 35065011 
  10. Bager P, Wohlfahrt J, Rasmussen M, Albertsen M, Krause TG. Hospitalisation associated with SARS-CoV-2 delta variant in Denmark. Lancet Infect Dis. 2021;21(10):1351.  https://doi.org/10.1016/S1473-3099(21)00580-6  PMID: 34487704 
  11. Rodrigues EF, Moreno J, Leite PP, Casaca P, Nunes B, Gomes JP, et al. B.1.617.2 SARS-CoV-2 (Delta) variant is associated with increased risk of hospitalization and death compared with B.1.1.7 SARS-CoV-2 (Alpha) variant. medRxiv. 2022:2022.01.21.22268602 . https://doi.org/10.1101/2022.01.21.22268602 
  12. Sheikh A, McMenamin J, Taylor B, Robertson C, Public Health Scotland and the EAVE II Collaborators. SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet. 2021;397(10293):2461-2.  https://doi.org/10.1016/S0140-6736(21)01358-1  PMID: 34139198 
  13. Twohig KA, Nyberg T, Zaidi A, Thelwall S, Sinnathamby MA, Aliabadi S, et al. Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study. Lancet Infect Dis. 2022;22(1):35-42.  https://doi.org/10.1016/S1473-3099(21)00475-8  PMID: 34461056 
  14. Veneti L, Valcarcel Salamanca B, Seppälä E, Starrfelt J, Storm ML, Bragstad K, et al. No difference in risk of hospitalization between reported cases of the SARS-CoV-2 Delta variant and Alpha variant in Norway. Int J Infect Dis. 2022;115:178-84.  https://doi.org/10.1016/j.ijid.2021.12.321  PMID: 34902584 
  15. Bager P, Wohlfahrt J, Fonager J, Rasmussen M, Albertsen M, Michaelsen TY, et al. Risk of hospitalisation associated with infection with SARS-CoV-2 lineage B.1.1.7 in Denmark: an observational cohort study. Lancet Infect Dis. 2021;21(11):1507-17.  https://doi.org/10.1016/S1473-3099(21)00290-5  PMID: 34171231 
  16. Funk T, Pharris A, Spiteri G, Bundle N, Melidou A, Carr M, et al. , COVID study groups. Characteristics of SARS-CoV-2 variants of concern B.1.1.7, B.1.351 or P.1: data from seven EU/EEA countries, weeks 38/2020 to 10/2021. Euro Surveill. 2021;26(16):2100348.  https://doi.org/10.2807/1560-7917.ES.2021.26.16.2100348  PMID: 33890566 
  17. Nyberg T, Twohig KA, Harris RJ, Seaman SR, Flannagan J, Allen H, et al. Risk of hospital admission for patients with SARS-CoV-2 variant B.1.1.7: cohort analysis. BMJ. 2021;373(1412):n1412.  https://doi.org/10.1136/bmj.n1412  PMID: 34130987 
  18. Veneti L, Seppälä E, Larsdatter Storm M, Valcarcel Salamanca B, Alnes Buanes E, Aasand N, et al. Increased risk of hospitalisation and intensive care admission associated with reported cases of SARS-CoV-2 variants B.1.1.7 and B.1.351 in Norway, December 2020 -May 2021. PLoS One. 2021;16(10):e0258513.  https://doi.org/10.1371/journal.pone.0258513  PMID: 34634066 
  19. Menni C, Valdes AM, Polidori L, Antonelli M, Penamakuri S, Nogal A, et al. Symptom prevalence, duration, and risk of hospital admission in individuals infected with SARS-CoV-2 during periods of omicron and delta variant dominance: a prospective observational study from the ZOE COVID Study. Lancet. 2022;399(10335):1618-24.  https://doi.org/10.1016/S0140-6736(22)00327-0  PMID: 35397851 
  20. Vihta KD, Pouwels KB, Peto TEA, Pritchard E, House T, Studley R, et al. Omicron-Associated Changes in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Symptoms in the United Kingdom. Clin Infect Dis. 2023.  https://doi.org/10.1093/cid/ciab945 
  21. Hui KPY, Ho JCW, Cheung MC, Ng KC, Ching RHH, Lai KL, et al. SARS-CoV-2 Omicron variant replication in human bronchus and lung ex vivo. Nature. 2022;603(7902):715-20.  https://doi.org/10.1038/s41586-022-04479-6  PMID: 35104836 
  22. Hughes TD, Subramanian A, Chakraborty R, Cotton SA, Herrera MDPG, Huang Y, et al. The effect of SARS-CoV-2 variant on respiratory features and mortality. Sci Rep. 2023;13(1):4503.  https://doi.org/10.1038/s41598-023-31761-y  PMID: 36934134 
  23. Woodbridge Y, Amit S, Huppert A, Kopelman NM. Viral load dynamics of SARS-CoV-2 Delta and Omicron variants following multiple vaccine doses and previous infection. Nat Commun. 2022;13(1):6706.  https://doi.org/10.1038/s41467-022-33096-0  PMID: 36344489 
  24. Puhach O, Adea K, Hulo N, Sattonnet P, Genecand C, Iten A, et al. Infectious viral load in unvaccinated and vaccinated individuals infected with ancestral, Delta or Omicron SARS-CoV-2. Nat Med. 2022;28(7):1491-500.  https://doi.org/10.1038/s41591-022-01816-0  PMID: 35395151 
  25. Collie S, Champion J, Moultrie H, Bekker L-G, Gray G. Effectiveness of BNT162b2 vaccine against Omicron variant in South Africa. N Engl J Med. 2022;386(5):494-6.  https://doi.org/10.1056/NEJMc2119270  PMID: 34965358 
  26. Stowe J, Andrews N, Kirsebom F, Ramsay M, Bernal JL. Effectiveness of COVID-19 vaccines against Omicron and Delta hospitalisation, a test negative case-control study. Nat Commun. 2022;13(1):5736.  https://doi.org/10.1038/s41467-022-33378-7  PMID: 36180428 
  27. Halford F, Nash S, Tessier E, Kall M, Dabrera G. Variation in reported SARS-CoV-2 cases after testing policy changes. Lancet Infect Dis. 2022;22(10):1418-9.  https://doi.org/10.1016/S1473-3099(22)00572-2  PMID: 36027903 
  28. Norwegian Institute of Public Health (NIPH). Covid-19, influensa og andre luftveisinfeksjoner: Rapport – uke 41 og 42. [COVID-19, influenza and other respiratory infections: report – week 41 and 42]. Oslo: NIPH; 2022. Norwegian. Available from: https://www.fhi.no/publ/2020/koronavirus-ukerapporter/
  29. Government of Portugal. Fim do estado de alerta. [End of alert status]. Lisbon: Government of Portugal; 2022. Portuguese. Available from: https://www.portugal.gov.pt/pt/gc23/comunicacao/noticia?i=fim-do-estado-de-alerta
  30. Statens Serum Institut (SSI). Covid-19 nøgletal. [COVID-19 key figures]. Copenhagen: SSI; 2022 Danish. Available from: https://experience.arcgis.com/experience/aa41b29149f24e20a4007a0c4e13db1d
  31. Spiess K, Gunalan V, Marving E, Nielsen SH, Jørgensen MGP, Fomsgaard AS, et al. , Danish COVID-19 Genome Consortium (DCGC). Rapid and flexible RT-qPCR surveillance platforms to detect SARS-CoV-2 mutations. Microbiol Spectr. 2023;11(1):e0359122.  https://doi.org/10.1128/spectrum.03591-22  PMID: 36625603 
  32. Blomquist PB, Bridgen J, Bray N, O’Connell AM, West D, Groves N, et al. Enhancing epidemiological surveillance of the emergence of the SARS-CoV-2 Omicron variant using spike gene target failure data, England, 15 November to 31 December 2021. Euro Surveill. 2022;27(11):2200143.  https://doi.org/10.2807/1560-7917.ES.2022.27.11.2200143  PMID: 35301981 
  33. Seaman SR, Nyberg T, Overton CE, Pascall DJ, Presanis AM, De Angelis D. Adjusting for time of infection or positive test when estimating the risk of a post-infection outcome in an epidemic. Stat Methods Med Res. 2022;31(10):1942-58.  https://doi.org/10.1177/09622802221107105  PMID: 35695245 
  34. R Core Team. R: A language and environment for statistical computing. Vienna: R Foundation for Statistical Computing; 2020. Available from: https://www.R-project.org
  35. Whittaker R, Greve-Isdahl M, Bøås H, Suren P, Buanes EA, Veneti L. COVID-19 hospitalization among children <18 years by variant wave in Norway. Pediatrics. 2022;150(3):e2022057564.  https://doi.org/10.1542/peds.2022-057564  PMID: 35916036 
  36. Wang L, Berger NA, Kaelber DC, Davis PB, Volkow ND, Xu R. Incidence rates and clinical outcomes of SARS-CoV-2 infection with the Omicron and Delta variants in children younger than 5 years in the US. JAMA Pediatr. 2022;176(8):811-3.  https://doi.org/10.1001/jamapediatrics.2022.0945  PMID: 35363246 
  37. Clark M, Walker B, Bennett E, Herrick A, Kenny S, Gent N. Clinical characteristics of SARS-CoV-2 omicron infection in children under one year. SSRN. 2022 . https://doi.org/10.2139/ssrn.4013461 
  38. Griffith GJ, Morris TT, Tudball MJ, Herbert A, Mancano G, Pike L, et al. Collider bias undermines our understanding of COVID-19 disease risk and severity. Nat Commun. 2020;11(1):5749.  https://doi.org/10.1038/s41467-020-19478-2  PMID: 33184277 
A standardised protocol for relative SARS-CoV-2 variant severity assessment, applied to Omicron BA.1 and Delta in six European countries, October 2021 to February 2022
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=Tommy+Nyberg&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Nyberg Tommy</a>, <a href="/search?value1=Peter+Bager&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bager Peter</a>, <a href="/search?value1=Ingrid+Bech+Svalgaard&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Svalgaard Ingrid Bech</a>, <a href="/search?value1=Dritan+Bejko&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bejko Dritan</a>, <a href="/search?value1=Nick+Bundle&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bundle Nick</a>, <a href="/search?value1=Josie+Evans&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Evans Josie</a>, <a href="/search?value1=Tyra+Grove+Krause&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Krause Tyra Grove</a>, <a href="/search?value1=Jim+McMenamin&option1=author&noRedirect=true" class="nonDisambigAuthorLink">McMenamin Jim</a>, <a href="/search?value1=Jo%C3%ABl+Mossong&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Mossong Joël</a>, <a href="/search?value1=Heather+Mutch&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Mutch Heather</a>, <a href="/search?value1=Ajibola+Omokanye&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Omokanye Ajibola</a>, <a href="/search?value1=Andr%C3%A9+Peralta-Santos&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Peralta-Santos André</a>, <a href="/search?value1=Pedro+Pinto-Leite&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Pinto-Leite Pedro</a>, <a href="/search?value1=Jostein+Starrfelt&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Starrfelt Jostein</a>, <a href="/search?value1=Simon+Thelwall&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Thelwall Simon</a>, <a href="/search?value1=Lamprini+Veneti&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Veneti Lamprini</a>, <a href="/search?value1=Robert+Whittaker&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Whittaker Robert</a>, <a href="/search?value1=John+Wood&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Wood John</a>, <a href="/search?value1=Richard+Pebody&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Pebody Richard</a>, <a href="/search?value1=Anne+M+Presanis&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Presanis Anne M</a></span>. A standardised protocol for relative SARS-CoV-2 variant severity assessment, applied to Omicron BA.1 and Delta in six European countries, October 2021 to February 2022. <a href="/content/ecdc">Euro Surveill.</a> 2023;28(36):pii=2300048. <a href="https://doi.org/10.2807/1560-7917.ES.2023.28.36.2300048" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2023.28.36.2300048</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 19 Jan 2023;&nbsp;&nbsp; <span class="generated">Accepted</span>: 21 May 2023 </span> </p>
/content/10.2807/1560-7917.ES.2023.28.36.2300048
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