Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 29, Number 10—October 2023
Research

Emergence of SARS-CoV-2 Delta Variant and Effect of Nonpharmaceutical Interventions, British Columbia, Canada

Y.L. Elaine ChanComments to Author , Michael A. Irvine, Natalie Prystajecky, Hind Sbihi, Marsha Taylor, Yayuk Joffres, Andrea Schertzer, Caren Rose, Louise Dyson, Edward M. Hill, Michael Tildesley, John R. Tyson, Linda M.N. Hoang, and Eleni Galanis
Author affiliations: British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada (Y.L.E. Chan, M.A. Irvine, N. Prystajecky, H. Sbihi, M. Taylor, Y. Joffres, A. Schertzer, C. Rose, J.R. Tyson, L.M.N. Hoang, E. Galanis); Public Health Agency of Canada, Ottawa, Ontario, Canada (Y.L.E. Chan, A. Schertzer); Simon Fraser University, Burnaby, British Columbia, Canada (M.A. Irvine); University of British Columbia, Vancouver (N. Prystajecky, H. Sbihi, C. Rose, L.M.N. Hoang, E. Galanis); University of Warwick, Coventry, UK (L. Dyson, E.M. Hill, M. Tildesley); Joint UNIversities Pandemic and Epidemiological Research (L. Dyson, E.M. Hill, M. Tildesley)

Main Article

Figure 2

Epidemiologic curve of SARS-CoV-2 Delta VOC cases in British Columbia, Canada, by patient travel history, March 1–June 30, 2021 (n = 1,178). Delta VOC cases classified as having no known travel include 8 cases with missing travel information. Effective at 8:30 p.m. on April 22, 2021 (labeled as April 23 on figure), the government of Canada implemented a ban on all direct commercial and private passenger flights from India and Pakistan (21). The travel ban on direct flights from India remained in effect for the rest of the study period, whereas the ban on direct flights from Pakistan was in effect until June 21, 2021 (21,22). Travelers arriving before the federal travel ban were required to complete day 10 postarrival qPCR testing; as a result, travelers arriving before April 23 might have had specimens collected up to May 2, 2021. BC, British Columbia; qPCR, quantitative PCR; VOC, variant of concern.

Figure 2. Epidemiologic curve of SARS-CoV-2 Delta VOC cases in British Columbia, Canada, by patient travel history, March 1–June 30, 2021 (n = 1,178). Delta VOC cases classified as having no known travel include 8 cases with missing travel information. Effective at 8:30 p.m. on April 22, 2021 (labeled as April 23 on figure), the government of Canada implemented a ban on all direct commercial and private passenger flights from India and Pakistan (21). The travel ban on direct flights from India remained in effect for the rest of the study period, whereas the ban on direct flights from Pakistan was in effect until June 21, 2021 (21,22). Travelers arriving before the federal travel ban were required to complete day 10 postarrival qPCR testing; as a result, travelers arriving before April 23 might have had specimens collected up to May 2, 2021. BC, British Columbia; qPCR, quantitative PCR; VOC, variant of concern.

Main Article

References
  1. World Health Organization. Tracking SARS-CoV-2 variants [cited 2022 Dec 10]. https://www.who.int/en/activities/tracking-SARS-CoV-2-variants
  2. Campbell  F, Archer  B, Laurenson-Schafer  H, Jinnai  Y, Konings  F, Batra  N, et al. Increased transmissibility and global spread of SARS-CoV-2 variants of concern as at June 2021. Euro Surveill. 2021;26:2100509.
  3. Mlcochova  P, Kemp  SA, Dhar  MS, Papa  G, Meng  B, Ferreira  IATM, et al.; Indian SARS-CoV-2 Genomics Consortium (INSACOG). Genotype to Phenotype Japan (G2P-Japan) Consortium; CITIID-NIHR BioResource COVID-19 Collaboration. SARS-CoV-2 B.1.617.2 Delta variant replication and immune evasion. Nature. 2021;599:114–9.
  4. Elbe  S, Buckland-Merrett  G. Data, disease and diplomacy: GISAID’s innovative contribution to global health. Glob Chall. 2017;1:33–46.
  5. GISAID. Tracking of hCoV-19 variants [cited 2022 Dec 10]. https://www.gisaid.org/hcov19-variants
  6. BC Centre for Disease Control. Weekly update on variants of concern (VOC): Sep 17, 2021 [cited 2022 Dec 10]. http://www.bccdc.ca/Health-Info-Site/Documents/VoC/VoC_weekly_09172021.pdf
  7. Public Health England. SARS-CoV-2 variants of concern and variants under investigation in England: Technical briefing 23 [cited 2021 Sep 19]. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1018547/Technical_Briefing_23_21_09_16.pdf
  8. 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;397:2461–2.
  9. Public Health Scotland. Tracking the Delta variant in Scotland [cited 2023 Jun 25]. https://publichealthscotland.scot/our-blog/2021/november/tracking-the-delta-variant-in-scotland
  10. Earnest  R, Uddin  R, Matluk  N, Renzette  N, Turbett  SE, Siddle  KJ, et al.; New England Variant Investigation Team. Comparative transmissibility of SARS-CoV-2 variants Delta and Alpha in New England, USA. Cell Rep Med. 2022;3:100583.
  11. Office of the Premier. Three-week circuit breaker begins now to bend the curve, protect people [cited 2022 Dec 10]. https://news.gov.bc.ca/releases/2021PREM0023-000578
  12. Scientific Advisory Group for Emergencies. SPI-M-O: summary of further modelling of easing restrictions–roadmap step 4 on 19th July 2021, 7 July 2021 [cited 2021 Aug 6]. https://www.gov.uk/government/publications/spi-m-o-summary-of-further-modelling-of-easing-restrictions-roadmap-step-4-on-19-july-2021-7-july-2021
  13. UK Health Security Agency. Coronavirus (COVID-19) in the UK: cases in England [cited 2022 Feb 01]. https://coronavirus.data.gov.uk/details/cases?areaType=nation&areaName=England
  14. BC Centre for Disease Control. British Columbia (BC) COVID-19 situation report: week 28: July 11–July 17, 2021 [cited 2022 Dec 10]. http://www.bccdc.ca/Health-Info-Site/Documents/COVID_sitrep/Week_28_2021_BC_COVID-19_Situation_Report.pdf
  15. UK Health Security Agency. Coronavirus (COVID-19) in the UK: vaccinations in England [cited 2021 Aug 6]. https://coronavirus.data.gov.uk/details/vaccinations?areaType=nation&areaName=England
  16. Department of Health & Social Care. Policy paper: UK COVID-19 vaccines delivery plan [cited 2022 May 15]. https://www.gov.uk/government/publications/uk-covid-19-vaccines-delivery-plan/uk-covid-19-vaccines-delivery-plan#supply-1
  17. Anderson  SC, Edwards  AM, Yerlanov  M, Mulberry  N, Stockdale  JE, Iyaniwura  SA, et al. Quantifying the impact of COVID-19 control measures using a Bayesian model of physical distancing. PLOS Comput Biol. 2020;16:e1008274.
  18. Public Health England. SARS-CoV-2 variants of concern and variants under investigation in England: Technical briefing 19 [cited 2021 Aug 6]. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1005517/Technical_Briefing_19.pdf
  19. Anderson  SC, Edwards  AM, Yerlanov  M, Mulberry  N, Stockdale  JE, Falcao  RC, et al. Bayesian SEIR modelling for multivariate COVID-19 case data [cited 2022 Dec 10]. https://seananderson.github.io/covidseir/index.html
  20. O'Toole  Á, Scher  E, Underwood  A, Jackson  B, Hill  V, McCrone  JT, et al. Assignment of epidemiological lineages in an emerging pandemic using the pangolin tool. Virus Evol. 2021 Jul 30;7(2):veab064. PMID 34527285
  21. Transport Canada. Government of Canada suspends flights from India and Pakistan [cited 2022 Dec 10]. https://www.canada.ca/en/transport-canada/news/2021/04/government-of-canada-suspends-flights-from-india-and-pakistan.html
  22. Public Health Agency of Canada. Government of Canada's first phase to easing border measures for travellers entering Canada [cited 2022 Dec 10]. https://www.canada.ca/en/public-health/news/2021/06/government-of-canadas-first-phase-to-easing-border-measures-for-travellers-entering-canada3.html
  23. Wells  CR, Sah  P, Moghadas  SM, Pandey  A, Shoukat  A, Wang  Y, et al. Impact of international travel and border control measures on the global spread of the novel 2019 coronavirus outbreak. Proc Natl Acad Sci U S A. 2020;117:7504–9.
  24. Lopez Bernal  J, Andrews  N, Gower  C, Gallagher  E, Simmons  R, Thelwall  S, et al. Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant. N Engl J Med. 2021;385:585–94.
  25. Pouwels  KB, Pritchard  E, Matthews  PC, Stoesser  N, Eyre  DW, Vihta  KD, et al. Effect of Delta variant on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK. Nat Med. 2021;27:2127–35.
  26. McCrone  JT, Hill  V, Bajaj  S, Pena  RE, Lambert  BC, Inward  R, et al.; COVID-19 Genomics UK (COG-UK) Consortium. Context-specific emergence and growth of the SARS-CoV-2 Delta variant. Nature. 2022;610:154–60.
  27. Adu  P, Binka  M, Mahmood  B, Jeong  D, Buller-Tylor  T, Jean Damascene  M, et al. Quantifying contact patterns: development and characteristics of the British Columbia COVID-19 population mixing patterns survey. Int J Infect Dis. 2022;116:S30–1.
  28. Scott  N, Saul  A, Spelman  T, Stoove  M, Pedrana  A, Saeri  A, et al. The introduction of a mandatory mask policy was associated with significantly reduced COVID-19 cases in a major metropolitan city. PLoS One. 2021;16:e0253510.
  29. Office of the Premier. B.C. shifts to Step 3 of restart plan [cited 2022 Dec 10]. https://news.gov.bc.ca/releases/2021PREM0043-001268
  30. Lemey  P, Ruktanonchai  N, Hong  SL, Colizza  V, Poletto  C, Van den Broeck  F, et al. Untangling introductions and persistence in COVID-19 resurgence in Europe. Nature. 2021;595:713–7.
  31. Russell  A, O’Connor  C, Lasek-Nesselquist  E, Plitnick  J, Kelly  JP, Lamson  DM, et al. Spatiotemporal analyses of 2 co-circulating SARS-CoV-2 variants, New York state, USA. Emerg Infect Dis. 2022;28:650–9.
  32. UK Health Security Agency. Coronavirus (COVID-19) in the UK: testing in England [cited 2022 Jul 15]. https://coronavirus.data.gov.uk/details/testing?areaType=nation&areaName=England

Main Article

Page created: August 07, 2023
Page updated: September 20, 2023
Page reviewed: September 20, 2023
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
file_external