1887
  1. Home
  2. Eurosurveillance
  3. Volume 27, Issue 10, 10/Mar/2022
  4. Article
Research Open Access
Like 0
Download

Abstract

Background

The Delta variant of SARS-CoV-2 had become predominant globally by November 2021.

Aim

We evaluated transmission dynamics and epidemiological characteristics of the Delta variant in an outbreak in southern China.

Methods

Data on confirmed COVID-19 cases and their close contacts were retrospectively collected from the outbreak that occurred in Guangdong, China in May and June 2021. Key epidemiological parameters, temporal trend of viral loads and secondary attack rates were estimated. We also evaluated the association of vaccination with viral load and transmission.

Results

We identified 167 patients infected with the Delta variant in the Guangdong outbreak. Mean estimates of latent and incubation period were 3.9 days and 5.8 days, respectively. Relatively higher viral load was observed in infections with Delta than in infections with wild-type SARS-CoV-2. Secondary attack rate among close contacts of cases with Delta was 1.4%, and 73.1% (95% credible interval (CrI): 32.9–91.4) of the transmissions occurred before onset. Index cases without vaccination (adjusted odds ratio (aOR): 2.84; 95% CI: 1.19–8.45) or with an incomplete vaccination series (aOR: 6.02; 95% CI: 2.45–18.16) were more likely to transmit infection to their contacts than those who had received the complete primary vaccination series.

Discussion

Patients infected with the Delta variant had more rapid symptom onset compared with the wild type. The time-varying serial interval should be accounted for in estimation of reproduction numbers. The higher viral load and higher risk of pre-symptomatic transmission indicated the challenges in control of infections with the Delta variant.

© Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Loading

Article metrics loading...

/content/10.2807/1560-7917.ES.2022.27.10.2100815
2022-03-10
2024-12-23
/content/10.2807/1560-7917.ES.2022.27.10.2100815
Loading
Loading full text...

Full text loading...

/deliver/fulltext/eurosurveillance/27/10/eurosurv-27-10-5.html?itemId=/content/10.2807/1560-7917.ES.2022.27.10.2100815&mimeType=html&fmt=ahah

References

  1. Latif A, Mullen JL, Alkuzweny M, Tsueng G, Cano M, Haag E, et al. B.1.617.2 lineage report. [Accessed: 10 Jul 2021]. La Jolla: Scripps Research. Available from: https://outbreak.info/situation-reports?pango=B.1.617.2
  2. World Health Organization (WHO). Weekly epidemiological update on COVID-19 - 9 November 2021. Geneva: WHO; 2021. Available from: https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19---9-november-2021
  3. Li Z, Nie K, Li K, Hu Y, Song Y, Kang M, et al. Genome characterization of the first outbreak of COVID-19 Delta variant B.1.617.2 - Guangzhou City, Guangdong Province, China, May 2021. China CDC Wkly. 2021;3(27):587-9.  https://doi.org/10.46234/ccdcw2021.151  PMID: 34594942 
  4. Tada T, Zhou H, Dcosta BM, Samanovic MI, Mulligan MJ, Landau NR. The spike proteins of SARS-CoV-2 B.1.617 and B.1.618 variants identified in India Provide partial resistance to vaccine-elicited and therapeutic monoclonal antibodies. bioRxiv. 2021:2021.05.14.444076 . https://doi.org/10.1101/2021.05.14.444076 
  5. Li B, Deng A, Li K, Hu Y, Li Z, Xiong Q, et al. Viral infection and transmission in a large well-traced outbreak caused by the Delta SARS-CoV-2 variant. medRxiv. 2021:2021.07.07.21260122 . https://doi.org/10.1101/2021.07.07.21260122 
  6. Li Z, Liu F, Cui J, Peng Z, Chang Z, Lai S, et al. Comprehensive large-scale nucleic acid-testing strategies support China’s sustained containment of COVID-19. Nat Med. 2021;27(5):740-2.  https://doi.org/10.1038/s41591-021-01308-7  PMID: 33859409 
  7. Park SW, Sun K, Champredon D, Li M, Bolker BM, Earn DJD, et al. Forward-looking serial intervals correctly link epidemic growth to reproduction numbers. Proc Natl Acad Sci USA. 2021;118(2):e2011548118.  https://doi.org/10.1073/pnas.2011548118  PMID: 33361331 
  8. Ali ST, Wang L, Lau EHY, Xu XK, Du Z, Wu Y, et al. Serial interval of SARS-CoV-2 was shortened over time by nonpharmaceutical interventions. Science. 2020;369(6507):1106-9.  https://doi.org/10.1126/science.abc9004  PMID: 32694200 
  9. Cori A, Ferguson NM, Fraser C, Cauchemez S. A new framework and software to estimate time-varying reproduction numbers during epidemics. Am J Epidemiol. 2013;178(9):1505-12.  https://doi.org/10.1093/aje/kwt133  PMID: 24043437 
  10. Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, et al. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med. 2020;382(13):1199-207.  https://doi.org/10.1056/NEJMoa2001316  PMID: 31995857 
  11. Xin H, Wong JY, Murphy C, Yeung A, Taslim Ali S, Wu P, et al. The incubation period distribution of coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis. Clin Infect Dis. 2021;73(12):2344-52.  https://doi.org/10.1093/cid/ciab501 
  12. Ali ST, Yeung A, Shan S, Wang L, Gao H, Du Z, et al. Serial intervals and case isolation delays for COVID-19: a systematic review and meta-analysis. Clin Infect Dis. 2021;ciab491.  https://doi.org/10.1093/cid/ciab491  PMID: 34037748 
  13. Xin H, Li Y, Wu P, Li Z, Lau EHY, Qin Y, et al. Estimating the latent period of coronavirus disease 2019 (COVID-19). Clin Infect Dis. 2021;ciab746.  https://doi.org/10.1093/cid/ciab746  PMID: 34453527 
  14. Du Z, Xu X, Wu Y, Wang L, Cowling BJ, Meyers LA. Serial interval of COVID-19 among publicly reported confirmed cases. Emerg Infect Dis. 2020;26(6):1341-3.  https://doi.org/10.3201/eid2606.200357  PMID: 32191173 
  15. Volz E, Mishra S, Chand M, Barrett JC, Johnson R, Geidelberg L, et al. Assessing transmissibility of SARS-CoV-2 lineage B.1.1.7 in England. Nature. 2021;593(7858):266-9.  https://doi.org/10.1038/s41586-021-03470-x  PMID: 33767447 
  16. Sun K, Wang W, Gao L, Wang Y, Luo K, Ren L, et al. Transmission heterogeneities, kinetics, and controllability of SARS-CoV-2. Science. 2021;371(6526):eabe2424.  https://doi.org/10.1126/science.abe2424  PMID: 33234698 
  17. Wu P, Liu F, Chang Z, Lin Y, Ren M, Zheng C, et al. Assessing asymptomatic, presymptomatic, and symptomatic transmission risk of severe acute respiratory syndrome coronavirus 2. Clin Infect Dis. 2021;73(6):e1314-20.  https://doi.org/10.1093/cid/ciab271 
  18. He X, Lau EHY, Wu P, Deng X, Wang J, Hao X, et al. Temporal dynamics in viral shedding and transmissibility of COVID-19. Nat Med. 2020;26(5):672-5.  https://doi.org/10.1038/s41591-020-0869-5  PMID: 32296168 
  19. Ren X, Li Y, Yang X, Li Z, Cui J, Zhu A, et al. Evidence for pre-symptomatic transmission of coronavirus disease 2019 (COVID-19) in China. Influenza Other Respir Viruses. 2021;15(1):19-26.  https://doi.org/10.1111/irv.12787  PMID: 32767657 
  20. Hellewell J, Abbott S, Gimma A, Bosse NI, Jarvis CI, Russell TW, et al. Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts. Lancet Glob Health. 2020;8(4):e488-96.  https://doi.org/10.1016/S2214-109X(20)30074-7  PMID: 32119825 
  21. Jing QL, Liu MJ, Zhang ZB, Fang LQ, Yuan J, Zhang AR, et al. Household secondary attack rate of COVID-19 and associated determinants in Guangzhou, China: a retrospective cohort study. Lancet Infect Dis. 2020;20(10):1141-50.  https://doi.org/10.1016/S1473-3099(20)30471-0  PMID: 32562601 
  22. Madewell ZJ, Yang Y, Longini IM Jr, Halloran ME, Dean NE. Factors associated with household transmission of SARS-CoV-2: an updated systematic review and meta-analysis. JAMA Netw Open. 2021;4(8):e2122240.  https://doi.org/10.1001/jamanetworkopen.2021.22240  PMID: 34448865 
  23. Davies NG, Abbott S, Barnard RC, Jarvis CI, Kucharski AJ, Munday JD, et al. Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England. Science. 2021;372(6538):eabg3055.  https://doi.org/10.1126/science.abg3055  PMID: 33658326 
  24. Liu C, Ginn HM, Dejnirattisai W, Supasa P, Wang B, Tuekprakhon A, et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell. 2021;184(16):4220-4236.e13.  https://doi.org/10.1016/j.cell.2021.06.020  PMID: 34242578 
  25. 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 
  26. World Health Organization WHO). WHO target product profiles for COVID-19 vaccines. Version 3. Geneva: WHO; 2020. Available from: https://cdn.who.int/media/docs/default-source/blue-print/who-target-product-profiles-for-covid-19-vaccines.pdf?sfvrsn=1d5da7ca_5&download=true
  27. Public Health England (PHE). Understanding cycle threshold (Ct) in SARS-CoV-2 RT-PCR. A guide for health protection teams. London: PHE; 2020. Available from:https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/926410/Understanding_Cycle_Threshold__Ct__in_SARS-CoV-2_RT-PCR_.pdf
  28. van Kampen JJA, van de Vijver DAMC, Fraaij PLA, Haagmans BL, Lamers MM, Okba N, et al. Duration and key determinants of infectious virus shedding in hospitalized patients with coronavirus disease-2019 (COVID-19). Nat Commun. 2021;12(1):267.  https://doi.org/10.1038/s41467-020-20568-4  PMID: 33431879 
  29. Li XN, Huang Y, Wang W, Jing QL, Zhang CH, Qin PZ, et al. Effectiveness of inactivated SARS-CoV-2 vaccines against the Delta variant infection in Guangzhou: a test-negative case-control real-world study. Emerg Microbes Infect. 2021;10(1):1751-9.  https://doi.org/10.1080/22221751.2021.1969291  PMID: 34396940 
  30. Hodgson SH, Mansatta K, Mallett G, Harris V, Emary KRW, Pollard AJ. What defines an efficacious COVID-19 vaccine? A review of the challenges assessing the clinical efficacy of vaccines against SARS-CoV-2. Lancet Infect Dis. 2021;21(2):e26-35.  https://doi.org/10.1016/S1473-3099(20)30773-8  PMID: 33125914 
Transmission dynamics and epidemiological characteristics of SARS-CoV-2 Delta variant infections in Guangdong, China, May to June 2021
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=Min+Kang&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Kang Min</a>, <a href="/search?value1=Hualei+Xin&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Xin Hualei</a>, <a href="/search?value1=Jun+Yuan&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Yuan Jun</a>, <a href="/search?value1=Sheikh+Taslim+Ali&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Ali Sheikh Taslim</a>, <a href="/search?value1=Zimian+Liang&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Liang Zimian</a>, <a href="/search?value1=Jiayi+Zhang&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Zhang Jiayi</a>, <a href="/search?value1=Ting+Hu&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Hu Ting</a>, <a href="/search?value1=Eric+HY+Lau&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Lau Eric HY</a>, <a href="/search?value1=Yingtao+Zhang&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Zhang Yingtao</a>, <a href="/search?value1=Meng+Zhang&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Zhang Meng</a>, <a href="/search?value1=Benjamin+J+Cowling&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Cowling Benjamin J</a>, <a href="/search?value1=Yan+Li&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Li Yan</a>, <a href="/search?value1=Peng+Wu&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Wu Peng</a></span>. Transmission dynamics and epidemiological characteristics of SARS-CoV-2 Delta variant infections in Guangdong, China, May to June 2021. <a href="/content/ecdc">Euro Surveill.</a> 2022;27(10):pii=2100815. <a href="https://doi.org/10.2807/1560-7917.ES.2022.27.10.2100815" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2022.27.10.2100815</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 13 Aug 2021;&nbsp;&nbsp; <span class="generated">Accepted</span>: 09 Jan 2022 </span> </p>
/content/10.2807/1560-7917.ES.2022.27.10.2100815
/content/10.2807/1560-7917.ES.2022.27.10.2100815
Loading

Data & Media loading...

Supplementary data

Submit comment
Close
Comment moderation successfully completed
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error