Hostname: page-component-74656f9884-rdgjk Total loading time: 0 Render date: 2026-11-08T04:48:39.867Z Has data issue: false hasContentIssue false

Spatial growth rate of emerging SARS-CoV-2 lineages in England, September 2020–December 2021

Published online by Cambridge University Press:  20 July 2022

M. R. Smallman-Raynor*
Affiliation:
School of Geography, University of Nottingham, Nottingham, UK
A. D. Cliff
Affiliation:
Department of Geography, University of Cambridge, Cambridge, UK
The COVID-19 Genomics UK (COG-UK) Consortium
Affiliation:
https://www.cogconsortium.uk
*
Author for correspondence: M. R. Smallman-Raynor, E-mail: matthew.smallman-raynor@nottingham.ac.uk
Rights & Permissions [Opens in a new window]

Abstract

This paper uses a robust method of spatial epidemiological analysis to assess the spatial growth rate of multiple lineages of SARS-CoV-2 in the local authority areas of England, September 2020–December 2021. Using the genomic surveillance records of the COVID-19 Genomics UK (COG-UK) Consortium, the analysis identifies a substantial (7.6-fold) difference in the average rate of spatial growth of 37 sample lineages, from the slowest (Delta AY.4.3) to the fastest (Omicron BA.1). Spatial growth of the Omicron (B.1.1.529 and BA) variant was found to be 2.81× faster than the Delta (B.1.617.2 and AY) variant and 3.76× faster than the Alpha (B.1.1.7 and Q) variant. In addition to AY.4.2 (a designated variant under investigation, VUI-21OCT-01), three Delta sublineages (AY.43, AY.98 and AY.120) were found to display a statistically faster rate of spatial growth than the parent lineage and would seem to merit further investigation. We suggest that the monitoring of spatial growth rates is a potentially valuable adjunct to outbreak response procedures for emerging SARS-CoV-2 variants in a defined population.

Information

Type
Original Paper
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
Copyright © The Author(s), 2022. Published by Cambridge University Press
Figure 0

Fig. 1. COVID-19 cases in England, September 2020–December 2021. (a) Positive COVID-19 test specimens as recorded by the UK Government. (b) Number of sample genomes of SARS-CoV-2 in the COG-UK database by variant to 18 December 2021. All data are plotted by week of sample collection. Sources: data from GOV.UK Coronavirus (COVID-19) in the UK [17] and COVID-19 Genomics UK (COG-UK) Consortium [18].

Figure 1

Table 1. Estimated rate of spatial growth ($\bar{t}_{LE}$) of sample SARS-CoV-2 lineages in England, September 2020–December 2021

Figure 2

Fig. 2. Spatial leading edges (LE) of the Alpha (B.1.1.7 and Q), Delta (B.1.617.2 and AY) and Omicron (B.1.1.529 and BA) variants in England, September 2020–December 2021. The graphs plot, on a weekly basis, the non-cumulative count (upper) and cumulative proportion (lower) of LTLAs in which each of the three variants was first detected. The horizontal (time) axes are indexed to the epidemiological week of first detection (t = 1) of the corresponding variant. Average curves, formed across the set of sample lineages in Table 1, are plotted for reference.

Figure 3

Fig. 3. Spatial leading edges (LE) of the Alpha (B.1.1.7 and Q), Delta (B.1.617.2 and AY) and Omicron (B.1.1.529 and BA) variants in the LTLAs of England, September 2020–December 2021. Maps are indexed to the epidemiological week of first detection (= week 1) of the corresponding variant and plot the number of weeks to first detection in each LTLA.

Figure 4

Fig. 4. Spatial leadings edges (LE) of the Alpha (B.1.1.7 and Q), Delta (B.1.617.2 and AY) and Omicron (B.1.1.529 and BA) variants in the nine standard regions of England, September 2020–December 2021. Maps plot the average time (in weeks) to first detection of a given variant in each regional subset of LTLAs.

Figure 5

Fig. 5. Estimated rate of spatial growth of sample SARS-CoV-2 lineages in England, September 2020–December 2021. The graph plots values of $\bar{t}_{LE}$ and associated 95% CI from Table 1. Values are ordered from the lowest (left, high values of $\bar{t}_{LE}$) to the highest (right, low values of $\bar{t}_{LE}$) rates of spatial growth. Values are plotted on an inverted vertical scale to facilitate interpretation. The average value of $\bar{t}_{LE}$ for the sample is shown for reference.

Figure 6

Fig. 6. Spatial growth curves for sample Delta sublineages in England, March–December 2021. Curves have been formed in the manner of the lower graphs in Figure 2, with the average curve plotted for reference. Lineages are ordered according to the values of $\bar{t}_{LE}$ in Table 1 and are defined as having relatively high (i.e. low values of $\bar{t}_{LE}$; upper graphs, a) and relatively low (i.e. high values of $\bar{t}_{LE}$; lower graphs, b) rates of spatial growth.

Figure 7

Table 2. Worldwide detection of sample Delta AY lineages with relatively high estimated rates of spatial growth (status: 9 January 2022)