Modelling the impact of the tier system on SARS-CoV-2 transmission in the UK between the first and second national lockdowns.

Autor: Laydon DJ; Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK d.laydon@imperial.ac.uk., Mishra S; Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK., Hinsley WR; Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK., Samartsidis P; MRC Biostatistics Unit, Cambridge Institute of Public Health, University of Cambridge, Cambridge, UK., Flaxman S; Department of Mathematics and Data Science Institute, Imperial College London, London, UK., Gandy A; Department of Mathematics, Imperial College London, London, UK., Ferguson NM; Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK., Bhatt S; Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK.
Jazyk: angličtina
Zdroj: BMJ open [BMJ Open] 2021 Apr 22; Vol. 11 (4), pp. e050346. Date of Electronic Publication: 2021 Apr 22.
DOI: 10.1136/bmjopen-2021-050346
Abstrakt: Objective: To measure the effects of the tier system on the COVID-19 pandemic in the UK between the first and second national lockdowns, before the emergence of the B.1.1.7 variant of concern.
Design: This is a modelling study combining estimates of real-time reproduction number R t (derived from UK case, death and serological survey data) with publicly available data on regional non-pharmaceutical interventions. We fit a Bayesian hierarchical model with latent factors using these quantities to account for broader national trends in addition to subnational effects from tiers.
Setting: The UK at lower tier local authority (LTLA) level. 310 LTLAs were included in the analysis.
Primary and Secondary Outcome Measures: Reduction in real-time reproduction number R t .
Results: Nationally, transmission increased between July and late September, regional differences notwithstanding. Immediately prior to the introduction of the tier system, R t averaged 1.3 (0.9-1.6) across LTLAs, but declined to an average of 1.1 (0.86-1.42) 2 weeks later. Decline in transmission was not solely attributable to tiers. Tier 1 had negligible effects. Tiers 2 and 3, respectively, reduced transmission by 6% (5%-7%) and 23% (21%-25%). 288 LTLAs (93%) would have begun to suppress their epidemics if every LTLA had gone into tier 3 by the second national lockdown, whereas only 90 (29%) did so in reality.
Conclusions: The relatively small effect sizes found in this analysis demonstrate that interventions at least as stringent as tier 3 are required to suppress transmission, especially considering more transmissible variants, at least until effective vaccination is widespread or much greater population immunity has amassed.
Competing Interests: Competing interests: None declared.
(© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.)
Databáze: MEDLINE
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