Research

Impact of community asymptomatic rapid antigen testing on covid-19 related hospital admissions: synthetic control study

Xingna Zhang, Ben Barr, Mark Green, et al

BMJ 2022; 379 doi: https://doi.org/10.1136/bmj-2022-071374 (Published 23 November 2022)Cite this as: BMJ 2022;379:e071374

Abstract

Objective To analyse the impact of voluntary rapid testing for SARS-CoV-2 antigen in Liverpool city on covid-19 related hospital admissions.

Design Synthetic control analysis comparing hospital admissions for small areas in the intervention population with a group of control areas weighted to be similar for past covid-19 related hospital admission rates and sociodemographic factors.

Setting Liverpool city, UK, 6 November 2020 to 2 January 2021, under the intervention of Covid-SMART (systematic meaningful asymptomatic repeated testing) voluntary, open access supervised self-testing with lateral flow devices, compared with control areas selected from the rest of England.

Population General population of Liverpool (n=498 042) and a synthetic control population from the rest of England.

Main outcome measure Weekly covid-19 related hospital admissions for neighbourhoods in England.

Results The introduction of community testing was associated with a 43% (95% confidence interval 29% to 57%) reduction (146 (96 to 192) in total) in covid-19 related hospital admissions in Liverpool compared with the synthetic control population (non-adjacent set of neighbourhoods with aggregate trends in covid-19 hospital admissions similar to Liverpool) for the initial period of intensive testing with military assistance in national lockdown from 6 November to 3 December 2020. A 25% (11% to 35%) reduction (239 (104 to 333) in total) was estimated across the overall intervention period (6 November 2020 to 2 January 2021), involving fewer testing centres, before England’s national roll-out of community testing, after adjusting for regional differences in tiers of covid-19 restrictions from 3 December 2020 to 2 January 2021.

Box 1

Timeline of Covid-SMART community testing pilot in Liverpool

October 2020

• 14 October
• The new three tier system of covid-19 restrictions begins in England, with Liverpool City Region in tier 3, the highest level of restrictions at the time
• 31 October
• The UK government offers Liverpool mass testing with military assistance

November 2020

• 1 November
• Liverpool City Council Covid-19 Strategic Coordination Group with Mersey Resilience Forum accepts in principle but with the freedom to develop a more targeted approach
• 2 November
• The military arrives in Liverpool to establish test sites
• 5 November
• National lockdown; a communications drive begins in Liverpool on testing, including an interactive map of testing sites and waiting times on Liverpool City Council’s website, and articles put out via digital media in response to testing uptake, feedback on engagement at testing sites, analysis of social media, and commissioned surveys
• 6 November
• Six sites open for lateral flow testing (alongside mobile units for polymerase chain reaction (PCR) testing of people with symptoms)
• 7 November
• Sixteen sites open for lateral flow testing
• 10 November
• First meeting of Department of Health and Social Care’s convened evaluation steering group. Schools-based testing starts
• 11 November
• Capacity increased: 37 community sites plus schools, home PCR kits delivered (one-off, unsolicited mailing to sample households), local evaluation group established
• 20 November
• Reconfiguration of resources: 15 popular testing sites kept, other resources redeployed to smaller sites in low uptake areas
• 23 November
• System for confirmatory PCR changed from national communication and delivery of a home test kit to swabbing at one designated local testing site (with swab kits sent to residents’ homes if they could not travel) and an invitation message tailored to the local area

December 2020

• 2 December
• Liverpool moved into tier 2, with all surrounding regions in higher tiers or with more restrictions
• 3 December
• Handover of management of asymptomatic testing sites from military to Liverpool City Council contractors; targeting becomes more focused as the pilot moves to Liverpool Covid-SMART brand and adapts to fewer covid-19 restrictions
• Pilot of visits to care homes in Liverpool begins, and the communications plan shifts priority to test-before-you-go for implementation as the population returned to high transmission risk settings (eg, hairdressers)
• Liverpool City Region roll-out of Covid-SMART begins
• 4 December
• Test-to-release for some key workers begins
• 17 December
• More areas, including Cheshire and Warrington, move into tier 2. Hotels in Liverpool booked heavily with people from London
• 31 December
• Move back into tier 3, with all surrounding regions in tier 4

January 2021

• 4 January
• National lockdown
• National roll-out of community testing begins

Conclusions The city-wide pilot of community based asymptomatic testing for SARS-CoV-2 was associated with substantially reduced covid-19 related hospital admissions. Large scale asymptomatic rapid testing for SARS-CoV-2 could help reduce transmission and prevent hospital admissions.