Assessment of tiered restrictions and a second lockdown on COVID-19 deaths and hospitalisations in England: a modelling study

Status: Paper under peer review | First online: 17-11-2020 | Last update: 18-11-2020

This study has not yet been peer reviewed.

A second wave of COVID-19 cases in Autumn 2020 led to localised, tiered “Alert Level” restrictions and subsequently a second national lockdown in England. We examine the impact of these tiered restrictions and options for lockdowns in terms of stringency, timing and length.

Figure. Contrasting alternative intervention strategies. (a) Type of intervention: baseline epidemic (“Baseline”), tiered restrictions only (tiers), Northern Ireland-type lockdown with schools open (Ld N/o) or with schools closed (Ld N/c), Wales-type lockdown with schools open (Ld W/o) or closed (Ld W/c). Note that the lines for Ld N/c and Ld W/o closely overlap in the top row. (b) Duration of lockdown: with tiered restrictions in place, commencing on 5 November 2020, Wales-type lockdowns with schools open with durations from 0 weeks (No lockdown) to 6 weeks are contrasted. (c) Timing of lockdown: four-week Wales-type lockdowns with schools open starting up to four weeks before or two weeks after 5 November 2020 are contrasted. Top row shows cumulative deaths over time under each scenario. Middle row shows hospital pressure, defined as the population-weighted average number of weeks that an NHS region’s hospital (green) or ICU (orange) bed occupancy exceeds 50% of the peak occupancy for that region during the first wave of COVID-19 in England. Bottom row shows the expected number of weeks that a random individual in England spends under Tier 2, Tier 3, or lockdown restrictions for each scenario. All panels show medians with shaded regions defining 95% confidence intervals.

Methods: We fit an age-structured mathematical model of SARS-CoV-2 transmission to seven months of hospital, antibody, virology and death data across seven NHS England regions to project epidemiological dynamics under various scenarios forward to 31 March 2021. We analyse mobility and social contact data from March–October 2020 to estimate the effect of tiered restrictions in England, and of lockdowns of similar stringency to those implemented in Northern Ireland and Wales in October 2020, applied to England.

Findings: From 1 October 2020 to 31 March 2021, a COVID-19 epidemic without tiered restrictions or a lockdown is projected to result in 195,000 (95% credible interval: 192,000–199,000) hospital admissions and 31,800 (30,200–32,500) deaths, with a peak ICU occupancy of 3,030 (2,960– 3,130) beds. The introduction of tiered restrictions on 14 October 2020 is projected to reduce the burden to 168,000 (164,000–171,000) hospital admissions and 26,500 (25,400–27,500) deaths with a peak ICU occupancy of 2,460 (2,400–2,530) beds. A four-week Wales-type lockdown with schools open, starting on 5 November 2020—similar to lockdown measures announced in England—is projected to further reduce the burden to 116,000 (114,000– 118,000) hospital admissions and 18,200 (17,700–18,700) deaths, with a peak ICU occupancy of 1,770 (1,710–1,840) beds. Closing schools as well would likely further reduce deaths to 15,100 (14,700 - 15,400), but would make very little difference to peak ICU demand (1,740 (1,680 - 1,810)). We find that a lockdown of greater than 4 weeks reduces deaths but does not substantially reduce pressure on hospital services, and that an earlier lockdown reduces deaths and hospitalisations in the short term but leads to a faster resurgence in cases after January 2021.

Interpretation: Lockdown measures consistently outperform less stringent restrictions in reducing cumulative deaths. Amongst the scenarios modelled, the policy adopted in England appears to be a reasonable compromise—given the current epidemiological situation—as it reduces pressure on the health service to a similar extent to longer or more stringent lockdowns, is well-timed to suppress deaths over the winter period and keeps schools open.

Read the full pre-print here.