Precautionary breaks: planned, limited duration circuit breaks to control the prevalence of COVID-19

Abstract

The COVID-19 pandemic in the UK has been characterised by periods of exponential growth and decline, as different non-pharmaceutical interventions (NPIs) are brought into play. During the early uncontrolled phase of the outbreak (early March 2020) there was a period of prolonged exponential growth with epidemiological observations such as hospitalisation doubling every 3-4 days (growth rate r≈0.2). The enforcement of strict lockdown measures led to a noticeable decline in all epidemic quantities (r≈-0.06) that slowed during the summer as control measures were relaxed (r≈-0.02). Since August, infections, hospitalisations and deaths have been rising (precise estimation of the cur-rent growth rate is difficult due to extreme regional heterogeneity and temporal lags between the different epidemiological observations) and various NPIs have been applied locally throughout the UK in response. Controlling any rise in infection is a compromise between public health and societal costs, with more stringent NPIs reducing cases but damaging the economy and restricting freedoms. Currently, NPI imposition is made in response to the epidemiological state, are of indefinite length and are often imposed at short notice, greatly increasing the negative impact. An alternative approach is to consider planned, limited duration periods of strict NPIs aiming to purposefully reduce prevalence before such emergency NPIs are required. These 'precautionary breaks' may offer a means of keeping control of the epidemic, while their fixed duration and the forewarning may limit their society impact. Here, using simple analysis and age-structured models matched to the unfolding UK epidemic, we investigate the action of precautionary breaks. In particular we consider their impact on the prevalence of infection, as well as the total number of predicted hospitalisations and deaths. We find that precautionary breaks provide the biggest gains when the growth rate is low, but offer a much needed brake on increasing infection when the growth rate is higher, potentially allowing other measures (such as contact tracing)to regain control.

Association of tiered restrictions and a second lockdown with COVID-19 deaths and hospital admissions in England: a modelling study

“… 15 Another study looking at short-term, so-called circuit breaker interventions in the UK found that such interventions have the biggest impact when the growth rate is low. 16 The authors concluded that such interventions are not long-term solutions but can buy time to improve other control measures, such as testing, contact tracing and isolation, or introduction of a vaccine.…”

Low case numbers enable long-term stable pandemic control without lockdowns

“…We show that a lockdown is either effective within a few weeks, or tends to fail its aim. If effective, recurring lockdowns are not necessary — contrary to the oscillating dynamics previously presented in the context of circuit breakers 4;5;6 , and contrary to a regime with high case numbers — if moderate contact reductions are maintained. Hence, at low case numbers, the control is easier, and more freedom can be granted.…”

“…Once the number of new infections has overwhelmed the TTI system, re-establishing control can be challenging. A recent suggestion is the application of a circuit breaker 4;5;6 , a short lockdown to significantly lower the number of daily new infections. Already during the first wave, lockdowns have proven capable to lower case numbers by a factor 2 or more every week (corresponding to an observed reproduction number of .…”

Vaccination and Non-Pharmaceutical Interventions: When can the UK relax about COVID-19?

“…We adapt an existing age and regionally structured model of SARS-COV-2 dynamics that has been matched to UK data [12,13] to include the consequences of vaccination [11]. The model captures the historic trends of infection, hospitalisation and deaths in the UK, including the scale of the first and second waves.…”