Across the world, there have been a wide range of responses to the COVID-19 pandemic. In some countries, such as China, India or South Africa, governments have moved aggressively to shut down the economy and enforce strict stay-at-home orders. In other cases, such as Italy or Spain, governments initially prevaricated, but have eventually implemented equally severe lockdown measures as the crisis has spun out of control. Then finally, there are those countries such as Sweden, the United States and Brazil which have stopped short of a full national lockdown as the case count has risen.
This variation in policy responses raises a series of critical questions. First, given the vast economic and social cost of implementing lockdown orders, are they proving effective? Second, if so, how long do they take? And finally, when can such measures safely be relaxed, either in whole or in part?
Figure 1. Severity of Lockdowns (Policy Stringency) Over Time.
Width of Lines Reflects Log Number of Diagnosed Covid-19 Cases Per 100,000.
The first of these questions can be dealt with fairly simply: if by effective, we mean capable of delivering demonstrable reductions in the rate of spread of COVID-19, then the answer is yes. This should not be wholly surprising. A society in which the number of social interactions is cut to a fraction of its former rate is one in which the possibility of contagion is vastly reduced. Any other outcome would struggle for an explanation, and perhaps cause us to entirely revise our understanding of how the novel coronavirus is spread.
There is, however, an unfortunate caveat: due to the long incubation period of COVID-19, there is a commensurably long lag between the implementation of lockdown measures and their observed effect. This is compounded by the absence of mass testing, which means most cases are not officially diagnosed until the second week of the illness, once symptoms have progressed to a stage that patients seek hospital care.
This long lag time can be visualised if we take the change in the rate of daily diagnosed cases at 7 days, 10 days, 14 days, and 21 days following the imposition of lockdown measures. Obviously there is a problem of causal inference here, as the degree of policy severity might be expected to result from the extent to which the contagion has gone pandemic (though the correlation between these two variables is substantially lower than one might expect). Nonetheless, what becomes apparent is that on average it takes around three weeks for lockdowns to begin showing through in an observable reduction in new cases.
Figure 2. Changes in Daily Net Active Diagnosed Covid-19 Cases at Different Levels of Policy Stringency, After 7, 10, 14 and 21 Days.
This leads, inevitably, to the third question. Once lockdown measures have begun to show effectiveness, at what point can we begin to implement a phased drawdown, allowing us to eventually “return to normal”? Such measures will inevitably be taken piecemeal, and in combination with behavioural and technological measures, such as the mass provision of personal protective equipment, more widespread testing, temperature detection, and use of social tracking devices and applications. This, together with uncertainty regarding the number of asymptomatic cases (and hence regarding any existing degree of “herd immunity”), means that we are likely to find this out only in practice, once countries begin easing restrictions and the effects become known.
Thus far, however, the signs are mixed at best. In only a few countries – China, Qatar and Indonesia among them – have authorities begun to relax some elements of their lockdown orders so far. Hong Kong has seen a spike in new infections in recent weeks, while Qatar’s relaxation does not appear to be going well since it was recently implemented. This implies that we are very likely in for a long journey in getting our economies and lives back to a state of full normality – a journey that may be better measured in months than in days.
Figure 3 – Period of Lockdown and Net New COVID-19 Cases in Qatar