Ambrogio Cesa-Bianchi and Andrea Ferrero

Restrictions on activity to curb the spread of Covid-19 led to a shutdown of specific parts of the economy. These lockdown measures can be thought of as a shock that suddenly decreases the supply of affected sectors, which lowers output and increases their price. Guerrieri et al (2020) propose a theoretical model of 'Keynesian supply shocks' where a sectoral supply shock triggers knock-on effects on demand in other sectors which, if strong enough, can lead to a fall in aggregate prices and output – thus resembling an aggregate demand shock. In a recent paper, we provide empirical evidence supporting this hypothesis using pre-Covid data. Our results suggest a different way to look at the Covid crisis and business cycles in general.

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