Early assessment of the impact of mitigation measures on the COVID-19 outbreak in Italy

Abstract

Background: On March 11, 2020, the World Health Organization characterized the novel coronavirus disease 2019 (COVID-19) outbreak as a pandemic. The first cases in Italy were reported on January 30, 2020, and the outbreak quickly escalated. On March 19, 2020, deaths in Italy surpassed those in China. The Italian government implemented progressively restrictive measures leading to a nationwide lockdown on March 8, 2020. This study aimed to assess the impact of mitigation measures implemented in Italy on the spread of COVID-19.

Methods: Publicly available data were used to evaluate changes in the growth curve of the number of patients hospitalized in intensive care (IC) at three time intervals between February 19, 2020, and April 9, 2020, after the implementation of progressive measures: (1) containment and travel restrictions, (2) lockdown of the epicenter of the outbreak, and (3) school closures and nationwide lockdown. The models that showed the highest reliability according to the Akaike information criterion and based on data from the three time intervals were projected to assess how the epidemic would have evolved if no other measure had been implemented.

Results: The most reliable models were (1) exponential, (2) quadratic, and (3) cubic (R² = 0.99, >0.99, and > 0.99 respectively), indicating a progressive decrease in the growth of the curve.

Conclusion: This study suggests the measures were effective in flattening the epidemic curve and bought valuable time, allowing for the number of IC beds to be nearly doubled before the national health system reached maximum capacity.

Keywords: COVID-19; Containment; Intensive care; Mitigation; SARS-CoV-2.

Fig. 1

The number of patients infected with COVID-19 in intensive care (IC) in Italy, from February 19, 2020 to April 9, 2020, and projections of the number of patients in IC if no further measures to control the outbreak had been implemented based on growth curves at three time intervals. Squares: notified number of patients in IC due to COVID-19. Lines: projections based on growth curves. Dotted vertical lines: lockdown of the red zone, school closures, and nationwide lockdown (with a 9 day delay to account for incubation and time from onset of symptoms until hospitalization in IC). Dotted horizontal lines: maximum capacity of IC beds at March 8, 2020 and March 24, 2020. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.) COVID-19, coronavirus disease 2019.