The Evolution of Covid-19 in Italy after the Spring of 2020: An Unpredicted Summer Respite Followed by a Second Wave

Giuseppe De Natale, Lorenzo De Natale, Claudia Troise, Vito Marchitelli, Antonio Coviello, Karen G. Holmberg and Renato Somma
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Giuseppe De Natale: INGV, Osservatorio Vesuviano, 80124 Naples, Italy
Lorenzo De Natale: Medical School, Università Degli Studi di Napoli “Federico II”, 80131 Naples, Italy
Claudia Troise: INGV, Osservatorio Vesuviano, 80124 Naples, Italy
Vito Marchitelli: Department of Mobility, Public Works, Ecology, Environment, Puglia Region Government, 70100 Bari, Italy
Antonio Coviello: CNR-IRISS, 80134 Naples, Italy
Karen G. Holmberg: Gallatin School of Individualized Study, New York University, New York, NY 10003, USA
Renato Somma: INGV, Osservatorio Vesuviano, 80124 Naples, Italy

IJERPH, 2020, vol. 17, issue 23, 1-12

Abstract: The coronavirus (COVID-19) pandemic was particularly invasive in Italy during the period between March and late April 2020, then decreased in both the number of infections and in the seriousness of the illness throughout the summer of 2020. In this work, we measure the severity of the disease by the ratio of Intensive Care Units (ICU) spaces occupied by COVID-19 patients and the number of Active Cases (AC) each month from April to October 2020. We also use the ratio of the number of Deaths (D) to the number of Active Cases. What clearly emerges, from rigorous statistical analysis, is a progressive decrease in both ratios until August, indicating progressive mitigation of the disease. This is particularly evident when comparing March–April with July–August; during the summer period the two ratios became roughly 18 times lower. We test such sharp decreases against possible bias in counting active cases and we confirm their statistical significance. We then interpret such evidence in terms of the well-known seasonality of the human immune system and the virus-inactivating effect of stronger UV rays in the summer. Both ratios, however, increased again in October, as ICU/AC began to increase in September 2020. These ratios and the exponential growth of infections in October indicate that the virus—if not contained by strict measures—will lead to unsustainable challenges for the Italian health system in the winter of 2020–2021.

Keywords: Covid-19 in Italy; summer mitigation; autumn sharp worsening of epidemics (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2020
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