Lombardy, Italy: COVID-19 second wave less severe than the first? A preliminary investigation

Abstract The much-heralded second wave of coronavirus disease (COVID-19) has arrived in Italy. Right now, one of the main questions about COVID-19 in Italy is whether the second wave will be less severe than the first. Currently, the answer to this question remains open. According to the Italian Ministry of Health website (COVID-19 – Situation in Italy), it would appear that in Italy the COVID-19 second wave is less severe and deadly than the first one was. However, this difference could be affected by several factors, including the different number of swabs performed in the two waves, as it is approximately seven to eight times higher in the second wave. Therefore, it is not yet clear whether the COVID-19 second wave in Italy, specifically in Lombardy, is less severe and deadly than the first wave.In order to answer this challenging question, we decided to quantify the radiographic severity of COVID-19 pneumonia during the second wave and compare it with that of the first wave. In addition, to further test whether the severity of the second wave is indeed lower than that of the first one, we compared the use of mechanical ventilation between the two waves.