Unexpected volume of Google searches for COVID-19 symptoms in the prepandemic period in Lombardia, Italy

Abstract

Background: Uncertainty still surrounds the nature and origin of the ongoing coronavirus disease 2019 (COVID-19) pandemic outbreak, especially concerning the most probable date of spill over and worldwide propagation.Methods: An electronic search was carried out on Google Trends, with the Italian search terms “febbre” (fever), “tosse” (cough) and “raffreddore” (cold), which are among the most commonly reported COVID-19 symptoms in Italy. The search period was comprised between June 2019 and February 2020, and was limited to the area of the Lombardia region. The number of national influenza cases was also concomitantly retrieved from the Italian Network of Influenza Surveillance.Results: The trend of Google searches for “febbre” (fever), “tosse” (cough) and “raffreddore” (cold) seemed to mirror that of influenza cases, but only after the second week of November 2020. An unexpected peak of Google searches for these symptoms could be noted between the first week of September and the last week of October. This anomalous volume of Google searches could not be directly attributed to influenza spread. This increase was significantly higher compared to the same period of the previous year 2018 (20.4±15.0%;p=0.020). The volumes of Google searches for the three symptoms were also significantly inter-correlated (correlation coefficients between 0.66-0.83;all p<0.001).Conclusions: The results of our analysis seem to confirm that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may have started to circulate in Italy, and more specifically in the region of Lombardia, earlier before the overt pandemic period, probably already at the beginning of September 2019.