SARS-CoV-2 pandemic: An overview

Abstract

By the end of May 2020, SARS-CoV-2 pandemic caused more than 350,000 deaths worldwide. In the first months, there have been uncertainties on almost any area: infection transmission route, virus origin and persistence in the environment, diagnostic tests, therapeutic approach, high-risk subjects, lethality, and containment policies. We provide an updated summary of the current knowledge on the pandemic, discussing the available evidence on the effectiveness of the adopted mitigation strategies.

Keywords: COVID-19; Containment policies; Diagnostic tests; Epidemiology; Mortality; SARS-CoV-2.

Fig. 1

Average risk of causing severe/lethal COVID-19 of the general, asymptomatic Italian population, in open spaces, during SARS-CoV-2 epidemic months (March, April 2020), under the most pessimistic assumptions. * Official data indicate that, in the first three months of infection (up to May 25, 2020), the overall rate of infected subjects was 0.4 out of 100. Even increasing tenfold this value, asymptomatic persons are approximately half of all the infected subjects. Also, with an overestimated average disease duration of 30 days, only half of the overall number of infected subjects could be actively contagious on a single day. Importantly, these are intended as average prevalence values for the entire country, while some provinces had a completely different epidemiologic scenario, with official cumulative incidence rates as high as 10.8% (Bergamo), or 7.4% (Brescia); and as low as 0.05% (Taranto) or 0.08% (L'Aquila). As the lockdown was introduced in the entire country, these estimates are referred to the whole nation. In some provinces, the final risk of infecting other persons might have been 20 times higher, or 10 times lower.