Superspreaders, asymptomatics and COVID-19 elimination

A meta-analysis published in 2020 concluded that the rate of asymptomatic transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is 35% lower compared with COVID-19 patients with symptomatic illness. This has also been clearly explained in a seminal study showing that the viral load is the highest in concomitance with symptoms onset, so that the infectiousness of pre-symptomatic or asymptomatic individuals is probably low. Notably, the impact of presymptomatic SARS-CoV-2 transmission seems also rather limited, whereby the secondary attack rate was found to account for only 15% of all secondary COVID-19 cases. Beside the fact that the asymptomatic SARS-CoV-2- positive rate varies greatly depending on many genetic, demographic (ie, age, sex and ethnic origin) and even clinical (eg, time course of disease, comorbidities) variables, an analysis in the official database of the Italian National Institute of Health reveals, for example, that the rate of asymptomatic subjects with SARS-CoV-2 infection approximates 70%. Combined with lower infectiousness, the high prevalence of asymptomatic subjects bearing SARS-CoV-2 infection after release of restrictive practices (eg, lifting of lockdowns) would persuade us to conclude that the possible impact of asymptomatic superspreaders on SARS-CoV-2 transmission would be low and perhaps insufficient to influence or guide future policies aimed at restricting individual freedom.