…Within 8 months, SARS was controlled …. Within 5 months, SARS-CoV-2 has infected more than 2.6 million people ….
What explains these differences in transmission and spread? A key factor
in the transmissibility of Covid-19 is the high level of SARS-CoV-2
shedding in the upper respiratory tract,1
even among presymptomatic patients, which distinguishes it from SARS-CoV-1, where replication occurs mainly in the lower respiratory
Viral loads with SARS-CoV-1, which are associated with symptom onset, peak a median of 5 days later than viral loads with SARS-CoV-2, which makes symptom-based detection of infection more effective in the case of
With influenza, persons with asymptomatic disease generally have lower
quantitative viral loads in secretions from the upper respiratory tract
than from the lower respiratory tract and a shorter duration of viral
shedding than persons with symptoms,4 which decreases the risk of transmission from paucisymptomatic persons (i.e., those with few symptoms).