The prevalence of asymptomatic and symptomatic COVID19 disease in a cohort of quarantined subjects.

Abstract Background The frequency of asymptomatic SARS-CoV-2 infection with viral spread is unclear. Here, we investigated asymptomatic SARS-CoV-2 infection development and progression in subjects undergoing mandatory quarantine on airport arrival. Methods 2714 subjects were tested for SARS-CoV-2 and all were quarantined for 2 weeks. Viral retesting was undertaken on symptom development and routinely at 14 days if asymptomatic. Asymptomatic positive patients underwent viral testing every 2 days to determine viral clearance. Results 188/2714(6.9%) patients became SARS-CoV-2 positive. On arrival, 44/188(23.4%) testing positive were symptomatic and 92/188(48.9%) were asymptomatic (136/188 positive on arrival); all 92 patients remained asymptomatic and were retested every 2-days until viral clearance. 2526 quarantined subjects remained virus free at 14-days. Viral clearance did not differ between these symptomatic and asymptomatic patients (12.6 ± 1.0days and 12.1 ± 0.4days, respectively). Of the 52/188(27.7%) testing negative on arrival, 27/52 became positive and developed symptoms from day 2 to day 13 following arrival. 25/188(13.3%) subjects remained asymptomatic and tested positive at day 14; viral testing was undertaken every 2 days in these subjects, 24/188(12.8%) remained asymptomatic with viral clearance (9.4 ± 0.7days) less than those asymptomatic on arrival(p  Conclusion Asymptomatic patients with COVID-19 were more prevalent than those exhibiting symptoms and are an infection reservoir.