The prevalence of asymptomatic and symptomatic COVID-19 in a cohort of quarantined subjects

• Published in: International journal of infectious diseases Vol. 102; pp. 285 - 288
• Main Authors: Al-Qahtani, Manaf, AlAli, Salman, AbdulRahman, AbdulKarim, Salman Alsayyad, Adel, Otoom, Sameer, Atkin, Stephen L.
• Format: Journal Article
• Language: English
• Published: Canada Elsevier Ltd 01.01.2021; The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases; Elsevier
• Subjects: Adult; Aged; Aged, 80 and over; Asymptomatic Infections - epidemiology; Bahrain - epidemiology; Cohort Studies; COVID-19; COVID-19 - diagnosis; COVID-19 - epidemiology; COVID-19 - prevention & control; COVID-19 Testing; Female; Humans; Male; Middle Aged; Prevalence; Quarantine; SARS-CoV-2; Screening; Symptoms; Bahrain; COVID-19; Screening; SARS-CoV-2; Symptoms
• ISSN: 1201-9712; 1878-3511; 1878-3511
• DOI: 10.1016/j.ijid.2020.10.091

•2714 individuals underwent mandatory quarantine.•136 individuals were SARS-CoV-2 positive on arrival, of whom the majority (92) were asymptomatic.•A further 52 individuals became SARS-CoV-2 positive over a 14-day period.•24 subjects found to be SARS-CoV-2 positive at day 14 remained asymptomatic until viral clearance.•Asymptomatic patients with COVID-19 were more prevalent than those exhibiting symptoms, and are an infection reservoir. The frequency of asymptomatic SARS-CoV-2 infection with viral spread is unclear. Asymptomatic SARS-CoV-2 infection development and progression was investigated in subjects undergoing mandatory quarantine on airport arrival. 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. 188/2714 (6.9%) patients became SARS-CoV-2 positive. On arrival, 136/188 tested positive, with 44/188 (23.4%) symptomatic and 92/188 (48.9%) asymptomatic. 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 symptomatic and asymptomatic patients (12.6 ± 1.0 days and 12.1 ± 0.4 days, respectively). Of the 52/188 (27.7%) testing negative on arrival, 27/52 subsequently became positive and developed symptoms 2–13 days after arrival. 25/188 (13.3%) remained asymptomatic and tested positive at day 14, with viral testing undertaken every 2 days in these subjects; of these, 24 remained asymptomatic, with viral clearance at 9.4 ± 0.7 days — less than for those who were asymptomatic on arrival (p < 0.002). Asymptomatic patients with COVID-19 were more prevalent than those exhibiting symptoms, and are an infection reservoir.