Epidemiology: Open Access

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Clinical Risk Factors and Duration of Infectiousness of SARS-CoV-2 Among Symptomatic and Asymptomatic Patients

Aasia Khaliq, Fouzia Ashraf, Saamia Tahir, Shahzeb Javed, Huda Abbas, Saher Shahid

We have investigated the clinical characteristics, duration of infectiousness from onset of symptoms and viral kinetics among moderate, mild and asymptomatic cases. For 181 cases, clinical features that were statistically significant between moderate and mild cases are fever (p-value 0.028), cough (p-value 0.352), runny nose (p-value 0.016), nausea (p-value 0.039), loss of smell and taste (p-value 0.02 each), fatigue (p-value 0.008), muscle ache (p-value 0.004), loss of appetite (p-value 0.041) and contact history (p-value 0.010). Logistic regression showed fever (OR, 4.35; p-value 0.006), cough (OR, 12.38; p-value 0.0001), expectoration (OR, 7.54; 0.003), sore throat (OR, 8.50; 0.0001), SOB (OR, 3.02; p-value 0.034), chills (OR 3.50; p-value 0.0005), diarrhea (OR 2.09; p-value 0.034), headache (OR, 14.80, p-value 0.0001) and loss of appetite (OR, 3.79, p-value 0.034) to be associated with disease severity in moderate cases as compared to mild cases. Median duration of viral shedding from symptoms onset to diagnosis was 6 days (IQ 4-8 days; range 2-10 days) while for the mild cases it was 8 days (IQ 6-10 days; range 4-11 days). The mean Ct value for moderate cases (median 25.03, 95% CI 23.83-26.81) was significantly lower than mild (median 35.93, 95%CI 35.57-36.23) and asymptomatic cases (median 38.92, 95% CI 38.96-40.07) (p-value <0.001) and mild cases from asymptomatic cases (p-value <0.001). The median infectious period for moderate cases was 15 days while for mild and asymptomatic cases it was 10 days each. The estimated mean time from symptom onset to two negative RT-PCR tests for moderate cases was 17.59 days (95% CI 16.39-18.80), mild cases 12.67 days (95% CI 11.11-14.22) and for asymptomatic cases 12.21 days (95% CI 9.40-15.01). Moderate cases took longer time as compared to mild and asymptomatic cases. When stratified by gender, female patients took significantly longer time (p-value <0.0001) to negative RT-PCR test.