Time to Negativity and Factors Associated with Persistent Reverse Transcription-Polymerase Chain Reaction Positivity among Asymptomatic and Mildly Symptomatic Covid-19 Patients

Abstract

BACKGROUND The Covid-19 infection caused by SARS-CoV-2 has spread rapidly across the world & has become a global public health emergency. Infected patients tend to carry the virus for a longer period of time, which requires an early isolation and monitoring. Information on persistent RT-PCR positivity and time to negativity are lacking in our population. We wanted to assess the prevalence of persistent RT-PCR positivity, time to a negative test and factors related to it in our population. METHODS This is a retrospective medical record based observational study conducted among lab confirmed and admitted Covid-19 patients. After admission, repeat oropharyngeal swabs were taken at specific time intervals that varied from 3 - 5 days. A persistent RT-PCR positivity was defined as more than 3 repeat positive RT-PCR tests in a patient. RESULTS 118 Covid-19 positive patients were included in the study. Mean age was 40.58 yrs. (SD, 11.9 years). Median number of repeat RT-PCR tests was 3 (IQR, 2 – 4 repeats). Persistent RT-PCR positivity was seen in 15 (12.7 %) subjects. Median time taken to first negative RT-PCR test was 9 days (IQR, 6.7 - 13.25 days) and median duration of hospital stay of subjects was 14 (IQR, 10 – 18). Presence of hypertension, use of antibiotic azithromycin and use of angiotensin receptor blockers were found to be significant risk factors for persistent positivity. CONCLUSIONS Persistent RT-PCR positivity indicating prolonged viral shedding was seen in 12.7 % of patients. Hypertension and use of antibiotic azithromycin were independent risk factors of persistent RT-PCR positivity. The epidemiological burden of the finding needs to be assessed in a wider population with a larger sample size. KEY WORDS COVID-19, RT-PCR, Viral Persistence, Infectivity, Time to Negativity