Dynamic profile of RT-PCR findings from 301 COVID-19 patients in Wuhan, China: A descriptive study

Abstract

Background: With the spread of Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection, its effect on society is amplified. We aimed to describe the viral detection results across different timepoints throughout the disease course.

Methods: A retrospective study of 301 confirmed COVID-19 patients hospitalized at Tongji Hospital in Wuhan, China, were included. Demographic characteristics of the patients were collected. Upper respiratory specimens (throat and/or nasal swabs) were obtained and analyzed by real-time RT-PCR for SARS-CoV-2 infection. Period of viral infection and the contagious stage were analyzed.

Results: Of 301 hospitalized COVID-19 patients, the median age was 58 years and 51.2 % were male. The median period between symptoms presence and positive SARS-CoV-2 RT-PCR results was 16 days (IQR, 10-23, N = 301). The median period between symptoms presence and an effective negative SARS-CoV-2 RT-PCR result was 20 days (IQR, 17-24; N = 216). Infected patient ≥65 years old stayed contagious longer (22 days vs 19 days, p = 0.015). Although two consecutive negative results were confirmed in 70 patients, 30 % of them had positive viral test results for the third time. Using specimens from nasal swabs to run the RT-PCR test showed a higher positive rate than using specimens from throat swabs.

Conclusions: This large-scale investigation with 1113 RT-PCR test results from 301 COVID-19 patients showed that the average contagious period of SARS-CoV-2 infected patients was 20 days. Longer observation period and more than 2 series of negative viral test are necessary for patients ≥65 years.

Keywords: COVID-19; Dynamic profile; RT-PCR; SARS-CoV-2.

Fig. 1

Dynamic Profile of SARS-CoV-2 Infection. (A) Dynamic Profile of SARS-CoV-2 Detected by RT-PCR from 301 COVID-19 Patients (N = 1113). Numbers of the positive (red bar) and negative (blue bar) results of SARS-CoV-2 RT-PCR were sum on every day based on the days after the onset. (B) Positive rate of SARS-CoV-2 Detected by RT-PCR from 301 COVID-19 Patients (N = 1113). Percentage of positive results of SARS-CoV-2 RT-PCR were calculated on every day based on the days after the onset.

Fig. 2

Impact of Age and Gender on Dynamic Profile of SARS-CoV-2. (A) The median time of SARS-CoV-2 infection (positive, red triangle) and SARS-CoV-2 conversion (negative, purple square) grouped by age. (B) The median time of SARS-CoV-2 infection (positive, red triangle) and SARS-CoV-2 conversion (negative, purple square) grouped by gender. The I bars indicate the 25th and 75th percentiles. P < .05 was considered statistically significant.

Fig. 3

Estimation of false negative result of SARS-CoV-2 RT-PCR assay and comparison of throat swabs and nasal swabs. (A). Three sequential SARS-CoV-2 RT-PCR assays. Red square indicates positive results for the third time and blue square indicate negative results. (B) Comparison of SARS-CoV-2 RT-PCR assay from paired specimens obtained by throat swabs and nasal swabs.