Correlation Between Relative Nasopharyngeal Virus RNA Load and Lymphocyte Count Disease Severity in Patients with COVID-19

Abstract

The aim of this study was to analyze the correlation between dynamic changes in the nasopharyngeal viral load of patients infected with the new coronavirus causing pneumonia and lymphocyte count disease severity. Cases newly diagnosed with COVID-19 at the First Affiliated Hospital of Nanchang University from January 2020 to February 2020 were analyzed retrospectively. Quantitative real-time polymerase chain reaction was used to determine severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from throat swab sample DCT values; lymphocyte and lymphocyte subset counts, coagulation system factor levels, myocardial injury indexes, and laboratory biochemical indicators were compared between the mild group and the severe group. The correlation between the relative load of nasopharyngeal SARS-CoV-2 RNA and severe disease symptoms was analyzed. Of the 76 patients, 49 were male and 27 were female. The lymphocyte, CD4 + T lymphocyte, and CD8 + T lymphocyte counts all differed significantly between the two groups ( p < 0.001), as did differences in interleukin (IL)-2R, IL-6, and IL-8 levels ( p = 0.022, 0.026, and 0.012, respectively). Moreover, there were significant differences in prothrombin time, D-dimer, and fibrinogen levels between the mild group and the severe group ( p = 0.029, 0.006, and <0.001, respectively), and in lactate dehydrogenase and troponin ( p < 0.001 and p = 0.007, respectively). SARS-CoV-2 RNA load and lymphocyte count, CD4 + T lymphocyte count, and CD8 + T lymphocyte count were linearly negatively correlated ( p < 0.001). SARS-CoV-2 RNA load was positively correlated with IL-2R, prothrombin time, lactate dehydrogenase, and hypersensitive troponin T ( p = 0.002, p = 0.009, and p < 0.001, respectively). In addition, the time that it took for the nucleic acid test to turn negative was significantly shorter for patients in the mild group than for those in the severe group (Z = -6.713, p < 0.001).In conclusion, relative SARS-CoV-2 RNA load in the nasopharynx is closely related to COVID-19 severity. If the relative RNA load was higher, the lymphocyte count was lower, organ damage was greater, and the time it took for the nucleic acid test to turn negative was longer.

Clinical utility of cycle threshold values in the context of COVID-19

“…The PRISMA owchart of included studies is shown in Figure 1. Data from 18 studies were relevant for inclusion and are summarised in Tables 1 and 2. Twelve studies (63%) were conducted in China or Hong Kong, [10][11][12][13][14][15][16][17][18][19][20][21] three studies were performed in Europe [22][23][24] and three studies were carried out in the USA or Canada. [25][26][27] Nearly all studies reported data for specimens from the respiratory tract, although two studies analysed saliva, 21,22 one used stool and serum samples in addition to respiratory samples, 19 and one used both throat and anal swabs.…”

“…Six studies analysed SARS-CoV-2 Ct values at multiple time points for each patient, 10,11,[18][19][20][21] and seven studies determined Ct values at hospital admission or diagnosis. [12][13][14][15][16][17]22 Fourteen studies reported on the direct correlation of outcomes with Ct values. [10][11][12][13][14]16,17,20,[22][23][24][25][26][27] Three studies reported on the correlation of outcomes with viral load, determined using standard curves of Ct values versus RNA copy number, 15,19,21 and one study correlated outcomes with the inverse of Ct values, taken as a proxy for viral load.…”

“…Eleven studies (with numbers of PCR-positive patients ranging from 10 to 308) reported on the correlation between Ct value and disease severity, [10][11][12][13][14]16,17,20,23,25,26 ower Ct values from respiratory samples were associated with more severe disease in 7 (64%) of these ( Table 2). [11][12][13][14]16,17,23 Three studies (with numbers of PCR-positive patients ranging from 23 to 114) reported on the correlation between viral load determined via Ct values and disease severity 15,19,21 and one of these (which included 96 patients) reported that higher viral loads were signi cantly associated with more severe disease ( Table 2). 19 Of the 15 studies reporting on the correlation between Ct value or viral load determined via Ct value and disease severity, 11 were performed in hospitalised patients [10][11][12][13][14][15][16][17]19,21,23 and three included non-hospitalised patients.…”

“…[11][12][13][14]16,17,23 Three studies (with numbers of PCR-positive patients ranging from 23 to 114) reported on the correlation between viral load determined via Ct values and disease severity 15,19,21 and one of these (which included 96 patients) reported that higher viral loads were signi cantly associated with more severe disease ( Table 2). 19 Of the 15 studies reporting on the correlation between Ct value or viral load determined via Ct value and disease severity, 11 were performed in hospitalised patients [10][11][12][13][14][15][16][17]19,21,23 and three included non-hospitalised patients. 20,25,26 Of the eleven studies performed in hospitalised patients only, eight (73%) reported an association between Ct value and disease severity, [11][12][13][14]16,17,19,23 of which six showed statistical signi cance.…”

“…19 Of the 15 studies reporting on the correlation between Ct value or viral load determined via Ct value and disease severity, 11 were performed in hospitalised patients [10][11][12][13][14][15][16][17]19,21,23 and three included non-hospitalised patients. 20,25,26 Of the eleven studies performed in hospitalised patients only, eight (73%) reported an association between Ct value and disease severity, [11][12][13][14]16,17,19,23 of which six showed statistical signi cance. [12][13][14]17,19,23 None of three studies that included non-hospitalised patients reported that patients with severe disease had higher viral loads compared with those with mild disease.…”