Clinical and laboratory characteristics of symptomatic healthcare workers with suspected COVID-19: a prospective cohort study

Abstract

A comprehensive clinical and microbiological assessments of COVID-19 in front-line healthcare workers (HCWs) is needed. Between April 10th and May 28th, 2020, 319 HCWs with acute illness were reviewed. In addition to SARS-CoV-2 RT-PCR screening, a multiplex molecular panel was used for testing other respiratory pathogens. For SARS-CoV-2 positive HCWs, the normalized viral load, viral culture, and virus neutralization assays were performed weekly. For SARS-CoV-2 negative HCWs, SARS-CoV-2 serological testing was performed one month after inclusion. Among the 319 HCWs included, 67 (21.0%) were tested positive for SARS-CoV-2; 65/67 (97.0%) developed mild form of COVID-19. Other respiratory pathogens were found in 6/66 (9.1%) SARS-CoV-2 positive and 47/241 (19.5%) SARS-Cov-2 negative HCWs (p = 0.07). The proportion of HCWs with a viral load > 5.0 log10 cp/mL (Ct value < 25) was less than 15% at 8 days after symptom onset; 12% of HCWs were positive after 40 days (Ct > 37). More than 90% of cultivable virus had a viral load > 4.5 log10 cp/mL (Ct < 26) and were collected within 10 days after symptom onset. Among negative HCWs, 6/190 (3.2%) seroconverted. Our data suggest that the determination of viral load can be used for appreciating the infectiousness of infected HCWs. These data could be helpful for facilitating their return to work.

Persistence at one year of neutralizing antibodies after SARS-CoV-2 infection: Influence of initial severity and steroid use

“…Quantitative detection of SARS-CoV-2 antibodies targeting S1-RBD was determined by the Siemens SARS-CoV-2 IgG (sCOVG) assay on the Atellica IM platform (Siemens, Munich, Germany). Neutralising antibody quantification was performed according to the previously published protocol ( 2 ), based on a pseudotyped virus entry assay using a luciferase reporter gene. Pseudo-virus displaying full-length SARS-CoV-2 spike protein (derived from USA-WA1/2020 strain) was produced in HEK293T cells and used to infect HeLa-ACE2 cells.…”

Modeling remdesivir antiviral efficacy in COVID-19 hospitalized patients of the randomized, controlled, open-label DisCoVeRy trial

“…Similarly, we conducted the same analysis in patients with high or low viral load at admission, taking the cutoff of 3.5 log 10 copies/10 4 cells. This value represents the threshold level below which the virus cannot be cultured and is unlikely infectious (32) .…”

Rapid Antigen Tests for Voluntary Screen Testing

“…Figure 5 shows the estimated range of Ct values at a viral load of 100,000 Copies/mL from 42 identified standard curves. [12][13][14]20,22,23,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] The median Ct value at this viral load was 25.82 (interquartile range 23.03 to 29.27), with 46% of Ct values below 25, and 83% below 30. [12][13][14]20,22,23,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] The median Ct value at this viral load was 25.82 (interquartile range 23.03 to 29.27).…”

“…Figure 5. Ct Values at a Viral Load of 100,000 Copies/mL Estimated From 42 Standard Curves Box and Whisker plot of Ct values at a viral load of 100,000 Copies/mL from 42 identified PCR standard curves reported in 23 original articles [12][13][14]20,22,23,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. The median Ct value at this viral load was 25.82 (interquartile range 23.03 to 29.27).…”

“…Figure 6. Cumulative Distribution of Viral Loads at a Ct Value of 30 as Estimated From 42 Standard Curves Cumulative distribution curve derived from 42 PCR standard curves reported in 23 original articles [12][13][14]20,22,23,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. At a Ct value of 30, the median viral load was 5,400 copies/mL, and an estimated 83% of assays reported viral loads below 100,000 copies/mL at this threshold.…”