Rapid and reliable inactivation protocols for the diagnostics of emerging viruses: The example of SARS-CoV-2 and monkeypox virus.

The emergence and sustained transmission of novel pathogens are exerting an increasing demand on the diagnostics sector worldwide, as seen with the ongoing severe acute respiratory coronavirus 2 (SARS-CoV-2) pandemic and the more recent public health concern of monkeypox virus (MPXV) since May 2022. Appropriate and reliable viral inactivation measures are needed to ensure the safety of personnel handling these infectious samples. In the present study, seven commercialized diagnosis buffers, heat (56°C and 60°C), and sodium dodecyl sulfate detergent (2.0%, 1.0%, and 0.5% final concentrations) were tested against infectious SARS-CoV-2 and MPXV culture isolates on Vero cell culture. Cytopathic effects were observed up to 7 days postinoculation and viral load evolution was measured by semiquantitative polymerase chain reaction. The World Health Organization recommends an infectious titer reduction of at least 4 log10 . As such, the data show efficacious SARS-CoV-2 inactivation by all investigated methods, with >6.0 log10 reduction. MPXV inactivation was also validated with all investigated methods with 6.9 log10 reductions, although some commercial buffers required a longer incubation period to yield complete inactivation. These results are valuable for facilities, notably those without biosafety level-3 capabilities, that need to implement rapid and reliable protocols common against both SARS-CoV-2 and MPXV.

Performance of the QIAprep& Viral RNA UM Kit assay (Qiagen), an automatable method for RT-qPCR detection of SARS-CoV-2 without RNA extraction.

We evaluated the performance of the QIAprep& Viral RNA UM Kit (Qiagen) for SARS-CoV-2 detection. It displayed specificity and sensitivity required for SARS-CoV-2 RNA detection from swab transport media without RNA extraction. This method identifies accurately patients at risk of transmission while saving time and cost of extraction.

Evaluation of commercial Anti-SARS-CoV-2 neutralizing antibody assays in seropositive subjects.

The virus neutralization test (VNT) is the reference for the assessment of the functional ability of neutralizing antibodies (NAb) to block SARS-CoV-2 entry into cells. New competitive immunoassays measuring antibodies preventing interaction between the spike protein and its cellular receptor are proposed as surrogate VNT (sVNT). We tested three commercial sVNT (a qualitative immunochromatographic test and two quantitative immunoassays named YHLO and TECO) together with a conventional anti-spike IgG assay (bioMérieux) in comparison with an in-house plaque reduction neutralization test (PRNT50) using the original 19A strain and different variants of concern (VOC), on a panel of 306 sera from naturally-infected or vaccinated patients. The qualitative test was rapidly discarded because of poor sensitivity and specificity. Areas under the curve of YHLO and TECO assays were, respectively, 85.83 and 84.07 (p-value >0.05) using a positivity threshold of 20 for PRNT50, and 95.63 and 90.35 (p-value =0.02) using a threshold of 80. However, the performances of YHLO and bioMérieux were very close for both thresholds, demonstrating the absence of added value of sVNT compared to a conventional assay for the evaluation of the presence of NAb in seropositive subjects. In addition, the PRNT50 assay showed a reduction of NAb titers towards different VOC in comparison to the 19A strain that could not be appreciated by the commercial tests. Despite the good correlation between the anti-spike antibody titer and the titer of NAb by PRNT50, our results highlight the difficulty to distinguish true NAb among the anti-RBD antibodies with commercial user-friendly immunoassays.

Sars-Cov-2 Inactivation by a Panel of Commercialized Buffers and by Traditional Protocols (Heat or SDS) (preprint)

Following the rapid spread of COVID-19 across the globe, the intense response that was demanded of diagnostic centers and research laboratories prompted the use of numerous products and protocols for the management of SARS-CoV-2 specimens. In these settings, proper handling of such infectious specimen is necessary to ensure the safety of personnel and to reduce the risk of active transmission. Our aim was to evaluate the inactivation efficacy of different inactivating methods, notably from commercial lysis buffers available in diagnostic kits. Heat and sodium dodecyl sulfate detergent were also included in our investigations. A cell culture-based assay was used, and supported by molecular qRT-PCR detection, to show in vitro infectivity reduction after inactivation treatment. Overall, all the investigated methods were successful in inactivating SARS-CoV-2. Ten minutes of contact with the commercial buffers completely stopped in vitro SARS-CoV-2 infectivity. Fifteen minutes at 68°C and 30 minutes at 56°C as well as one hour with sodium dodecyl sulfate detergent at 2, 1, 0.5, and 0.1% yielded the same results. These findings demonstrate the reliability of these protocols with regards to biosafety. Inactivation by heat and sodium dodecyl sulfate detergent are rather simple and can be readily available methods for rendering an infectious SARS-CoV-2 specimen inactive, especially in settings where commercial buffers are not available.

Evaluation of Commercial Anti-SARS-CoV-2 Antibody Assays and Comparison of Standardized Titers in Vaccinated Health Care Workers.

With the availability of vaccines, commercial assays detecting anti-severe acute respiratory syndrome coronavirus-2 antibodies (Ab) evolved toward quantitative assays directed to the spike glycoprotein or its receptor binding domain (RBD). The main objective of the present study was to compare the Ab titers obtained with quantitative commercial binding Ab assays, after one dose (convalescent individuals) or two doses (naive individuals) of vaccine, in health care workers (HCW). Antibody titers were measured in 255 sera (from 150 HCW) with five quantitative immunoassays (Abbott RBD IgG II quant, bioMérieux RBD IgG, DiaSorin Trimeric spike IgG, Siemens Healthineers RBD IgG, Wantai RBD IgG). One qualitative total antibody anti-RBD detection assay (Wantai) was used to detect previous infection before vaccination. The results are presented in binding Ab units (BAU)/mL after application, when possible, of a conversion factor provided by the manufacturers and established from a World Health Organization internal standard. There was a 100% seroconversion with all assays evaluated after two doses of vaccine. With assays allowing BAU/mL correction, Ab titers were correlated (Pearson correlation coefficient, ρ, range: 0.85-0.94). The titer differences varied by a mean of 10.6% between Siemens and bioMérieux assays to 60.9% between Abbott and DiaSorin assays. These results underline the importance of BAU conversion for the comparison of Ab titer obtained with the different quantitative assays. However, significant differences persist, notably, between kits detecting Ab against the different antigens. A true standardization of the assays would be to include the International Standard in the calibration of each assay to express the results in IU/mL.

Baseline clinical features of COVID-19 patients, delay of hospital admission and clinical outcome: A complex relationship.

INTRODUCTION: Delay between symptom onset and access to care is essential to prevent clinical worsening for different infectious diseases. For COVID-19, this delay might be associated with the clinical prognosis, but also with the different characteristics of patients. The objective was to describe characteristics and symptoms of community-acquired (CA) COVID-19 patients at hospital admission according to the delay between symptom onset and hospital admission, and to identify determinants associated with delay of admission. METHODS: The present work was based on prospective NOSO-COR cohort data, and restricted to patients with laboratory confirmed CA SARS-CoV-2 infection admitted to Lyon hospitals between February 8 and June 30, 2020. Long delay of hospital admission was defined as ≥6 days between symptom onset and hospital admission. Determinants of the delay between symptom onset and hospital admission were identified by univariate and multiple logistic regression analysis. RESULTS: Data from 827 patients were analysed. Patients with a long delay between symptom onset and hospital admission were younger (p<0.01), had higher body mass index (p<0.01), and were more frequently admitted to intensive care unit (p<0.01). Their plasma levels of C-reactive protein were also significantly higher (p<0.01). The crude in-hospital fatality rate was lower in this group (13.3% versus 27.6%), p<0.01. Multiple analysis with correction for multiple testing showed that age ≥75 years was associated with a short delay between symptom onset and hospital admission (≤5 days) (aOR: 0.47 95% CI (0.34-0.66)) and CRP>100 mg/L at admission was associated with a long delay (aOR: 1.84 95% CI (1.32-2.55)). DISCUSSION: Delay between symptom onset and hospital admission is a major issue regarding prognosis of COVID-19 but can be related to multiple factors such as individual characteristics, organization of care and severe pathogenic processes. Age seems to play a key role in the delay of access to care and the disease prognosis.

Protocol for a prospective, observational, hospital-based multicentre study of nosocomial SARS-CoV-2 transmission: NOSO-COR Project.

INTRODUCTION: The newly identified SARS-CoV-2 can cause serious acute respiratory infections such as pneumonia. In France, mortality rate in the general population was approximately 10% and could reach higher levels at the hospital. In the current context of high incidence rates of SARS-CoV-2 in the community, a significant increase in the rate of nosocomial transmission is expected. The risk of nosocomial transmission could even be higher in low-income countries that have fragile healthcare systems. This protocol is intended to estimate the prevalence and incidence of suspected or confirmed cases of nosocomial SARS-CoV-2 infection, the clinical spectrum and the determinants (risk factors/protective) at participating hospitals. METHODS AND ANALYSIS: This will be an international multicentre prospective, observational, hospital-based study in adults and children. It will include volunteer patients and healthcare professionals in France and hospitals affiliated with the GABRIEL network. Demographic and clinical data will be collected using case report forms designed especially for the purpose of the project. A nasopharyngeal swab will be collected and tested for SARS-CoV-2 by reverse-transcriptase PCR. Characteristics of the study participants, the proportion of confirmed nosocomial SARS-CoV-2 infections relative to all patients with syndromes suggestive of SARS-CoV-2 infection, will be analysed. Appropriate multivariate modelling will be used to identify the determinants associated with nosocomial onset. ETHICS AND DISSEMINATION: This study was approved by the clinical research and committee of all participating countries. The findings will be submitted to peer-reviewed journal for publication and shared with national health authorities. TRIAL REGISTRATION NUMBER: NCT04290780.

Factors associated with admission to intensive care units in COVID-19 patients in Lyon-France.

INTRODUCTION: A new respiratory virus, SARS-CoV-2, has emerged and spread worldwide since late 2019. This study aims at analysing clinical presentation on admission and the determinants associated with admission in intensive care units (ICUs) in hospitalized COVID-19 patients. PATIENTS AND METHODS: In this prospective hospital-based study, socio-demographic, clinical and biological characteristics, on admission, of adult COVID-19 hospitalized patients presenting from the community for their first admission were prospectively collected and analysed. Characteristics of patients hospitalized in medical ward to those admitted in ICU were compared using Mann-Whitney and Chi-square or Fisher exact test when appropriate. Univariate logistic regression was first used to identify variables on admission that were associated with the outcome i.e. admission to an ICU versus total hospital stay in a medical ward. Forward selection was then applied beginning with sex, age and temperature in the multivariable logistic regression model. RESULTS: Of the 412 patients included, 325 were discharged and 87 died in hospital. Multivariable regression showed increasing odds of ICU hospitalization with temperature (OR, 1.56 [95% CI, 1.06-2.28] per degree Celsius increase), oxygen saturation <90% (OR, 12.45 [95% CI, 5.27-29.4]), abnormal lung auscultation on admission (OR, 3.58 [95% CI, 1.58-8.11]), elevated level of CRP (OR, 2.7 [95% CI, 1.29-5.66for CRP>100mg/L vs CRP<10mg/L). and monocytopenia (OR, 3.28 [95% CI, 1.4-7.68]) were also associated with increasing odds of ICU hospitalization. Older patients were less likely to be hospitalized in ICU (OR, 0.17 [95%CI, 0.05-0.51]. CONCLUSIONS: Age and delay between onset of symptoms and hospital admission were associated with the risk of hospitalisation in ICU. Age being a fixed variable, interventions that shorten this delay would improve the prognosis of Covid-19 patients.

Comparison of eight commercial, high-throughput, automated or ELISA assays detecting SARS-CoV-2 IgG or total antibody.

BACKGROUND: Many commercial assays, of different designs, detecting SARS-CoV-2-specific antibodies exist but with little experience with them. OBJECTIVES: The aim of this study was to compare the performance of assays detecting IgG or total antibodies to N or S antigens, validated for routine use in France, with samples from subjects with more or less severe SARS-CoV-2 infection. METHODS: Eight assays were used: Abbott Architect, DiaSorin Liaison®, bioMérieux Vidas®, Roche Elecsys Cobas®, Siemens Atellica®, BioRad Platelia ELISA, Epitope Diagnostics ELISA, and Wantai ELISA. The tested population included 86 samples from 40 hospitalized subjects and 28 outpatients at different time from symptom onset. RESULTS: The positivity rate varied depending on the assay but was greater for all assays in hospitalized than non-hospitalized patients. Despite a good correlation between the assays, discrepancies occurred, without a systematic origin, even for samples taken more than 20 days after symptom onset. These discrepancies were linked to low antibody levels in pauci-symptomatic patients. CONCLUSION: Whichever assay is chosen, a false negative result may need to be ruled out with another test in a risk situation.

Performance Assessment of SARS-CoV-2 PCR Assays Developed by WHO Referral Laboratories.

A reliable diagnostic assay is crucial to early detect new COVID-19 cases and limit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Since the onset of the COVID-19 pandemic, the World Health Organization has published several diagnostic molecular approaches developed by referral laboratories, including Charité (Germany), HKU (Hong Kong), China CDC (China), US CDC (United States), and Institut Pasteur, Paris (France). We aimed to compare the sensitivity and specificity of these different RT-PCR assays using SARS-CoV-2 cell culture supernatants and clinical respiratory samples. Overall, the different RT-PCR assays performed well for SARS-CoV-2 detection and were all specific except the N Charité (Germany), and N2 US CDC (United States) assays. RdRp Institut Pasteur (IP2, IP4), N China CDC, and N1 US CDC were found to be the most sensitive assays. The data presented herein are of prime importance to facilitate the equipment choice of diagnostic laboratories, as well as for the development of marketed tests.