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Several commercial assays for SARS-CoV-2 RT-PCR are available but few of them were assessed. We evaluate the Allplex 2019-nCoV (Seegene) assay using 41 nasopharyngeal samples. The rates of agreement were 92.7% and 100% with the GeneFinder COVID-19 plus (Elitech) and the diagnosis of the infectious disease specialist respectively. Four samples display a Ct < 22.0 for the E and RdRp genes while the N gene was not detected, suggesting a variability of the viral sequence. There was no cross-reactivity with other respiratory viruses. The Allplex 2019-nCoV appears as a reliable method, but additional evaluations using more samples are needed. RT-PCR assays should probably include at least 2 viral targets.

The correlation between real-time PCR (rt-PCR) cycle threshold (Ct) values for respiratory viruses and clinical outcomes remains unclear. This study evaluates the association between Ct values and clinical outcomes in patients tested via point-of-care testing upon emergency department (ED) admission. This is a retrospective analysis of adults admitted to a French university hospital ED for suspected lower respiratory tract infections (LRTI) requiring oxygen therapy between 2019 and 2020. Ct values were assessed for their association with symptom duration and clinical outcomes (hospital length of stay (LOS), Intensive Care Unit (ICU) admission, and 28-day mortality) using zero-inflated negative binomial regression (ZINB) and logistic regression models, adjusted for age, sex, co-infection, and symptom duration. A total of 410 patients were included, with 37 (9%) having co-infections with two pathogens and 2 (0.5%) with three pathogens. The most common pathogens were human rhinovirus/enterovirus (HRV/EV) (26.3%), influenza A (24.9%), and SARS-CoV-2 (21.9%). Median symptom duration was 3 days [IQR: 2-7]. Of the patients, 308 (75.1%) were hospitalized, 74 (18%) required ICU care, and the 28-day mortality rate was 11.7% (n = 48). Multivariable analysis showed that higher Ct values for SARS-CoV-2 were associated with reduced odds of hospitalization (OR = 0.75, p = 0.04) and shorter LOS (x0.96 days per Ct unit increase, p = 0.04). Similar trends for shorter LOS were observed for HRV/EV and RSV but did not reach statistical significance. Conversely, higher influenza A Ct values were linked to longer LOS (x1.05 days per Ct unit increase, p = 0.025). Higher Ct values for SARS-CoV-2 were also associated with lower 28-day mortality (OR = 0.87, p = 0.049). Ct values were not associated with ICU admission for any virus. This study supports the association of higher Ct values with shorter LOS and lower mortality for SARS-CoV-2. In contrast, higher Ct values for influenza A were linked to longer LOS. Ct values were not predictive of ICU admission, underscoring the complexity of the relationship between viral load and clinical outcomes.

Acute respiratory tract infections (ARTI), including the common cold, pharyngitis, sinusitis, otitis media, bronchiolitis and pneumonia are the most common diagnoses among patients seeking medical care in western countries, and account for most antibiotic prescriptions. While a confirmed and fast ARTI diagnosis is key for antibiotic prescribing, empiric antimicrobial treatment remains common, because viral symptoms are often clinically similar and difficult to distinguish from those caused by bacteria. As a result, inappropriate antibiotic prescriptions are high and in certain settings likely higher than the commonly estimated 30%. The QIAstat Respiratory Panel® assay (QIAstat RP) is a multiplexed in vitro diagnostics test for the rapid simultaneous detection of 21 pathogens directly from respiratory samples, including human mastadenovirus A-G, primate bocaparvovirus 1+2, human coronavirus (HKU1, NL63, OC43, 229E), human metapneumovirus A/B, rhinovirus/enterovirus, influenza A virus (no subtype, subtype H1, H1N1/2009, H3), influenza B virus, human respirovirus 1+3, human orthorubulavirus 2+4, human orthopneumovirus, Bordetella pertussis, Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella pneumophila. We describe the first multicenter study of 445 respiratory samples, collected through the 2016-2017 and 2018 respiratory seasons, with performance compared against BioFire FilmArray RP v1.7 and discrepancy testing by Seegene Allplex RP. The QIAstat RP demonstrated a positive percentage of agreement of 98.0% (95% CI: 96.0-99.1%) and a negative percentage agreement of 99.8% (95% CI: 99.6-99.9%). With use of this comprehensive and rapid test, improved patient outcomes and antimicrobial stewardship may potentially be achieved.

Background Multiplex polymerase chain reaction (mPCR) enables recovery of viruses from airways of patients with community-acquired pneumonia (CAP), although their clinical impact remains uncertain. Methods Among consecutive adult patients who had undergone a mPCR within 72 hours following their admission to one intensive care unit (ICU), we retrospectively included those with a final diagnosis of CAP. Four etiology groups were clustered: bacterial, viral, mixed (viral-bacterial) and no etiology. A composite criterion of complicated course (hospital death or mechanical ventilation > 7 days) was used. A subgroup analysis compared patients with bacterial and viral-bacterial CAP matched on the bacterial pathogens. Results Among 174 patients (132 men [76 %], age 63 [53–75] years, SAPSII 38 [27;55], median PSI score 106 [78;130]), bacterial, viral, mixed and no etiology groups gathered 46 (26 %), 53 (31 %), 45 (26 %) and 30 (17 %) patients, respectively. Virus-infected patients displayed a high creatine kinase serum level, a low platelet count, and a trend toward more frequent alveolar-interstitial infiltrates. A complicated course was more frequent in the mixed group (31/45, 69 %), as compared to bacterial (18/46, 39 %), viral (15/53, 28 %) and no etiology (12/30, 40 %) groups ( p  < 0.01). In multivariate analysis, the mixed (viral-bacterial) infection was independently associated with complicated course (reference: bacterial pneumonia; OR, 3.58; CI 95 %, 1.16–11; p  = 0.03). The subgroup analysis of bacteria-matched patients confirmed these findings. Conclusions Viral-bacterial coinfection during severe CAP in adults is associated with an impaired presentation and a complicated course.

Objectives To assess interobserver agreement and clinical significance of chest CT reporting in patients suspected of COVID-19. Methods From 16 to 24 March 2020, 241 consecutive patients addressed to hospital for COVID-19 suspicion had both chest CT and SARS-CoV-2 RT-PCR. Eight observers (2 thoracic and 2 general senior radiologists, 2 junior radiologists, and 2 emergency physicians) retrospectively categorized each CT into one out of 4 categories (evocative, compatible for COVID-19 pneumonia, not evocative, and normal). Observer agreement for categorization between all readers and pairs of readers with similar experience was evaluated with the Kappa coefficient. The results of a consensus categorization were correlated to RT-PCR. Results Observer agreement across the 4 categories was good between all readers (κ value 0.61 95% CI 0.60–0.63) and moderate to good between pairs of readers (0.54–0.75). It was very good (κ 0.81 95% CI 0.79–0.83), fair (κ 0.32 95% CI 0.29–0.34), moderate (κ 0.56 95% CI 0.54–0.58), and moderate (0.58 95% CI 0.56–0.61) for the categories evocative, compatible, not evocative, and normal, respectively. RT-PCR was positive in 97%, 50%, 31%, and 11% of cases in the respective categories. Observer agreement was lower ( p < 0.001) and RT-PCR positive cases less frequently categorized evocative in the presence of an underlying pulmonary disease ( p < 0.001). Conclusion Interobserver agreement for chest CT reporting using categorization of findings is good in patients suspected of COVID-19. Among patients considered for hospitalization in an epidemic context, CT categorized evocative is highly predictive of COVID-19, whereas the predictive value of CT decreases between the categories compatible and not evocative. Key Points • In patients suspected of COVID-19, interobserver agreement for chest CT reporting into categories is good, and very good to categorize CT “evocative.” • Chest CT can participate in estimating the likelihood of COVID-19 in patients presenting to hospital during the outbreak, CT categorized “evocative” being highly predictive of the disease whereas almost a third of patients with CT “not evocative” had a positive RT-PCR in our study. • Observer agreement is lower and CTs of positive RT-PCR cases less frequently “evocative” in presence of an underlying pulmonary disease.

France went through three deadly epidemic waves due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing major public health and socioeconomic issues. We proposed to study the course of the pandemic along 2020 from the outlook of two major Parisian hospitals earliest involved in the fight against COVID-19. Genome sequencing and phylogenetic analysis were performed on samples from patients and health care workers (HCWs) from Bichat (BCB) and Pitié-Salpêtrière (PSL) hospitals. A tree-based phylogenetic clustering method and epidemiological data were used to investigate suspected nosocomial transmission clusters. Clades 20A, 20B and 20C were prevalent during the spring wave and, following summer, clades 20A.EU2 and 20E.EU1 emerged and took over. Phylogenetic clustering identified 57 potential transmission clusters. Epidemiological connections between participants were found for 17 of these, with a higher proportion of HCWs. The joint presence of HCWs and patients suggest viral contaminations between these two groups. We provide an enhanced overview of SARS-CoV-2 phylogenetic changes over 2020 in the Paris area, one of the regions with highest incidence in France. Despite the low genetic diversity displayed by the SARS-CoV-2, we showed that phylogenetic analysis, along with comprehensive epidemiological data, helps to identify and investigate healthcare associated clusters.

Multiplex PCR tests have improved our understanding of respiratory viruses' epidemiology by allowing their wide range detection. We describe here the burden of these viruses in hospital settings over a five-year period. All respiratory samples from adult patients (>20 years old) tested by multiplex-PCR at the request of physicians, from May 1 2011 to April 30 2016, were included retrospectively. Viral findings are reported by season, patient age group, respiratory tract region (upper or lower) and type of clinical unit (intensive care unit, pneumology unit, lung transplantation unit and other medical units). In total, 7196 samples (4958 patients) were included; 29.2% tested positive, with viral co-infections detected in 1.6% of samples. Overall, two viral groups accounted for 60.2% of all viruses identified: picornaviruses (rhinovirus or enterovirus, 34.3%) and influenza (26.6%). Influenza viruses constituted the group most frequently identified in winter (34.4%), in the upper respiratory tract (32%) and in patients over the age of 70 years (36.4%). Picornavirus was the second most frequently identified viral group in these populations and in all other groups, including lower respiratory tract infections (41.3%) or patients in intensive care units (37.6%). This study, the largest to date in Europe, provides a broad picture of the distribution of viruses over seasons, age groups, types of clinical unit and respiratory tract regions in the hospital setting. It highlights the burden associated with the neglected picornavirus group. These data have important implications for the future development of vaccines and antiviral drugs.

An Emergency Use Authorization was issued in the United States and in Europe for a monoclonal antibody monotherapy to prevent severe COVID-19 in high-risk patients. This study aimed to assess the risk of emergence of mutations following treatment with a single monoclonal antibody. Bamlanivimab was administered at a single dose of 700 mg in a one-hour IV injection in a referral center for the management of COVID-19 in France. Patients were closely monitored clinically and virologically with nasopharyngeal RT-PCR and viral whole genome sequencing. Six patients were treated for a nosocomial SARS-CoV-2 infection, all males, with a median age of 65 years and multiple comorbidities. All patients were infected with a B.1.1.7 variant, which was the most frequent variant in France at the time, and no patients had E484 mutations at baseline. Bamlanivimab was infused in the six patients within 4 days of the COVID-19 diagnosis. Four patients had a favorable outcome, one died of complications unrelated to COVID-19 or bamlanivimab, and one kidney transplant patient treated with belatacept died from severe COVID-19 more than 40 days after bamlanivimab administration. Virologically, four patients cleared nasopharyngeal viral shedding within one month after infusion, while two presented prolonged viral excretion for more than 40 days. The emergence of E484K mutants was observed in five out of six patients, and the last patient presented a Q496R mutation potentially associated with resistance. CONCLUSIONS: These results show a high risk of emergence of resistance mutants in COVID-19 patients treated with monoclonal antibody monotherapy.

Although France was one of the most affected European countries by the COVID-19 pandemic in 2020, the dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) movement within France, but also involving France in Europe and in the world, remain only partially characterized in this timeframe. Here, we analyzed GISAID deposited sequences from January 1 to December 31, 2020 ( n = 638,706 sequences at the time of writing). To tackle the challenging number of sequences without the bias of analyzing a single subsample of sequences, we produced 100 subsamples of sequences and related phylogenetic trees from the whole dataset for different geographic scales (worldwide, European countries, and French administrative regions) and time periods (from January 1 to July 25, 2020, and from July 26 to December 31, 2020). We applied a maximum likelihood discrete trait phylogeographic method to date exchange events (i.e., a transition from one location to another one), to estimate the geographic spread of SARS-CoV-2 transmissions and lineages into, from and within France, Europe, and the world. The results unraveled two different patterns of exchange events between the first and second half of 2020. Throughout the year, Europe was systematically associated with most of the intercontinental exchanges. SARS-CoV-2 was mainly introduced into France from North America and Europe (mostly by Italy, Spain, the United Kingdom, Belgium, and Germany) during the first European epidemic wave. During the second wave, exchange events were limited to neighboring countries without strong intercontinental movement, but Russia widely exported the virus into Europe during the summer of 2020. France mostly exported B.1 and B.1.160 lineages, respectively, during the first and second European epidemic waves. At the level of French administrative regions, the Paris area was the main exporter during the first wave. But, for the second epidemic wave, it equally contributed to virus spread with Lyon area, the second most populated urban area after Paris in France. The main circulating lineages were similarly distributed among the French regions. To conclude, by enabling the inclusion of tens of thousands of viral sequences, this original phylodynamic method enabled us to robustly describe SARS-CoV-2 geographic spread through France, Europe, and worldwide in 2020.

Background Data on SARS-CoV-2 load in lower respiratory tract (LRT) are scarce. Our objectives were to describe the viral shedding and the viral load in LRT and to determine their association with mortality in critically ill COVID-19 patients. Methods We conducted a binational study merging prospectively collected data from two COVID-19 reference centers in France and Switzerland. First, we described the viral shedding duration (i.e., time to negativity) in LRT samples. Second, we analyzed viral load in LRT samples. Third, we assessed the association between viral presence in LRT and mortality using mixed-effect logistic models for clustered data adjusting for the time between symptoms’ onset and date of sampling. Results From March to May 2020, 267 LRT samples were performed in 90 patients from both centers. The median time to negativity was 29 (IQR 23; 34) days. Prolonged viral shedding was not associated with age, gender, cardiac comorbidities, diabetes, immunosuppression, corticosteroids use, or antiviral therapy. The LRT viral load tended to be higher in non-survivors. This difference was statistically significant after adjusting for the time interval between onset of symptoms and date of sampling (OR 3.78, 95% CI 1.13–12.64, p  = 0.03). Conclusions The viral shedding in LRT lasted almost 30 days in median in critically ill patients, and the viral load in the LRT was associated with the 6-week mortality.