Droplets adhesion to surgical masks during standard oral surgery.

The most common routes of transmission of coronavirus disease 2019 are droplet and contact infections. During dental treatment, many instruments are used that generate droplets of saliva and blood. Several droplets are generated during extraction of an impacted third molar (M3). Surgical masks are often used during tooth extraction; however, the surface structure of surgical masks against droplets is not fully understood. Therefore, we analyzed the droplets adhered to surgical masks during impacted M3 extraction using electron microscopy. A surgical mask used during impacted M3 extraction was studied. The collected surgical mask was divided into three layers and observed using electron microscopy. The outer and inner layers had a similar mesh-like structure, while the middle layer had a denser three-dimensional structure. Droplets ranging from 20-100 µm in size generated during the extraction adhered to the fibers of the outer layer of the mask. Fewer droplets adhered in the middle layer than those in the outer layer. No droplets reached the inner layer. In conclusion, it is suggested that a surgical mask can prevent droplet infection when performing impacted M3 extraction. This study is expected to contribute to the study of infection control strategies during dental treatment in the future.

Evaluation of minocycline combined with favipiravir therapy in coronavirus disease 2019 patients: A case-series study.

The aim of this study was to investigate the efficacy and safety of minocycline (MIN) and favipiravir combination therapy in patients with coronavirus disease 2019 (COVID-19) admitted to our hospital in Fukui Prefecture, Japan, in March and April of 2020. In this retrospective study, a favipiravir monotherapy group (Control group, n = 9) was compared with a combined favipiravir plus MIN therapy group (MIN group, n = 12). No severe cases were present. The primary comparative endpoints evaluated were duration of fever, duration of hospitalization, duration from treatment initiation to severe acute respiratory syndrome coronavirus 2 polymerase chain reaction (PCR)-negative results, and changes in cytokine and chemokine production. Median duration from start of treatment to negative PCR test was significantly shorter in the MIN group than in the Control group. Mean rates of cytokine and chemokine reduction were significantly greater for interleukin-6 and interleukin-8 in the MIN group. No difference in adverse event rates were seen between groups, and only minor adverse events were encountered. MIN has been reported to have not only broad antibacterial activity, but also antiviral and anti-inflammatory activity. The present results support the efficacy and safety of MIN plus favipiravir therapy for the treatment of COVID-19.

SARS-CoV-2 RNAemia with a higher nasopharyngeal viral load is strongly associated with disease severity and mortality in patients with COVID-19.

This study aimed to determine the frequency of SARS-CoV-2 RNA in serum and its association with the clinical severity of COVID-19. This retrospective cohort study performed at Toyama University Hospital included consecutive patients with confirmed COVID-19. The prevalence of SARS-CoV-2 RNAemia and the strength of its association with clinical severity variables were examined. Fifty-six patients were included in this study. RNAemia was detected in 19.6% (11/56) patients on admission, and subsequently in 1.0% (1/25), 50.0% (6/12), and 100.0% (4/4) moderate, severe, and critically ill patients, respectively. Patients with RNAemia required more frequent oxygen supplementation (90.0% vs. 13.3%), ICU admission (81.8% vs. 6.7%), and invasive mechanical ventilation (27.3% vs. 0.0%). Among patients with RNAemia, the median viral loads of nasopharyngeal (NP) swabs that were collected around the same time as the serum sample were significantly higher in critically ill (5.4 log10 copies/µl; interquartile range [IQR]: 4.2-6.3) than in moderate-severe cases (2.6 log10 copies/µl; [IQR: 1.1-4.5]; p = 0.030) and were significantly higher in nonsurvivors (6.2 log10 copies/µl [IQR: 6.0-6.5]) than in survivors (3.9 log10 copies/µl [IQR: 1.6-4.6]; p = 0.045). This study demonstrated a relatively high proportion of SARS-CoV-2 RNAemia and an association between RNAemia and clinical severity. Moreover, among the patients with RNAemia, the viral loads of NP swabs were correlated with disease severity and mortality, suggesting the potential utility of combining serum testing with NP tests as a prognostic indicator for COVID-19, with higher quality than each separate test.

Delayed neutralizing antibody response in the acute phase correlates with severe progression of COVID-19.

Adaptive immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dynamics remain largely unknown. The neutralizing antibody (NAb) levels in patients with coronavirus disease 2019 (COVID-19) are helpful for understanding the pathology. Using SARS-CoV-2 pseudotyped virus, serum sample neutralization values in symptomatic COVID-19 patients were measured using the chemiluminescence reduction neutralization test (CRNT). At least two sequential serum samples collected during hospitalization were analyzed to assess NAbs neutralizing activity dynamics at different time points. Of the 11 patients, four (36.4%), six (54.5%), and one (9.1%) had moderate, severe, and critical disease, respectively. Fifty percent neutralization (N50%-CRNT) was observed upon admission in 90.9% (10/11); all patients acquired neutralizing activity 2-12 days after onset. In patients with moderate disease, neutralization was observed at earliest within two days after symptom onset. In patients with severe-to-critical disease, neutralization activity increased, plateauing 9-16 days after onset. Neutralization activity on admission was significantly higher in patients with moderate disease than in patients with severe-to-critical disease (relative % of infectivity, 6.4% vs. 41.1%; P = .011). Neutralization activity on admission inversely correlated with disease severity. The rapid NAb response may play a crucial role in preventing the progression of COVID-19.

Investigation of nasopharyngeal viral load at discharge in patients with COVID-19.

This study aimed to assess the nasopharyngeal viral load at discharge or time of discontinued isolation in coronavirus 2019 (COVID-19) patients admitted to our hospital and discharged under the current symptom-based criteria in Japan. Patients diagnosed with COVID-19 by reverse transcription polymerase chain reaction and hospitalized at Toyama University Hospital were included in the analysis. Nasopharyngeal viral load was measured when symptom-based criteria for discharge or end of isolation in the accommodations were met, and examined the relationship between viral load and days after onset or age. From the perspective of virus isolation limit, the amount of infectious viral load was defined at 50 copies/µL by nasopharyngeal sample. Thirty-three patients with laboratory-confirmed COVID-19 were included in the analysis, after excluding critical and fatal cases. Mean nasopharyngeal viral load at discharge or end of isolation was 1.90 log-copies/µL, and 64% of patients were discharged with over 50 copies/µL. No correlation was apparent between age and viral load at discharge, and viral load remained relatively high at discharge or end of isolation in all age groups. Although attempts at infectious virus isolation are necessary, infection control precautions even after discharge or discontinued isolation in accommodations may be needed, as the date of onset mostly depended on self-reporting by patients.

Prolonged viral clearance of severe acute respiratory syndrome coronavirus 2 in the older aged population.

INTRODUCTION: The detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) is the standard method for the diagnosis of coronavirus disease 2019 (COVID-19). This PCR test can be positive even in patients who have recovered from the disease, and the duration for achieving viral clearance has not been clarified yet. METHODS: This study was conducted between April 3, 2020, and June 17, 2020, at the Toyama University Hospital and the Toyama Rehabilitation Home. We collected the data of patients with COVID-19, analyzing the duration until twice-consecutive negative qRT-PCR test. RESULTS: A total of 42 patients were enrolled. The median duration of the twice-consecutive negative qRT-PCR test was 29.0 d (interquartile range: 25.75-35.25). The longest duration of viral shedding was 73 d. The duration of viral clearance was significantly longer in the older (>65 years) group than in the younger group (34.5 d vs. 25.0 d, P < 0.0001). CONCLUSION: This study demonstrated that viral clearance tends to be sustained in the older adults.

A case of COVID-19 diagnosed with favipiravir-induced drug fever based on a positive drug-induced lymphocyte stimulation test.

As of October 2020, there is still no specific drug to treat COVID-19 as it rages worldwide. Favipiravir, indicated for the treatment of new and re-emerging influenza infections, has been suggested to be effective against SARS-CoV-2, although this is not yet fully validated. We administered favipiravir to a 64-year-old female patient with COVID-19. Her symptoms resolved quickly after the start of treatment, with reduction of SARS-CoV-2 viral load, but she developed a fever again on day 12. Since the fever was relieved by discontinuation of favipiravir, and based on positive results with a drug-induced lymphocyte stimulation test, we diagnosed her with favipiravir-induced drug fever. A decrease in the serum concentration of favipiravir was observed along with resolution of the fever. The present case suggests that drug fever should be considered in the differential diagnosis of relapsing fever episodes in COVID-19 patients receiving favipiravir.

Evaluation of SARS-CoV-2 neutralizing antibodies using a vesicular stomatitis virus possessing SARS-CoV-2 spike protein.

BACKGROUND: SARS-CoV-2 is a novel coronavirus that emerged in 2019 and is now classified in the genus Coronavirus with closely related SARS-CoV. SARS-CoV-2 is highly pathogenic in humans and is classified as a biosafety level (BSL)-3 pathogen, which makes manipulating it relatively difficult due to its infectious nature. METHODS: To circumvent the need for BSL-3 laboratories, an alternative assay was developed that avoids live virus and instead uses a recombinant VSV expressing luciferase and possesses the full length or truncated spike proteins of SARS-CoV-2. Furthermore, to measure SARS-CoV-2 neutralizing antibodies under BSL2 conditions, a chemiluminescence reduction neutralization test (CRNT) for SARS-CoV-2 was developed. The neutralization values of the serum samples collected from hospitalized patients with COVID-19 or SARS-CoV-2 PCR-negative donors against the pseudotyped virus infection evaluated by the CRNT were compared with antibody titers determined from an enzyme-linked immunosorbent assay (ELISA) or an immunofluorescence assay (IFA). RESULTS: The CRNT, which used whole blood collected from hospitalized patients with COVID-19, was also examined. As a result, the inhibition of pseudotyped virus infection was specifically observed in both serum and whole blood and was also correlated with the results of the IFA. CONCLUSIONS: In conclusion, the CRNT for COVID-19 is a convenient assay system that can be performed in a BSL-2 laboratory with high specificity and sensitivity for evaluating the occurrence of neutralizing antibodies against SARS-CoV-2.

Transmissibility of COVID-19 depends on the viral load around onset in adult and symptomatic patients.

OBJECTIVE: To investigate the relationship between viral load and secondary transmission in novel coronavirus disease 2019 (COVID-19). METHODS: Epidemiological and clinical data were obtained from immunocompetent laboratory-confirmed patients with COVID-19 who were admitted to and/or from whom viral loads were measured at Toyama University Hospital. Using a case-control approach, index patients who transmitted the disease to at least one other patient were analysed as "cases" (index patients) compared with patients who were not the cause of secondary transmission (non-index patients, analysed as "controls"). The viral load time courses were assessed between the index and non-index symptomatic patients using non-linear regression employing a standard one-phase decay model. RESULTS: In total, 28 patients were included in the analysis. Median viral load at the initial sample collection was significantly higher in symptomatic than in asymptomatic patients and in adults than in children. Among symptomatic patients (n = 18), non-linear regression models showed that the estimated viral load at onset was higher in the index than in the non-index patients (median [95% confidence interval]: 6.6 [5.2-8.2] vs. 3.1 [1.5-4.8] log copies/µL, respectively). In adult (symptomatic and asymptomatic) patients (n = 21), median viral load at the initial sample collection was significantly higher in the index than in the non-index patients (p = 0.015, 3.3 vs. 1.8 log copies/µL, respectively). CONCLUSIONS: High nasopharyngeal viral loads around onset may contribute to secondary transmission of COVID-19. Viral load may help provide a better understanding of why transmission is observed in some instances, but not in others, especially among household contacts.

Monitoring of viral load by RT-PCR caused decision making to continue ECMO therapy for a patient with COVID-19.

Most patients with coronavirus disease 2019 (COVID-19) have just only mild symptoms, but about 5% are very severe. Although extracorporeal membranous oxygenation (ECMO) is sometimes used in critically patients with COVID-19, ECMO is only an adjunct, not the main treatment. If the patient's condition deteriorates and it is determined to be irreversible, it is necessary to decide to stop ECMO. A 54-year-old man was admitted on day 6 of onset with a chief complaint of high fever and cough. Computed tomography (CT) showed a ground glass opacity in both lungs, and reverse transcription-polymerase chain reaction (RT-PCR) diagnosed COVID-19. He was admitted to the hospital and started to receive oxygen and favipiravir. After that, his respiratory condition deteriorated, and he was intubated and ventilated on day 9 of onset, and ECMO was introduced on day 12. Two days after the introduction of ECMO, C-reactive protein (CRP) increased, chest X-p showed no improvement in pneumonia, and PaO2/FiO2 decreased again. As D-dimer rose and found a blood clot in the ECMO circuit, we had to decide whether to replace the circuit and continue with ECMO or stop ECMO. At this time, the viral load by RT-PCR was drastically reduced to about 1/1750. We decided to continue ECMO therapy and replaced the circuit. The patient's respiratory status subsequently improved and ECMO was stopped on day 21 of onset. In conclusion, viral load measurement by RT-PCR may be one of the indicators for promoting the treatment of severe COVID-19 patients.