scholarly journals Variation in SARS-CoV-2 bioaerosol production in exhaled breath

2021 ◽  
Author(s):  
Renu Verma ◽  
Eugene Kim ◽  
Nicholas Degner ◽  
Katharine S. Walter ◽  
Upinder Singh ◽  
...  
Keyword(s):  
Viral Load ◽  
Nasal Swab ◽  
Face Mask ◽  
Exhaled Breath ◽  
Substantial Variation ◽  
Minute Period

Using face mask bioaerosol sampling, we found substantial variation between individuals in SARS-CoV-2 copies exhaled over a 15-minute period, which moderately correlated with nasal swab viral load. Talking was associated with a median of 2 log10 greater exhaled viral copies. Exposure varies substantially between individuals but may be risk stratified by nasal swab viral load and whether the exposure involved conversation.

scholarly journals Variation in SARS-CoV-2 bioaerosol production in exhaled breath

2021 ◽  
Author(s):  
Renu Verma ◽  
Eugene Kim ◽  
Nicholas Degner ◽  
Katharine S Walter ◽  
Upinder Singh ◽  
...  
Keyword(s):  
Viral Load ◽  
Sampling Method ◽  
Nasal Swab ◽  
Exhaled Breath ◽  
Substantial Variation ◽  
Non Invasive ◽  
Minute Period

Abstract We developed a simple, non-invasive mask sampling method to quantify and sequence SARS-CoV-2 from exhaled breath. We found substantial variation between individuals in SARS-CoV-2 copies exhaled over a 15-minute period, which moderately correlated with nasal swab viral load. Talking was associated with a median of 2 log10 greater exhaled viral copies. Exposure varies substantially between individuals but may be risk stratified by nasal swab viral load and whether the exposure involved conversation.

scholarly journals Prolonged Detection of SARS CoV2 RNA in Extracellular Vesicles in Nasal Swab RT-PCR Negative Patients

2021 ◽  
Author(s):  
P Debishree Subudhi ◽  
Sheetalnath Rooge ◽  
Swati Thangriyal ◽  
Reshu Aggarwal ◽  
Ekta Gupta ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Viral Load ◽  
Liver Disease ◽  
Chronic Liver Disease ◽  
Extracellular Vesicles ◽  
Nasal Swab ◽  
High Viral Load ◽  
Chronic Liver ◽  
Rt Pcr ◽  
Route Of Transmission

Background: There is a prolonged RT PCR positivity seen in COVID-19 infected patients up to 2 to 3 months. It is assumed that this virus is usually non-infective but there are hardly any study on the reactivation of this virus within the respiratory tract. We aim to investigate the presence of viral particles inside Extracellular vesicles (EV) and its role in underlying liver disease patients. Methods: SARS CoV2 nasal and throat swab RT-PCR positive n=78 {n=24(66.6%) chronic liver disease (CLD); n=52 (81.3%) non liver disease} n=5 RT PCR negative subjects (HC) were studied. SARS CoV2 patients were also followed up for day (d) 7, 14 and 28. Nasal swab [collected in viral transport media (VTM)] and plasma samples were investigated at each time point. Extracellular vesicles were isolated using differential ultracentrifugation. SARS CoV2 RNA was measured using qRT-PCR by Altona Real Star kit. Cellular origin of EV was confirmed using epithelial cells (Epcam+ CK19+ CDh1+), endothelial cells (CD31+CD45-), and hepatocytes (ASGPR+) surface markers by Flow cytometry. Results: The COVID19 patients {Mean age 54±23 years; 41 males} were having severity between moderate to severe. In patients with cirrhosis, the most common aetiology of liver disease was alcohol (MELD 22±8). In baseline RT-PCR positive patients, SARS-CoV2 RNA inside the EV was present in 64/74 (82%) patients with comparable viral load between VTM and EV (mean 1/CT 0.033±0.005 vs. 1/CT 0.029±0.014, p=ns). On follow-up at day 7, of the 24 patients negative for COVID19, 10 (41%) had persistence of virus in the EV (1/CT 0.028±0.004) and on day 14, 14 of 40 (35%) negative RT-PCR had EVs with SARS CoV2 RNA (1/CT 0.028±0.06). The mean viral load decreased at day7 and day14 in nasal swab from baseline (p=0.001) but not in EV. SARS-CoV2 RNA otherwise undetectable in plasma, was found to be positive in EV in 12.5% of COVID19 positive patients. Interestingly, significantly prolonged and high viral load was found in EV at day 14 in CLD COVID19 patients compared to COVID19 alone (p=0.002). The high cellular injury was seen in CLD COVID19 infected patients with significant high levels of EV associated with endothelial cells and hepatocytes than COVID19 alone (p=0.004; 0.001). Conclusion: Identification of SARS-CoV2 RNA in EV, in RT-PCR negative patients indicates persistence of infection for and likely recurrence of the infection. It is suggestive of another route of transmission as EV harbour SARS CoV2 RNA. EV associated RNA may determine the ongoing inflammation and clinical course of subjects with undetectable SARS-CoV2 virus and this may also have relevance in management of chronic liver disease patients.

scholarly journals Viral Load of SARS-CoV-2 in Respiratory Aerosols Emitted by COVID-19 Patients while Breathing, Talking, and Singing

2021 ◽  
Author(s):  
Kristen K. Coleman ◽  
Douglas Jie Wen Tay ◽  
Kai Sen Tan ◽  
Sean Wei Xiang Ong ◽  
Than The Son ◽  
...  
Keyword(s):  
Viral Load ◽  
Significant Role ◽  
N Gene ◽  
Exhaled Breath ◽  
Indoor Environments ◽  
Future Studies ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Gene Copies ◽  
Study Participants

Background: Multiple SARS-CoV-2 superspreading events suggest that aerosols play an important role in driving the COVID-19 pandemic. However, the detailed roles of coarse (>5μm) and fine (≤5μm) respiratory aerosols produced when breathing, talking, and singing are not well-understood. Methods: Using a G-II exhaled breath collector, we measured viral RNA in coarse and fine respiratory aerosols emitted by COVID-19 patients during 30 minutes of breathing, 15 minutes of talking, and 15 minutes of singing. Results: Among the 22 study participants, 13 (59%) emitted detectable levels of SARS-CoV-2 RNA in respiratory aerosols, including 3 asymptomatic patients and 1 presymptomatic patient. Viral loads ranged from 63 - 5,821 N gene copies per expiratory activity. Patients earlier in illness were more likely to emit detectable RNA, and loads differed significantly between breathing, talking, and singing. The largest proportion of SARS-CoV-2 RNA copies was emitted by singing (53%), followed by talking (41%) and breathing (6%). Overall, fine aerosols constituted 85% of the viral load detected in our study. Virus cultures were negative. Conclusions: Fine aerosols produced by talking and singing contain more SARS-CoV-2 copies than coarse aerosols and may play a significant role in the transmission of SARS-CoV-2. Exposure to fine aerosols should be mitigated, especially in indoor environments where airborne transmission of SARS-CoV-2 is likely to occur. Isolating viable SARS-CoV-2 from respiratory aerosol samples remains challenging, and whether this can be more easily accomplished for emerging SARS-CoV-2 variants is an important enquiry for future studies.

scholarly journals Effect of hydroxychloroquine on SARS-CoV-2 viral load in patients with COVID-19

2020 ◽  
Author(s):  
Klinger Soares Faíco-Filho ◽  
Danielle Dias Conte ◽  
Luciano Kleber de Souza Luna ◽  
Joseane Mayara Almeida Carvalho ◽  
Ana Helena Sitta Perosa ◽  
...  
Keyword(s):  
Viral Load ◽  
Prospective Study ◽  
Nasal Swab ◽  
Effective Drug ◽  
Medical Decision ◽  
Control Group ◽  
Sample Collection ◽  
Significant Difference

ABSTRACTBackgroundSome studies have shown that hydroxychloroquine (HCQ) is an effective drug in reducing the in vitro replication of SARS-CoV-2. However, the in vivo effect of HCQ still unclear. This study aims to evaluate viral load clearance in patients with COVID-19 who underwent HCQ treatment in comparison with a control group that did not receive the drug.MethodsThis prospective study comprised consecutive viral load measurements in patients with COVID-19 hospitalized with a moderate illness. Patients received 400 mg of HCQ every 12 hours for 10 days according to the medical decision. Nasal swab samples were collected at the 1st, 7th, and 14th days of the admission.Results155 samples were collected from 66 patients with COVID-19 (60% female), with a median age of 58 years. The viral load between studied groups, assumed as a semiquantitative measure of cycle threshold (Ct) values, presented no significant difference within the three consecutive measures (ΔCt) (p>0.05). We also analyzed the ΔCt viral load at different intervals of sample collection (Δt <7; 7-12 and >12 days) without significant differences at any ΔCt (p>0.05).ConclusionIn this study, we did not observe any change in viral load in vivo with the use of HCQ.SummaryWe evaluate viral load clearance in patients with COVID-19 who took hydroxychloroquine (HCQ) for treatment and those who not. Prospective viral load measurements have shown any change in viral load in vivo with the use of HCQ.

scholarly journals Quantitative SARS-CoV-2 viral-load curves in paired saliva and nasal swabs inform appropriate respiratory sampling site and analytical test sensitivity required for earliest viral detection

2021 ◽  
Author(s):  
Emily S. Savela ◽  
Alexander Winnett ◽  
Anna E. Romano ◽  
Michael K. Porter ◽  
Natasha Shelby ◽  
...  
Keyword(s):  
Viral Load ◽  
Los Angeles ◽  
Nasal Swab ◽  
Sampling Site ◽  
High Sensitivity ◽  
Analytical Sensitivity ◽  
Viral Loads ◽  
Analytical Test ◽  
Nasal Swabs ◽  
High Analytical Sensitivity

Early detection of SARS-CoV-2 infection is critical to reduce asymptomatic and pre-symptomatic transmission, curb the spread of variants, and maximize treatment efficacy. Low-analytical-sensitivity nasal-swab testing is commonly used for surveillance and symptomatic testing, but the ability of these tests to detect the earliest stages of infection has not been established. In this study, conducted between September 2020 and June 2021 in the greater Los Angeles County, California area, initially-SARS-CoV-2-negative household contacts of individuals diagnosed with COVID-19 prospectively self-collected paired anterior-nares nasal-swab and saliva samples twice daily for viral-load quantification by high-sensitivity RT-qPCR and digital-RT-PCR assays. We captured viral-load profiles from the incidence of infection for seven individuals and compared diagnostic sensitivities between respiratory sites. Among unvaccinated persons, testing saliva with a high-analytical-sensitivity assay detected infection up to 4.5 days before viral loads in nasal swabs reached concentrations detectable by low-analytical-sensitivity nasal-swab tests. For most participants, nasal swabs reached higher peak viral loads than saliva, but were undetectable or at lower loads during the first few days of infection. High-analytical-sensitivity saliva testing was most reliable for earliest detection. Our study illustrates the value of acquiring early (within hours after a negative high-sensitivity test) viral-load profiles to guide the appropriate analytical sensitivity and respiratory site for detecting earliest infections. Such data are challenging to acquire but critical to design optimal testing strategies with emerging variants in the current pandemic and to respond to future viral pandemics.

scholarly journals Towards the Direct Detection of Viral Materials at the Surface of Protective Face Masks via Infrared Spectroscopy

2021 ◽  
Author(s):  
Vanessa Schorer ◽  
Julian Haas ◽  
Robert Stach ◽  
Vjekoslav Kokoric ◽  
Ruediger Gross ◽  
...  
Keyword(s):  
Health Care ◽  
Infrared Spectroscopy ◽  
Large Scale ◽  
Direct Detection ◽  
Face Mask ◽  
Attenuated Total Reflection ◽  
Spectroscopic Techniques ◽  
Exhaled Breath ◽  
Virus Like Particles ◽  
Sampling Approach

Abstract The ongoing COVID-19 pandemic represents a considerable risk for the general public and especially for health care workers. To avoid an overloading of the health care system and to control transmission chains, the development of rapid and cost-effective techniques allowing for the reliable diagnosis of individuals with acute respiratory infections are crucial. Uniquely, the present study focuses on a direct face mask sampling approach, as worn (i.e., used) disposable face masks contain exogenous environmental constituents, as well as endogenously exhaled breath aerosols. Optical techniques – and specifically infrared (IR) molecular spectroscopic techniques - are promising tools for direct virus detection at the surface of such masks. In the present study, a rapid and non-destructive approach for monitoring exposure scenarios via medical face masks using attenuated total reflection infrared spectroscopy is presented. Complementarily, IR external reflection spectroscopy was evaluated in comparison for rapid mask analysis. The utility of a face mask-based sampling approach was demonstrated by differentiating water, proteins, and virus-like particles sampled onto the mask. Data analysis using multivariate statistical algorithms enabled unambiguously classifying spectral signatures of individual components and biospecies. This approach readily extends towards the rapid detection of SARS-CoV-2 – as shown herein for the example of virus-like particles which are morphologically equivalent to authentic virus - without any additional sample preparation or elaborate testing equipment at laboratory facilities. Therefore, this strategy may be implemented as a routine large-scale monitoring routine, e.g., at health care institutions, nursing homes, etc. ensuring the health and safety of medical personnel.

scholarly journals Use of Multiple Low Cost Carbon Dioxide Sensors to Measure Exhaled Breath Distribution with Face Mask Type and Wearing Behaviour

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6204
Author(s):  
Naveed Salman ◽  
Muhammad Waqas Khan ◽  
Michael Lim ◽  
Amir Khan ◽  
Andrew H. Kemp ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Low Cost ◽  
Co2 Concentration ◽  
Face Mask ◽  
Base Station ◽  
Exhaled Breath ◽  
Co2 Sensor ◽  
Improper Use ◽  
The Face ◽  
Carbon Dioxide Co2

The use of cloth face coverings and face masks has become widespread in light of the COVID-19 pandemic. This paper presents a method of using low cost wirelessly connected carbon dioxide (CO2) sensors to measure the effects of properly and improperly worn face masks on the concentration distribution of exhaled breath around the face. Four types of face masks are used in two indoor environment scenarios. CO2 as a proxy for exhaled breath is being measured with the Sensirion SCD30 CO2 sensor, and data are being transferred wirelessly to a base station. The exhaled CO2 is measured in four directions at various distances from the head of the subject, and interpolated to create spatial heat maps of CO2 concentration. Statistical analysis using the Friedman’s analysis of variance (ANOVA) test is carried out to determine the validity of the null hypotheses (i.e., distribution of the CO2 is same) between different experiment conditions. Results suggest CO2 concentrations vary little with the type of mask used; however, improper use of the face mask results in statistically different CO2 spatial distribution of concentration. The use of low cost sensors with a visual interpolation tool could provide an effective method of demonstrating the importance of proper mask wearing to the public.

scholarly journals Why simple face masks are unexpectedly efficient in reducing viral aerosol transmissions

2020 ◽  
Author(s):  
Steffen Freitag ◽  
Steven G. Howell ◽  
Kevin T. C. Jim
Keyword(s):  
Viral Load ◽  
Face Mask ◽  
Respiratory Viruses ◽  
Filtration Efficiency ◽  
Size Distributions ◽  
The Past ◽  
Apparent Inconsistency ◽  
Viral Aerosol ◽  
N95 Respirators ◽  
Aerosol Volume

SummaryDuring the current pandemic and in the past, shortages of high quality respirators have forced people to protect themselves with homemade face masks that filter poorly in comparison to N95 respirators 1–4 and are often designed in ways that makes them susceptible to leaks 5,6. Nevertheless, there is compelling epidemiological 7,8 and laboratory evidence 9–12 that face masks can be effective in impeding the spread of respiratory viruses such as influenza and SARS-CoV-2. Here we show that this apparent inconsistency can be resolved with a simple face mask model that combines our filtration efficiency measurements of various mask materials with existing data on exhaled aerosol characteristics. By reanalyzing these data we are able to reconcile the vastly different aerosol size distributions reported 13–19 and derive representative volume distributions for speech and breath aerosol. Multiplying filtration efficiency by those aerosol volumes, which are proportional to emitted viral load, shows that electrostatically charged materials perform the best but that even most uncharged fabrics remove > 85 % of breath and > 99 % of speech aerosol volume for exhaled particles < 10 µm in diameter. A leak model we develop shows the best uncharged fabric masks are made of highly air-permeable and often thin materials reducing viral load by up to 45 % and 50 % for breath and speech, respectively. Less permeable materials provide reduced protection because unfiltered air is forced through the leak. This can even render some charged materials inferior to uncharged household materials. Our model also shows that thin fabric masks provide protection for the wearer from aerosols expelled by another person reducing inhaled viral load by up to 20 % and 50 % and if leaks are avoided up to 35 % and 90 % for breath and speech, respectively.

scholarly journals Control of an Epidemic of SARS-CoV-2 by Assessing Transmissibility of Its Infected Cases in Absence of a Suitable Vaccine

2021 ◽  
Author(s):  
Bidisa Sarkar ◽  
Kamalesh Sarkar
Keyword(s):  
Viral Load ◽  
Infection Control ◽  
Control Policy ◽  
Face Mask ◽  
Contact Tracing ◽  
Population Mobility ◽  
Community Awareness ◽  
Ct Value ◽  
Management Protocol ◽  
Precautionary Measures

SARS-CoV-2 or Covid 19 and it’s pandemicity has been wreaking havoc in many countries worldwide. It is important to counter and contain the spread of Covid-19 using some effective infection control policies as we await an effective protection such as vaccine. Ahmedabad Model of Covid-19 Control could be used as an established epidemic management protocol due to COVID 19 infection. It relies on the Cycle Threshold (Ct) Value, which was used as a proxy marker for assessing initial viral load. It was evident that cases with higher viral load spread the disease at much higher rate compared to that of low viral load apart from population mobility and/or population density. Therefore, Ct value based segregation of infected cases with higher viral load along with contact tracing of them of previous 5 days is an effective epidemic control policy. It needs to be remembered that a section of infected cases is asymptomatic and capable of spreading infection in the community unknowingly. Hence, infection control practices must be accompanied with standard precautionary measures such as physical distancing, hand hygiene and wearing face mask. Community awareness is an integral part of it. Newer biotechnology based researches may be encouraged based on felt needs.

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