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.

scholarly journals Effects of COVID-19 during lockdown in Nepal

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Preeti Mahato ◽  
Pasang Tamang ◽  
Padam Simkhada ◽  
Prakash Shahi ◽  
Edwin van Teijlingen ◽  
...  
Keyword(s):  
Poverty Reduction ◽  
Negative Impact ◽  
Face Mask ◽  
Contact Tracing ◽  
Border Crossings ◽  
Health Coverage ◽  
Negative Effects ◽  
Social Distancing ◽  
Financial Condition ◽  
Precautionary Measures

Nepal started its full lockdown on March 24, 2020 and has been extended until 14 June 2020 as a precaution for prevention of COVID-19 infection. However, the strict lockdown has been criticised by many as not all the deaths are caused by COVID-19. The long and strict lockdown have had some negative effects in many aspects of health of an individual in the community. Many women are facing barriers to access maternity health care during the lockdown period and there has been rise in the suicidal behaviour such as sucidal attempt and actual suicide itself among the general population. As the lockdown began in Nepal, all the school and colleges were suspended, and children were forced to spend their time indoors and exams has been postponed leaving the students stressed about the uncertainty of their future. Social distancing, isolation and quarantine at home can result in isolated in an abusive home where there could be even more increase in abuse during such crisis. Millions of babies are missing the routine vaccinations which is a threat to global achievement in immunization. Apart from the rise in negative impact on health of Nepali people, there are other impacts related to health such as serious impacts on logistics and supply management including shortage of medicine and food supply; and impacts on farming including both production and sale. Nepal took several precautionary measures as a response towards COVID-19 such as   First, limiting international air travel, sealing the land border-crossings with India and introduction of social distancing measures. However, with rise in deaths due to non COVID related causes and negative impacts on economic and financial condition of the country, there is a need for the country to ease its lockdown.  Contact tracing, making face mask mandatory along with social distancing measure can be an alternative to lockdown for Nepal while the country is preparing to ease its lockdown. Social distancing, hygiene, lifestyle factors and PPE measures need to continue for long term, whilst we need to keep working on the big public health issues such as poverty reduction, improving access to health service to achieve universal health coverage. 

scholarly journals SARS-CoV-2 Load does not Predict Transmissibility in College Students

2021 ◽  
Author(s):  
Di Tian ◽  
Zhen Lin ◽  
Ellie M. Kriner ◽  
Dalton J. Esneault ◽  
Jonathan Tran ◽  
...  
Keyword(s):  
College Students ◽  
Viral Load ◽  
Population Level ◽  
Viral Transmission ◽  
Contact Tracing ◽  
Infected People ◽  
Individual Level ◽  
Ct Value ◽  
The Individual

AbstractSARS-CoV2 is highly contagious and the global spread has caused significant medical, social and economic impacts. Other than vaccination, effective public health measures, including contact tracing, isolation and quarantine, is critical for deterring viral transmission, preventing infection progression and resuming normal activities. Viral transmission is affected by many factors but the viral load and vitality could be among the most important ones. Although in vitro culture studies have indicated that the amount of virus isolated from infected people determines the successful rate of virus isolation, whether the viral load carried at the individual level would affect the transmissibility was not known. We aimed to determine whether the Ct value, a measurement of viral load by RT-PCR assay, could differentiate the spreader from the non-spreader in a population of college students. Our results indicate that while at the population level the Ct value is lower, suggesting a higher viral load, in the symptomatic spreaders than the asymptomatic non-spreaders, there is a significant overlap in the Ct values between the two groups. Thus Ct values, or the viral load, at the individual level could not predict the transmissibility. Our studies also suggest that a sensitive method to detect the presence of virus is needed to identify asymptomatic persons who may carry a low viral load but can still be infectious.

scholarly journals Viral Dynamics and Real-Time RT-PCR Ct Values Correlation with Disease Severity in COVID-19

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1091
Author(s):  
Ali A. Rabaan ◽  
Raghavendra Tirupathi ◽  
Anupam A Sule ◽  
Jehad Aldali ◽  
Abbas Al Mutair ◽  
...  
Keyword(s):  
Viral Load ◽  
Real Time ◽  
Disease Severity ◽  
False Negative ◽  
Influential Factors ◽  
Confirmatory Test ◽  
Acid Extraction ◽  
Rt Pcr ◽  
Viral Kinetics ◽  
Ct Value

Real-time RT-PCR is considered the gold standard confirmatory test for coronavirus disease 2019 (COVID-19). However, many scientists disagree, and it is essential to understand that several factors and variables can cause a false-negative test. In this context, cycle threshold (Ct) values are being utilized to diagnose or predict SARS-CoV-2 infection. This practice has a significant clinical utility as Ct values can be correlated with the viral load. In addition, Ct values have a strong correlation with multiple haematological and biochemical markers. However, it is essential to consider that Ct values might be affected by pre-analytic, analytic, and post-analytical variables such as collection technique, specimen type, sampling time, viral kinetics, transport and storage conditions, nucleic acid extraction, viral RNA load, primer designing, real-time PCR efficiency, and Ct value determination method. Therefore, understanding the interpretation of Ct values and other influential factors could play a crucial role in interpreting viral load and disease severity. In several clinical studies consisting of small or large sample sizes, several discrepancies exist regarding a significant positive correlation between the Ct value and disease severity in COVID-19. In this context, a revised review of the literature has been conducted to fill the knowledge gaps regarding the correlations between Ct values and severity/fatality rates of patients with COVID-19. Various databases such as PubMed, Science Direct, Medline, Scopus, and Google Scholar were searched up to April 2021 by using keywords including “RT-PCR or viral load”, “SARS-CoV-2 and RT-PCR”, “Ct value and viral load”, “Ct value or COVID-19”. Research articles were extracted and selected independently by the authors and included in the present review based on their relevance to the study. The current narrative review explores the correlation of Ct values with mortality, disease progression, severity, and infectivity. We also discuss the factors that can affect these values, such as collection technique, type of swab, sampling method, etc.

scholarly journals COVID-19 Pandemic Response Simulation in a Large City: Impact of Nonpharmaceutical Interventions on Reopening Society

2021 ◽  
pp. 0272989X2110030
Author(s):  
Serin Lee ◽  
Zelda B. Zabinsky ◽  
Judith N. Wasserheit ◽  
Stephen M. Kofsky ◽  
Shan Liu
Keyword(s):  
Large City ◽  
Face Mask ◽  
School Closure ◽  
Contact Tracing ◽  
The Novel ◽  
Agent Based ◽  
Social Distancing ◽  
Variable Compliance ◽  
Novel Coronavirus ◽  
Nonpharmaceutical Interventions

As the novel coronavirus (COVID-19) pandemic continues to expand, policymakers are striving to balance the combinations of nonpharmaceutical interventions (NPIs) to keep people safe and minimize social disruptions. We developed and calibrated an agent-based simulation to model COVID-19 outbreaks in the greater Seattle area. The model simulated NPIs, including social distancing, face mask use, school closure, testing, and contact tracing with variable compliance and effectiveness to identify optimal NPI combinations that can control the spread of the virus in a large urban area. Results highlight the importance of at least 75% face mask use to relax social distancing and school closure measures while keeping infections low. It is important to relax NPIs cautiously during vaccine rollout in 2021.

Data-driven inferences of agency-level risk and response communication on COVID-19 through social media-based interactions

2021 ◽  
Vol 19 (7) ◽  
pp. 59-82
Author(s):  
Md Ashraf Ahmed, PhD Candidate ◽  
Arif Mohaimin Sadri, PhD ◽  
M. Hadi Amini, PhD, DEng
Keyword(s):  
Public Health ◽  
Social Media ◽  
Information Dissemination ◽  
Topic Model ◽  
Face Mask ◽  
Community Response ◽  
Machine Learning Algorithms ◽  
Data Driven ◽  
Contact Tracing ◽  
Online Social Media

Risk perception and risk averting behaviors of public agencies in the emergence and spread of COVID-19 can be retrieved through online social media (Twitter), and such interactions can be echoed in other information outlets. This study collected time-sensitive online social media data and analyzed patterns of health risk communication of public health and emergency agencies in the emergence and spread of novel coronavirus using data-driven methods. The major focus is toward understanding how policy-making agencies communicate risk and response information through social media during a pandemic and influence community response—ie, timing of lockdown, timing of reopening, etc.—and disease outbreak indicators—ie, number of confirmed cases and number of deaths. Twitter data of six major public organizations (1,000-4,500 tweets per organization) are collected from February 21, 2020 to June 6, 2020. Several machine learning algorithms, including dynamic topic model and sentiment analysis, are applied over time to identify the topic dynamics over the specific timeline of the pandemic. Organizations emphasized on various topics—eg, importance of wearing face mask, home quarantine, understanding the symptoms, social distancing and contact tracing, emerging community transmission, lack of personal protective equipment, COVID-19 testing and medical supplies, effect of tobacco, pandemic stress management, increasing hospitalization rate, upcoming hurricane season, use of convalescent plasma for COVID-19 treatment, maintaining hygiene, and the role of healthcare podcast in different timeline. The findings can benefit emergency management, policymakers, and public health agencies to identify targeted information dissemination policies for public with diverse needs based on how local, federal, and international agencies reacted to COVID-19.

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 The first 100 days of SARS-CoV-2 control in Vietnam

2020 ◽  
Author(s):  
Thai Quang Pham ◽  
Maia Rabaa ◽  
Luong Huy Duong ◽  
Tan Quang Dang ◽  
Quang Dai Tran ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Severe Disease ◽  
Steering Committee ◽  
International Travel ◽  
Control Measures ◽  
Contact Tracing ◽  
Population Mobility ◽  
Early Introduction ◽  
Mobility Data ◽  
Travel Restrictions

Background: One hundred days after SARS-CoV-2 was first reported in Vietnam on January 23rd, 270 cases have been confirmed, with no deaths. We describe the control measures used and their relationship with imported and domestically-acquired case numbers. Methods: Data on the first 270 SARS-CoV-2 infected cases and the timing and nature of control measures were captured by Vietnam's National Steering Committee for COVID-19 response. Apple and Google mobility data provided population movement proxies. Serial intervals were calculated from 33 infector-infectee pairs and used to estimate the proportion of pre-symptomatic transmission events and time-varying reproduction numbers. Results: After the first confirmed case on January 23rd, the Vietnamese Government initiated mass communications measures, contact tracing, mandatory 14-day quarantine, school and university closures, and progressive flight restrictions. A national lockdown was implemented between April 1st and 22nd. Around 200,000 people were quarantined and 266,122 RT-PCR tests conducted. Population mobility decreased progressively before lockdown. 60% (163/270) of cases were imported; 43% (89/208) of resolved infections were asymptomatic. 21 developed severe disease, with no deaths. The serial interval was 3.24 days, and 27.5% (95% confidence interval, 15.7%-40.0%) of transmissions occurred pre-symptomatically. Limited transmission amounted to a maximum reproduction number of 1.15 (95% confidence interval, 0.37-2.36). No community transmission has been detected since April 15th. Conclusions: Vietnam has controlled SARS-CoV-2 spread through the early introduction of communication, contact-tracing, quarantine, and international travel restrictions. The value of these interventions is supported by the high proportion of asymptomatic cases and imported cases, and evidence for substantial pre-symptomatic transmission.

scholarly journals Transmission dynamics and the effects of non-pharmaceutical interventions in the COVID-19 outbreak resurged in Beijing, China: a descriptive and modelling study

BMJ Open ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. e047227
Author(s):  
Xiaoming Cui ◽  
Lin Zhao ◽  
Yuhao Zhou ◽  
Xin Lin ◽  
Runze Ye ◽  
...  
Keyword(s):  
Close Contact ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Population Mobility ◽  
Wholesale Market ◽  
The People ◽  
Spatiotemporal Analyses ◽  
Epidemiological Characteristics ◽  
Pharmaceutical Interventions ◽  
Modelling Study

ObjectiveTo evaluate epidemiological characteristics and transmission dynamics of COVID-19 outbreak resurged in Beijing and to assess the effects of three non-pharmaceutical interventions.DesignDescriptive and modelling study based on surveillance data of COVID-19 in Beijing.SettingOutbreak in Beijing.ParticipantsThe database included 335 confirmed cases of COVID-19.MethodsTo conduct spatiotemporal analyses of the outbreak, we collected individual records on laboratory-confirmed cases of COVID-19 from 11 June 2020 to 5 July 2020 in Beijing, and visitor flow and products transportation data of Xinfadi Wholesale Market. We also built a modified susceptible-exposed-infected-removed model to investigate the effect of interventions deployed in Beijing.ResultsWe found that the staff working in the market (52.2%) and the people around 10 km to this epicentre (72.5%) were most affected, and the population mobility entering-exiting Xinfadi Wholesale Market significantly contributed to the spread of COVID-19 (p=0.021), but goods flow of the market had little impact on the virus spread (p=0.184). The prompt identification of Xinfadi Wholesale Market as the infection source could have avoided a total of 25 708 (95% CI 13 657 to 40 625) cases if unnoticed transmission lasted for a month. Based on the model, we found that active screening on targeted population by nucleic acid testing alone had the most significant effect.ConclusionsThe non-pharmaceutical interventions deployed in Beijing, including localised lockdown, close-contact tracing and community-based testing, were proved to be effective enough to contain the outbreak. Beijing has achieved an optimal balance between epidemic containment and economic protection.

Detecting SARS-CoV-2 by Realtime RT-PCR in clinical samples collected in the North of Vietnam

2021 ◽  
Vol 30 (9) ◽  
pp. 11-17
Author(s):  
Hoang Vu Mai Phuong ◽  
Ung Thi Hong Trang ◽  
Nguyen Vu Son ◽  
Le Thi Thanh ◽  
Nguyen Le Khanh Hang ◽  
...  
Keyword(s):  
Viral Load ◽  
Average Rate ◽  
Clinical Samples ◽  
Viet Nam ◽  
Rt Pcr ◽  
Ct Value ◽  
The North ◽  
Viral Load Data ◽  
The Mean ◽  
High Level

From January to August 2020, Northern Viet Nam faced a COVID-19 outbreak, up to September 2020, there were 1122 confrmed cases of SARS-CoV-2, of which 465 cases were imported from Europe, America and Asia, 657 cases were identifed domestically. A total of 30,686 samples were collected during the SARS-CoV-2 outbreak in Northern Viet Nam and examined by Real-time RT-PCR using primers and probe from Charite - Berlin protocol. This study showed the initial results of SARS-CoV-2 detection and RNA quantitative in positive samples. The positive rate was 0.8%, ranging from 0.4 to 3.5% according to collection sites. Out of 251 positive samples, the mean Ct value was 28 (IQR: 22.3-32; range 14 - 38). The positive samples had a Ct value below 30 was 68.5%, there was no signifcant difference between the Ct value of the group ≤ 30 and > 30. The mean of the RNA copies/µl was 8.4.107, (IQR: 2.29.106 - 1.83.109 RNA copies/µl, range: 1.95.103 – 4.95.1011). In the group of imported COVID-19 cases, the rate of virus at low level was 29%, an average was 56% and at high level was 15%. In the community groups, the viral load data showed that the average rate at low, intermediate and high level were 20%, 63% and 17% respectively. The proportion of high-level viral load may raise an alert to start the quarantine process to reduce the transmission of SARS-CoV-2

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