scholarly journals Transmission frequency of covid-19 through pre-symptomatic and asymptomatic patients in AJK: A report of 201 cases

2021 ◽  
Author(s):  
Majid Mahmood ◽  
Noor-ul-ain Ilyas ◽  
Muhammad Faraz Khan ◽  
Muhammad Naseem Hasrat
Keyword(s):  
Disease Transmission ◽  
Human Population ◽  
Virus Disease ◽  
Transmission Rate ◽  
Retrospective Case ◽  
Transmission Frequency ◽  
Infection Transmission ◽  
Asymptomatic Patients ◽  
History Of

Abstract Background: Corona virus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2, declared as “once-in-a-century” pandemic, has affected about entire human population. Till now, the most promising control strategy is to block the transmission which will never be effective without completely knowing the transmission patterns.Methods: This was a retrospective case to case study aiming to estimate and calculate the transmission rate of COVID-19 through pre-symptomatic and asymptomatic patients. Contact history of included positive cases during the period of 24 hours before appearance of symptoms and infection confirmation for symptomatic and asymptomatic cases respectively was traced for disease transmission. Results: Overall, a total of 201 cases had contacted with 7168 people in last 24 hours with an average of 35.66 contacts per patient ranging from a minimum of 4 to maximum of 87 contacts (Meetings). Out of 7168 meeting persons, the infection was traced in 64 (0.89%) persons. For 155 symptomatic patients, a total of 5611 contacting persons were traced before appearance of symptoms (pre-symptomatic) in last 24 hours with an average of 36.20 meetings per patient. The infection was transmitted in 63 (1.12%) people and remaining 5548 (98.88%) were remained uninfected. Out of the 63 transmissions, 62 (98.4%) were traced within last 6 hours before the onset of symptoms while only 1 was traced from 6-12 hours before symptoms. A total of 1557 persons were traced having meeting/contacts with asymptomatic cases in last 24 hours before their infection confirmation. Out of these 1557 persons, only 1 was found to be infected and the infection rate was calculated to be 0.06%. Conclusion: The study concludes that the risk of pre-symptomatic transmission of infection is low (1.12%) and it becomes very rare in contacts made longer than 6 hours before onset of symptoms. The infection transmission is traced as long as about 9 hours before the appearance of clear symptoms in the patients but the incidence was as low as about 0.02% of the total contacts in that period. Transmission frequency by asymptomatic patients is also rare (0.06%) in the studied population.

scholarly journals Transmission frequency of covid-19 through pre-symptomatic and asymptomatic patients in AJK: A report of 201 cases

2021 ◽  
Author(s):  
Majid Mahmood ◽  
Noor-ul-ain Ilyas ◽  
Muhammad Khan ◽  
Muhammad Hasrat
Keyword(s):  
Disease Transmission ◽  
Human Population ◽  
Virus Disease ◽  
Transmission Rate ◽  
Retrospective Case ◽  
Transmission Frequency ◽  
Infection Transmission ◽  
Asymptomatic Patients ◽  
History Of

Abstract Background: Corona virus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, declared as “once-in-a-century” pandemic, has affected about entire human population. Till now, the most promising control strategy is to block the transmission which will never be effective without completely knowing the transmission patterns.Methods: This was a retrospective case to case study aiming to estimate and calculate the transmission rate of COVID-19 through pre-symptomatic and asymptomatic patients. Contact history of included positive cases during the period of 24 hours before appearance of symptoms and infection confirmation for symptomatic and asymptomatic cases respectively was traced for disease transmission. Results: Overall, a total of 201 cases had contacted with 7168 people in last 24 hours with an average of 35.66 contacts per patient ranging from a minimum of 4 to maximum of 87 contacts (Meetings). Out of 7168 meeting persons, the infection was traced in 64 (0.89%) persons. For 155 symptomatic patients, a total of 5611 contacting persons were traced before appearance of symptoms (pre-symptomatic) in last 24 hours with an average of 36.20 meetings per patient. The infection was transmitted in 63 (1.12%) people and remaining 5548 (98.88%) were remained uninfected. Out of the 63 transmissions, 62 (98.4%) were traced within last 6 hours before the onset of symptoms while only 1 was traced from 6-12 hours before symptoms. A total of 1557 persons were traced having meeting/contacts with asymptomatic cases in last 24 hours before their infection confirmation. Out of these 1557 persons, only 1 was found to be infected and the infection rate was calculated to be 0.06%. Conclusion: The study concludes that the risk of pre-symptomatic transmission of infection is low (1.12%) and it becomes very rare in contacts made longer than 6 hours before onset of symptoms. The infection transmission is traced as long as about 9 hours before the appearance of clear symptoms in the patients but the incidence was as low as about 0.02% of the total contacts in that period. Transmission frequency by asymptomatic patients is also rare (0.06%) in the studied population.

scholarly journals Transmission frequency of COVID-19 through pre-symptomatic and asymptomatic patients in AJK: A report of 201 cases

2021 ◽  
Author(s):  
Majid Mahmood ◽  
Noor-ul-ain Ilyas ◽  
Muhammad Faraz Khan ◽  
Muhammad Naseem Hasrat
Keyword(s):  
Disease Transmission ◽  
Human Population ◽  
Virus Disease ◽  
Transmission Rate ◽  
Retrospective Case ◽  
Transmission Frequency ◽  
Infection Transmission ◽  
Asymptomatic Patients ◽  
History Of

Abstract Background: Corona virus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2, declared as “once-in-a-century” pandemic, has affected about entire human population. Till now, the most promising control strategy is to block the transmission which will never be effective without completely knowing the transmission patterns.Methods: This was a retrospective case to case study aiming to estimate and calculate the transmission rate of COVID-19 through pre-symptomatic and asymptomatic patients. Contact history of included positive cases during the period of 24 hours before appearance of symptoms and infection confirmation for symptomatic and asymptomatic cases respectively was traced for disease transmission. Results: Overall, a total of 201 cases had contacted with 7168 people in last 24 hours with an average of 35.66 contacts per patient ranging from a minimum of 4 to maximum of 87 contacts (Meetings). Out of 7168 meeting persons, the infection was traced in 64 (0.89%) persons. For 155 symptomatic patients, a total of 5611 contacting persons were traced before appearance of symptoms (pre-symptomatic) in last 24 hours with an average of 36.20 meetings per patient. The infection was transmitted in 63 (1.12%) people and remaining 5548 (98.88%) were remained uninfected. Out of the 63 transmissions, 62 (98.4%) were traced within last 6 hours before the onset of symptoms while only 1 was traced from 6-12 hours before symptoms. A total of 1557 persons were traced having meeting/contacts with asymptomatic cases in last 24 hours before their infection confirmation. Out of these 1557 persons, only 1 was found to be infected and the infection rate was calculated to be 0.06%. Conclusion: The study concludes that the risk of pre-symptomatic transmission of infection is low (1.12%) and it becomes very rare in contacts made longer than 6 hours before onset of symptoms. The infection transmission is traced as long as about 9 hours before the appearance of clear symptoms in the patients but the incidence was as low as about 0.02% of the total contacts in that period. Transmission frequency by asymptomatic patients is also rare (0.06%) in the studied population.

scholarly journals Transmission frequency of covid-19 through pre-symptomatic and asymptomatic patients in AJK: A report of 201 cases

2021 ◽  
Author(s):  
Majid Mahmood ◽  
Noor-ul-ain Ilyas ◽  
Muhammad Faraz Khan ◽  
Muhammad Naseem Hasrat
Keyword(s):  
Disease Transmission ◽  
Human Population ◽  
Virus Disease ◽  
Transmission Rate ◽  
Retrospective Case ◽  
Transmission Frequency ◽  
Infection Transmission ◽  
Asymptomatic Patients ◽  
History Of

Abstract Background: Corona virus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2, declared as “once-in-a-century” pandemic, has affected about entire human population. Till now, the most promising control strategy is to block the transmission which will never be effective without completely knowing the transmission patterns.Methods: This was a retrospective case to case study aiming to estimate and calculate the transmission rate of COVID-19 through pre-symptomatic and asymptomatic patients. Contact history of included positive cases during the period of 24 hours before appearance of symptoms and infection confirmation for symptomatic and asymptomatic cases respectively was traced for disease transmission. Results: Overall, a total of 201 cases had contacted with 7168 people in last 24 hours with an average of 35.66 contacts per patient ranging from a minimum of 4 to maximum of 87 contacts (Meetings). Out of 7168 meeting persons, the infection was traced in 64 (0.89%) persons. For 155 symptomatic patients, a total of 5611 contacting persons were traced before appearance of symptoms (pre-symptomatic) in last 24 hours with an average of 36.20 meetings per patient. The infection was transmitted in 63 (1.12%) people and remaining 5548 (98.88%) were remained uninfected. Out of the 63 transmissions, 62 (98.4%) were traced within last 6 hours before the onset of symptoms while only 1 was traced from 6-12 hours before symptoms. A total of 1557 persons were traced having meeting/contacts with asymptomatic cases in last 24 hours before their infection confirmation. Out of these 1557 persons, only 1 was found to be infected and the infection rate was calculated to be 0.06%. Conclusion: The study concludes that the risk of pre-symptomatic transmission of infection is low (1.12%) and it becomes very rare in contacts made longer than 6 hours before onset of symptoms. The infection transmission is traced as long as about 9 hours before the appearance of clear symptoms in the patients but the incidence was as low as about 0.02% of the total contacts in that period. Transmission frequency by asymptomatic patients is also rare (0.06%) in the studied population.

scholarly journals Transmission frequency of COVID-19 through pre-symptomatic and asymptomatic patients in AJK: a report of 201 cases

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Majid Mahmood ◽  
Noor-ul-ain Ilyas ◽  
Muhammad Faraz Khan ◽  
Muhammad Naseem Hasrat ◽  
Nicholas Richwagen
Keyword(s):  
Disease Transmission ◽  
Transmission Rate ◽  
Human Life ◽  
Influenza Pandemic ◽  
Symptomatic Infection ◽  
Transmission Frequency ◽  
Asymptomatic Patients ◽  
History Of ◽  
1918 Influenza ◽  
Asymptomatic Individuals

Abstract Background The COVID-19 pandemic is a catastrophic global phenomenon, affecting human life in a way unseen since the 1918 influenza pandemic. Effective management of this threat requires halting transmission, a strategy requiring accurate knowledge of SARS-CoV-2 transmission patterns. Methods This was a retrospective contact study aiming to estimate the transmission rate of COVID-19 by tracing contacts in symptomatic, pre-symptomatic, and asymptomatic patients. History of patients’ contacts during 24 h before appearance of symptoms or infection confirmation was traced for disease transmission. Results Overall, a total of 201 COVID-19 patients had contact with 7168 people in 24 h with an average of 35.66 contacts per patient, ranging from a minimum of 4 to maximum of 87 contacts (meetings). Out of 7168 persons met, infection was detected in 64 (0.89%). For the 155 symptomatic patients, a total of 5611 contacted persons were traced before appearance of symptoms (pre-symptomatic) in last 24 h with an average of 36.20 meetings per patient. The infection was transmitted in 63 (1.12%) people with 5548 (98.88%) remaining uninfected. Out of the 63 transmissions, 62 (98.4%) were traced within 6 h before symptom onset, while only 1 was identified in the 6–12 h timeframe before symptoms. A total of 1557 persons were traced having meeting/contacts with asymptomatic cases in last 24 h before infection confirmation. Out of these 1557 persons, only 1 was found to be infected and the infection rate was calculated to be 0.06%. Statistically, the transmission rate by pre-symptomatic patients was found to be significantly higher than the transmission rate by asymptomatic individuals (P < 0.05). Conclusion In the studied population, the risk of pre-symptomatic and asymptomatic transmission of COVID-19 was low, with transmission risks of 1.12% and 0.06% respectively. Pre-symptomatic infection becomes very rare in contacts made longer than 6 h before onset of symptoms. The infection transmission is traced as long as about 9 h before the appearance of clear symptoms in the patients, but the incidence rate was as low as about 0.02% of the total contacts in that period.

scholarly journals Modeling the impact of school reopening and contact tracing strategies on Covid-19 dynamics in different epidemiologic settings in Brazil

2021 ◽  
Author(s):  
Marcelo Eduardo Borges ◽  
Leonardo Souto Ferreira ◽  
Silas Poloni ◽  
Ângela Maria Bagattini ◽  
Caroline Franco ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Transmission Rate ◽  
Disease Incidence ◽  
Demographic Data ◽  
School Closure ◽  
Mitigation Measures ◽  
Contact Tracing ◽  
School Closures ◽  
Infection Transmission ◽  
The Impact

Among the various non–pharmaceutical interventions implemented in response to the Covid–19 pandemic during 2020, school closures have been in place in several countries to reduce infection transmission. Nonetheless, the significant short and long–term impacts of prolonged suspension of in–person classes is a major concern. There is still considerable debate around the best timing for school closure and reopening, its impact on the dynamics of disease transmission, and its effectiveness when considered in association with other mitigation measures. Despite the erratic implementation of mitigation measures in Brazil, school closures were among the first measures taken early in the pandemic in most of the 27 states in the country. Further, Brazil delayed the reopening of schools and stands among the countries in which schools remained closed for the most prolonged period in 2020. To assess the impact of school reopening and the effect of contact tracing strategies in rates of Covid–19 cases and deaths, we model the epidemiological dynamics of disease transmission in 3 large urban centers in Brazil under different epidemiological contexts. We implement an extended SEIR model stratified by age and considering contact networks in different settings – school, home, work, and elsewhere, in which the infection transmission rate is affected by various intervention measures. After fitting epidemiological and demographic data, we simulate scenarios with increasing school transmission due to school reopening. Our model shows that reopening schools results in a non–linear increase of reported Covid-19 cases and deaths, which is highly dependent on infection and disease incidence at the time of reopening. While low rates of within[&ndash]school transmission resulted in small effects on disease incidence (cases/100,000 pop), intermediate or high rates can severely impact disease trends resulting in escalating rates of new cases even if other interventions remain unchanged. When contact tracing and quarantining are restricted to school and home settings, a large number of daily tests is required to produce significant effects of reducing the total number of hospitalizations and deaths. Our results suggest that policymakers should carefully consider the epidemiological context and timing regarding the implementation of school closure and return of in-person school activities. Also, although contact tracing strategies are essential to prevent new infections and outbreaks within school environments, our data suggest that they are alone not sufficient to avoid significant impacts on community transmission in the context of school reopening in settings with high and sustained transmission rates.

scholarly journals Seroprevalence of anti-SARS-CoV-2 IgG in asymptomatic and pauci-symptomatic people over a 5 month survey in Argentina

2021 ◽  
Vol 45 ◽  
pp. 1
Author(s):  
Luz María Rodeles ◽  
Luz María Peverengo ◽  
Romina Benítez ◽  
Nadia Benzaquen ◽  
Priscila Serravalle ◽  
...  
Keyword(s):  
Transmission Rate ◽  
Large Population ◽  
Total Sample ◽  
Cross Sectional Study ◽  
Santa Fe ◽  
Igg Antibody ◽  
Cross Sectional ◽  
Asymptomatic Patients ◽  
History Of ◽  
Probabilistic Sample

Objective. To evaluate the seroprevalence of COVID-19 infection in pauci-symptomatic and asymptomatic people, the associated epidemiological factors, and IgG antibody kinetic over a 5-month period to get a better knowledge of the disease transmissibility and the rate of susceptible persons that might be infected. Methods. Seroprevalence was evaluated by a cross-sectional study based on the general population of Santa Fe, Argentina (non-probabilistic sample) carried out between July and November 2020. A subgroup of 20 seropositive individuals was followed-up to analyze IgG persistence. For the IgG anti-SARS-CoV-2 antibodies detection, the COVID-AR IgG® ELISA kit was used. Results. 3 000 individuals were included conforming asymptomatic and pauci-symptomatic groups (n=1 500 each). From the total sample, only 8.83% (n=265) presented reactivity for IgG anti-SARS-CoV-2. A significant association was observed between positive anti-SARS-CoV-2 IgG and a history of contact with a confirmed case; the transmission rate within households was approximately 30%. In the pauci-symptomatic group, among the seropositive ones, anosmia and fever presented an OR of 16.8 (95% CI 9.5-29.8) and 2.7 (95% CI 1.6-4.6), respectively (p <0.001). In asymptomatic patients, IgG levels were lower compared to pauci-symptomatic patients, tending to decline after 4 months since the symptoms onset. Conclusion. We observed a low seroprevalence, suggestive of a large population susceptible to the infection. Anosmia and fever were independent significant predictors for seropositivity. Asymptomatic patients showed lower levels of antibodies during the 5-month follow-up. IgG antibodies tended to decrease over the end of this period regardless of symptoms.

scholarly journals A model and predictions for COVID-19 considering population behavior and vaccination

2021 ◽  
Author(s):  
Thomas Usherwood ◽  
Zachary LaJoie ◽  
Vikas Srivast
Keyword(s):  
United States ◽  
Disease Transmission ◽  
Transmission Rate ◽  
Time History ◽  
The United States ◽  
High Rate ◽  
Safety Level ◽  
History Of ◽  
Approach Zero ◽  
And Behavior

Abstract The effect of vaccination coupled with the behavioral response of the population is not well understood. Our model incorporates two important dynamically varying population behaviors: level of caution and sense of safety. Level of caution increases with infectious cases, while an increasing sense of safety with increased vaccination lowers precautions. Our model accurately reproduces the complete time history of COVID-19 infections for various regions of the United States. We propose a parameter d_I as a direct measure of a population’s caution against an infectious disease that can be obtained from the infectious cases. The model provides quantitative measures of highest disease transmission rate, effective transmission rate, and cautionary behavior. We predict future COVID-19 trends in the United States accounting for vaccine rollout and behavior. Although a high rate of vaccination is critical to quickly ending the pandemic, a return towards pre-pandemic social behavior due to increased sense of safety during vaccine deployment can cause an alarming surge in infections. Our results predict that at the current rate of vaccination, the new infection cases for COVID-19 in the United States will approach zero by August 2021. This model can be used for other regions and for future epidemics and pandemics.

scholarly journals Continuing problems for Amazon river turtles

Oryx ◽  
1987 ◽  
Vol 21 (1) ◽  
pp. 25-28 ◽  
Author(s):  
Andrew D. Johns
Keyword(s):  
Economic Development ◽  
Human Population ◽  
Amazon River ◽  
Commercial Species ◽  
Podocnemis Expansa ◽  
History Of ◽  
Wildlife Populations ◽  
Over Exploitation ◽  
River Turtles

Amazon river turtles have a long history of over-exploitation, firstly for oil production, and lately as a luxury food for the expanding human population. In many areas, the populations of the two main commercial species Podocnemis expansa and P. unifilis are now so low that extinction is in sight. In 1985 a WWF-US project aimed at investigating interactions between economic development and wildlife populations conducted a case-study of the exploitation of turtles on the River Tefé in western Brazilian Amazonia.

scholarly journals Risk of disease transmission from flexible nasoendoscopy during the coronavirus disease 2019 pandemic

2021 ◽  
Vol 135 (3) ◽  
pp. 246-249 ◽  
Author(s):  
F G Kavanagh ◽  
C Connolly ◽  
E Farrell ◽  
D Callanan ◽  
D Brinkman ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Disease Transmission ◽  
Healthcare Workers ◽  
Additional Data ◽  
Protective Equipment ◽  
Infection Transmission ◽  
Asymptomatic Patients ◽  
Upper Limits ◽  
Red Flag ◽  
Risk Of Disease

AbstractBackgroundConcerns have emerged regarding infection transmission during flexible nasoendoscopy.MethodsInformation was gathered prospectively on flexible nasoendoscopy procedures performed between March and June 2020. Patients and healthcare workers were followed up to assess for coronavirus disease 2019 development. One-sided 97.5 per cent Poisson confidence intervals were calculated for upper limits of risk where zero events were observed.ResultsA total of 286 patients were recruited. The most common indication for flexible nasoendoscopy was investigation of ‘red flag’ symptoms (67 per cent). Forty-seven patients (16 per cent, 95 per cent confidence interval = 13–21 per cent) had suspicious findings on flexible nasoendoscopy requiring further investigation. Twenty patients (7.1 per cent, 95 per cent confidence interval = 4.4–11 per cent) had new cancer diagnoses. Zero coronavirus disease 2019 infections were recorded in the 273 patients. No. 27 endoscopists (the doctors and nurses who carried out the procedures) were followed up.The risk of developing coronavirus disease 2019 after flexible nasoendoscopy was determined to be 0–1.3 per cent.ConclusionThe risk of coronavirus disease 2019 transmission associated with performing flexible nasoendoscopy in asymptomatic patients, while using appropriate personal protective equipment, is very low. Additional data are required to confirm these findings in the setting of further disease surges.

scholarly journals A model and predictions for COVID-19 considering population behavior and vaccination

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thomas Usherwood ◽  
Zachary LaJoie ◽  
Vikas Srivastava
Keyword(s):  
United States ◽  
Disease Transmission ◽  
Transmission Rate ◽  
Time History ◽  
The United States ◽  
High Rate ◽  
Safety Level ◽  
History Of ◽  
Approach Zero ◽  
And Behavior

AbstractThe effect of vaccination coupled with the behavioral response of the population is not well understood. Our model incorporates two important dynamically varying population behaviors: level of caution and sense of safety. Level of caution increases with infectious cases, while an increasing sense of safety with increased vaccination lowers precautions. Our model accurately reproduces the complete time history of COVID-19 infections for various regions of the United States. We propose a parameter $$d_I$$ d I as a direct measure of a population’s caution against an infectious disease that can be obtained from the infectious cases. The model provides quantitative measures of highest disease transmission rate, effective transmission rate, and cautionary behavior. We predict future COVID-19 trends in the United States accounting for vaccine rollout and behavior. Although a high rate of vaccination is critical to quickly ending the pandemic, a return towards pre-pandemic social behavior due to increased sense of safety during vaccine deployment can cause an alarming surge in infections. Our results predict that at the current rate of vaccination, the new infection cases for COVID-19 in the United States will approach zero by August 2021. This model can be used for other regions and for future epidemics and pandemics.

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