Modeling the impacts of contact tracing on an epidemic with asymptomatic infection

2022 ◽  
Vol 416 ◽  
pp. 126754
Author(s):  
Yahong Chen ◽  
He Huang
Keyword(s):  
Asymptomatic Infection ◽  
Contact Tracing

scholarly journals Prevalence of asymptomatic COVID-19 infection using a seroepidemiological survey

2020 ◽  
Vol 148 ◽  
Author(s):  
M. Shakiba ◽  
M. Nazemipour ◽  
A. Heidarzadeh ◽  
M. A. Mansournia
Keyword(s):  
Public Health ◽  
Rapid Test ◽  
Asymptomatic Infection ◽  
Mitigation Strategy ◽  
Contact Tracing ◽  
Cross Sectional ◽  
Health Measures ◽  
Critical Measure ◽  
History Of ◽  
Guilan Province

Abstract The prevalence of asymptomatic infection by coronavirus disease 2019 (COVID-19) as a critical measure for effectiveness of mitigation strategy has been reported to be widely varied. In this study, we aimed to determine the prevalence of asymptomatic infection using serosurvey on general population. In a cross-sectional seroprevalence survey in Guilan province, Iran, the specific antibody against COVID-19 in a representative sample was detected using rapid test kits. Among 117 seropositive subjects, prevalence of asymptomatic infection was determined based on the history of symptoms during the preceding 3 months. The design-adjusted prevalence of asymptomatic infection was 57.2% (95% confidence interval (CI) 44–69). The prevalence was significantly lower in subjects with previous contacts to COVID-19 patients (12%, 95% CI 2–49) than others without (69%, 95% CI, 46–86). The lowest prevalence was for painful body symptom (74.4%). This study revealed that more than half of the infected COVID-19 patients had no symptoms. The implications of our findings include the importance of adopting public health measures such as social distancing and inefficiency of contact tracing to interrupt epidemic transmission.

Silent upper genital tract chlamydial infection and disease in women

1997 ◽  
Vol 8 (5) ◽  
pp. 329-331 ◽  
Author(s):  
S J Tait ◽  
I A Duthie ◽  
D Taylor-Robinson
Keyword(s):  
Genital Tract ◽  
Chlamydial Infection ◽  
Past History ◽  
Fluorescent Antibody ◽  
Asymptomatic Infection ◽  
Contact Tracing ◽  
Menstrual Phase ◽  
Chlamydia Trachomatis Infection ◽  
Partner Change ◽  
Phase Interval

To find what proportion of women with endocervical Chlamydia trachomatis infection had asymptomatic infection of the upper genital tract, 10 women with neither gonorrhoea nor signs, symptoms or a past history of pelvic inflammatory disease were laparoscoped. Swabs from the fimbriae and pouch of Douglas were tested for C. trachomatis by tissue culture, enzyme immunoassay, direct fluorescent antibody and polymerase chain reaction techniques. Four of the women had an upper genital tract chlamydial infection. Neither laparoscopic appearances, menstrual phase, interval since last intercourse, partner change nor other coincidental genital infection was associated with the upper genital tract spread. These findings suggest that careful investigation, immediate treatment and contact tracing are mandatory when asymptomatic endocervical chlamydial infection is discovered.

scholarly journals What do we know about SARS-CoV-2 transmission? A systematic review and meta-analysis of the secondary attack rate, serial interval, and asymptomatic infection

2020 ◽  
Author(s):  
Wee Chian Koh ◽  
Lin Naing ◽  
Muhammad Ali Rosledzana ◽  
Mohammad Fathi Alikhan ◽  
Liling Chaw ◽  
...  
Keyword(s):  
Systematic Review ◽  
Attack Rate ◽  
Meta Analysis ◽  
Original Data ◽  
Asymptomatic Infection ◽  
Control Measures ◽  
Transmission Risk ◽  
Contact Tracing ◽  
Random Effects Models ◽  
Serial Interval

Background Current SARS-CoV-2 containment measures rely on the capacity to control person-to-person viral transmission. Effective prioritization of these measures can be determined by understanding SARS-CoV-2 transmission dynamics. We conducted a systematic review and meta-analyses of three parameters: (i) secondary attack rate (SAR) in various settings, (ii) clinical onset serial interval (SI), and (iii) the proportion of asymptomatic infection. Methods and Findings We searched PubMed, medRxiv, and bioRxiv databases between January 1, 2020, and May 15, 2020, for articles describing SARS-CoV-2 attack rate, SI, and asymptomatic infection. Studies were included if they presented original data for estimating point estimates and 95% confidence intervals of the three parameters. Random effects models were constructed to pool SAR, mean SI, and asymptomatic proportion. Risk ratios were used to examine differences in transmission risk by setting, type of contact, and symptom status of the index case. Publication and related bias were assessed by funnel plots and Egger's meta-regression test for small-study effects. Our search strategy for SAR, SI, and asymptomatic infection identified 459, 572, and 1624 studies respectively. Of these, 20 studies met the inclusion criteria for SAR, 18 studies for SI, and 66 studies for asymptomatic infection. We estimated the pooled household SAR at 15.4% (95% CI: 12.2%, 18.7%) compared to 4.0% (95% CI: 2.8%, 5.2%) in non-household settings. We observed variation across settings; however, the small number of studies limited power to detect associations and sources of heterogeneity. SAR of symptomatic index cases is significantly higher than cases that were symptom-free at diagnosis (RR 2.55, 95% CI: 1.47, 4.45). Adults appear to be more susceptible to transmission than children (RR 1.40, 95% CI: 1.00, 1.96). The pooled mean SI is estimated at 4.87 days (95% CI: 3.98, 5.77). The pooled proportion of cases who had no symptoms at diagnosis is 25.9% (95% CI: 18.8%, 33.1%). Conclusions Based our pooled estimates, 10 infected symptomatic persons living with 100 contacts would result in 15 additional cases in <5 days. To be effective, quarantine of contacts should occur within 3 days of symptom onset. If testing and tracing relies on symptoms, one-quarter of cases would be missed. As such, while aggressive contact tracing strategies may be appropriate early in an outbreak, as it progresses, control measures should transition to account for SAR variability across settings. Targeted strategies focusing on high-density enclosed settings may be effective without overly restricting social movement.

scholarly journals A Prospective Cohort Study in Nonhospitalized Household Contacts With Severe Acute Respiratory Syndrome Coronavirus 2 Infection: Symptom Profiles and Symptom Change Over Time

2020 ◽  
Author(s):  
Anna R Yousaf ◽  
Lindsey M Duca ◽  
Victoria Chu ◽  
Hannah E Reses ◽  
Mark Fajans ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Asymptomatic Infection ◽  
Mitigation Strategies ◽  
Contact Tracing ◽  
Symptom Change ◽  
Household Contacts ◽  
Symptom Profiles ◽  
Asymptomatic Infections ◽  
Pcr Test ◽  
Over Time

Abstract Background Improved understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spectrum of disease is essential for clinical and public health interventions. There are limited data on mild or asymptomatic infections, but recognition of these individuals is key as they contribute to viral transmission. We describe the symptom profiles from individuals with mild or asymptomatic SARS-CoV-2 infection. Methods From 22 March to 22 April 2020 in Wisconsin and Utah, we enrolled and prospectively observed 198 household contacts exposed to SARS-CoV-2. We collected and tested nasopharyngeal specimens by real-time reverse-transcription polymerase chain reaction (rRT-PCR) 2 or more times during a 14-day period. Contacts completed daily symptom diaries. We characterized symptom profiles on the date of first positive rRT-PCR test and described progression of symptoms over time. Results We identified 47 contacts, median age 24 (3–75) years, with detectable SARS-CoV-2 by rRT-PCR. The most commonly reported symptoms on the day of first positive rRT-PCR test were upper respiratory (n = 32 [68%]) and neurologic (n = 30 [64%]); fever was not commonly reported (n = 9 [19%]). Eight (17%) individuals were asymptomatic at the date of first positive rRT-PCR collection; 2 (4%) had preceding symptoms that resolved and 6 (13%) subsequently developed symptoms. Children less frequently reported lower respiratory symptoms (21%, 60%, and 69% for &lt;18, 18–49, and ≥50 years of age, respectively; P = .03). Conclusions Household contacts with laboratory-confirmed SARS-CoV-2 infection reported mild symptoms. When assessed at a single timepoint, several contacts appeared to have asymptomatic infection; however, over time all developed symptoms. These findings are important to inform infection control, contact tracing, and community mitigation strategies.

EPIDEMIOLOGIC PROFILE OF THE INITIAL COVID 19 PATIENTS AT A DESIGNATED COVID HOSPITAL IN SOUTH TAMIL NADU

2021 ◽  
pp. 73-75
Author(s):  
John, Jebamalar ◽  
Manohar, Madhumitha ◽  
Kumaraswamy Uma Suresh Balan
Keyword(s):  
Tamil Nadu ◽  
Respiratory Illness ◽  
Transmission Probability ◽  
Asymptomatic Infection ◽  
Disease Spread ◽  
Contact Tracing ◽  
Surveillance Systems ◽  
Travel History ◽  
Epidemiologic Profile ◽  
Positive Contact

BACKGROUND:COVID-19, caused by SARS CoV-2 has caused a worldwide pandemic since its origins in December 2019. The spectrum of the disease ranges from asymptomatic infection to severe respiratory illness causing mortality in severe cases. Person to person spread through respiratory droplets appears to be the most common route of spread. AIM & OBJECTIVE:This study aims to assess the demographic prole of COVID-19 patients. In addition, measures of transmission probability are determined using travel history and contact tracing. SETTINGS AND DESIGN: This study was done at a Government medical college in South Tamil Nadu over four months among patients who were RT-PCR positive for SARS CoV-2. METHODS AND MATERIAL: Aquestionnaire from NCDC for COVID-19 patients was used for collecting demographic and clinical details. Travel history and contact tracing were obtained using telephonic interviews and in person interviews. STATISTICALANALYSIS USED: Data was entered using MS-Excel and analysed using R studio version 3.6.3. RESULTS: Majority of the patients belonged to 20 to 49 years of age. Around 14.6% were symptomatic with fever and sore throat being predominant. Diabetes and hypertension were the most associated comorbidities. A positive contact history was present among 46.58% of the cases. The secondary attack rate was 25.03% and R0 was 2.76 CONCLUSIONS: The absence of a positive contact history and the preponderance of asymptomatic cases seem to contribute to the spread of the disease and impede control efforts. Hence, a multi-pronged approach including community participation, active surveillance systems and legal measures would be of great impact in slowing disease spread.

scholarly journals Serosurveys for SARS-CoV-2: need of the hour

2020 ◽  
Vol 7 (10) ◽  
pp. 4209
Author(s):  
Siddharth Madan ◽  
Nisha Yadav ◽  
Maansi Sethi ◽  
Gunjan Rana ◽  
Akshi Sharma ◽  
...  
Keyword(s):  
Urban Areas ◽  
Point Of Care ◽  
Case Fatality ◽  
High Specificity ◽  
Asymptomatic Infection ◽  
Contact Tracing ◽  
Enzyme Linked Immunosorbent Assay ◽  
Institutional Settings ◽  
Overseas Operations ◽  
Bus Conductors

This letter is regarding tackling the highly infectious coronavirus disease (COVID-19).Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread across the globe, causing a worldwide pandemic. The total number of cases across the globe is about 11.6 million with over 5 lakh deaths. The number of individuals detected is always less than the actual number of infected, in nearly all respiratory viral pandemics. Rapid Point-of-Care Antigen detection test can detect SARS-CoV-2 early in the field setting. It has moderate sensitivity and high specificity yet limited availability. This test can be employed in the hospitals and containment zones and would aid in contact tracing, isolation of the affected individuals, localized containment and directing quarantine measures. IgG antibodies usually appear after one week of onset of infection and may last for several months. Serosurveys that detect these antibodies using Enzyme-linked immunosorbent assay (ELISA) help in the assessment of asymptomatic infection in close contacts, enhance the current understanding of the spread of disease, individual’s immune status and in identifying potential plasma donors. Case fatality rate is positively associated with SARS-CoV-2 seroprevalence as was demonstrated in the survey conducted in the Spanish population. Immuno-compromised patients, healthcare workers, relatively young working population comprising of bankers, media persons, individuals working at airports, overseas operations and industries, staff in municipal bodies, shopkeepers, vendors, courier services, telecommunication offices, drivers of hospital ambulances, hearse vans, buses, auto-rickshaw, taxies; bus conductors, farmers, electricity workers, migrant labourers who have travelled back from urban and peri-urban areas to rural/tribal; inhabitants of hard to reach areas, prisoners, densely populated regions of the country as well as natives after coming in contact with returned migrant; police and security personnel, those staying in institutional settings and hostels and inhabitants of containment zones should all be tested for the presence of antibodies against the virus.

Effect of coronavirus disease in patients with kidney disease in India

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 1255-1259
Author(s):  
Shashi Prabha Singh ◽  
Preeti Sharma ◽  
Durgesh singh ◽  
Pradeep kumar ◽  
Rakesh Sharma ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Clinical Trials ◽  
Kidney Disease ◽  
Meta Analysis ◽  
Tertiary Care ◽  
Type Ii Diabetes Mellitus ◽  
Asymptomatic Infection ◽  
Type Ii ◽  
Cardiorespiratory Failure ◽  
Inflammatory State

Coronavirus disease 19 is a global pandemic which infects over millions of people worldwide in a limited time and changes the lifestyle, clinical spectrum lies from asymptomatic infection to pneumonitis with cardiorespiratory failure and finally death. Higher mortality occurs in senior and who are suffering from co-morbidities like chronic kidney disease, (HTN) hypertension, (DM TYPE II) diabetes mellitus or (CVD) cardiovascular diseases. However, rather than normal individuals, patients with chronic kidney disease (CKD) are under higher risk for infections. The chronic systemic inflammatory state is a significant cause for morbidity and mortality in CKD patients. The objective of this review is to discuss the pathogenesis of COVID-19 in CKD, changes observed in the immune system of CKD patients, COVID-19 infections risk in CKD and therapeutic approach of COVID-19 in CKD patients. From the standpoint of frequent renal co-morbidities in covid19 patients, renal complications were explored in covid19 patients received at level 2 tertiary care Santosh Hospital, Ghaziabad, U.P. Delhi-NCR India during March to August 2020 as per the protocol of Nephrology Society of India. Relevant clinical trials were reviewed in support. Meta-analysis and clinical trials are covered in this review study. Duplicate studies are not taken into account. The outcome of the studies shows that CKD patients are more prone to COVID-19. CKD patients are more likely infected with COVID-19 virus. Whereas in intensive care, CKD occurs more frequent than DM type II and CVD. So,COVID-19 pathogenesis in CKD patients, risk of COVID-19, immunologic changes and therapy COVID-19 in CKD can add support in the effective management of COVID-19.

Can fake news really change behaviour? Evidence from a study of COVID-19 misinformation.

2020 ◽  
Author(s):  
Ciara Greene ◽  
Gillian Murphy
Keyword(s):  
Empirical Research ◽  
Health Behaviour ◽  
Real World ◽  
Empirical Data ◽  
Contact Tracing ◽  
Fake News ◽  
Behavioural Intentions ◽  
The Real ◽  
News Stories

Previous research has argued that fake news may have grave consequences for health behaviour, but surprisingly, no empirical data have been provided to support this assumption. This issue takes on new urgency in the context of the coronavirus pandemic. In this large preregistered study (N = 3746) we investigated the effect of exposure to fabricated news stories about COVID-19 on related behavioural intentions. We observed small but measurable effects on some related behavioural intentions but not others – for example, participants who read a story about problems with a forthcoming contact-tracing app reported reduced willingness to download the app. We found no effects of providing a general warning about the dangers of online misinformation on response to the fake stories, regardless of the framing of the warning in positive or negative terms. We conclude with a call for more empirical research on the real-world consequences of fake news.

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