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1.
PLoS One ; 16(4): e0249710, 2021.
Article in English | MEDLINE | ID: covidwho-1170007

ABSTRACT

BACKGROUND: Rapid antigen tests hold much promise for use in the school environment. However, the performance of these tests in non-clinical settings and among one of the main target populations in schools-asymptomatic children-is unclear. To address this gap, we examined the positive and negative concordance between the BinaxNOW™ rapid SARS-CoV-2 antigen assay and an RT-PCR test among children at a community-based Covid-19 testing site. METHODS: We conducted rapid antigen (BinaxNOW™) and oral fluid RT-PCR (Curative Labs) tests on children presenting at a walk-up testing site in Los Angeles County from November 25, 2020 to December 9, 2020. Positive concordance was determined as the fraction of RT-PCR positive participants that were also antigen positive. Negative concordance was determined as the fraction of RT-PCR negative participants that were also antigen negative. Multivariate logistic regression models were used to examine the association between positive or negative concordance and participant age, race-ethnicity, sex at birth, symptoms and Ct values. RESULTS: 226 children tested positive on RT-PCR; 127 children or 56.2% (95% CI: 49.5% to 62.8%) of these also tested positive on the rapid antigen test. Positive concordance was higher among symptomatic children (64.4%; 95% CI: 53.4% to 74.4%) compared to asymptomatic children (51.1%; 95% CI: 42.5% to 59.7%). Positive concordance was negatively associated with Ct values and was 93.8% (95% CI: 69.8% to 99.8%) for children with Ct values less than or equal to 25. 548 children tested negative on RT-PCR; 539 or 98.4% (95% CI: 96.9% to 99.2%) of these also tested negative on the rapid antigen test. Negative concordance was higher among asymptomatic children. CONCLUSIONS: Rapid antigen testing can successfully identify most COVID infections in children with viral load levels likely to be infectious. Serial rapid testing may help compensate for limited sensitivity in early infection.


Subject(s)
Antigens, Viral/analysis , /diagnosis , Mass Screening/methods , Adolescent , /methods , Child , Child, Preschool , Female , Humans , Los Angeles/epidemiology , Male , Schools , Sensitivity and Specificity , Viral Load/methods
2.
Front Public Health ; 9: 640009, 2021.
Article in English | MEDLINE | ID: covidwho-1154264

ABSTRACT

A simple, common-sense, three-component procedure-the Carrier Separation Plan (CSP)-can immediately halt the transmission of SARS-CoV-2 or a comparable pathogen, allow the safe reopening of an entire economy without the need for social distancing, and quickly eradicate the pathogen from the population (assuming the pathogen can be killed by the immune systems of the carriers). The three components are (a) nearly simultaneous self-testing for the pathogen by an entire population, followed rapidly by (b) nearly simultaneous self-isolation of carriers, and (c) secondary screening at entrances to facilities where people congregate. After a period of preparation lasting roughly 5-10 weeks, these steps could and probably should be taken in a single day. The power of this methodology has already been demonstrated in varying degrees with groups ranging in size from 1,000 to 11 million. Although this plan might seem daunting, its costs are minimal compared to the losses we have incurred by relying on half measures, and the US and other countries have the technological, logistical, and industrial capacities to implement this plan in a matter of weeks. With proper messaging during the weeks leading up to the testing, compliance in such a program is likely to be high given the potential benefits, and because participation is voluntary and testing is noninvasive, the legal and ethical issues associated with such a program are minimal - trivial, in fact, compared to those associated with imposing a months-long lockdown on an entire population. A SIRD/CSP model suggests that the single-day testing and separation procedure will substantially lower the number of infections, even if compliance with the procedure is modest. Modeling also suggests that when long-term secondary screening is added to the 1-day procedure, over time, the pathogen is eradicated from the population. This can occur even when compliance with secondary screening is itself relatively low.


Subject(s)
/prevention & control , Communicable Disease Control/methods , Diagnostic Techniques and Procedures/standards , Mass Screening/methods , Population Surveillance/methods , Public Health/standards , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Models, Theoretical , Practice Guidelines as Topic
3.
J Occup Environ Med ; 63(4): e184-e186, 2021 Apr 01.
Article in English | MEDLINE | ID: covidwho-1153280

ABSTRACT

OBJECTIVE: To evaluate an empirical olfactory test to identify COVID-19 cases during a workplace entrance screening. METHOD: An active screening for olfactory dysfunction using water and vinegar was conducted in April to June 2020 among 4120 meat packing workers in Latin America. RESULTS: The sensitivity and specificity of the active olfactory screening examination were 41.2% and 85.3%, respectively, using reverse transcription polymerase chain reaction (RT-PCR) tests as a gold standard. 10.6% of employees who tested positive for COVID-19 had an olfactory dysfunction as their only symptom. These individuals would not have been identified with standard workplace screening measures including temperature screening. CONCLUSION: Active screening for olfactory dysfunction may serve as a valuable tool to both identify potential COVID-19 infections and exclude those who do not have infection and should be a part of parallel algorithm combined with standard workplace entrance screening procedures.


Subject(s)
/diagnosis , Mass Screening/methods , Workplace , Acetic Acid , /physiopathology , Humans , Mass Screening/standards , Meat-Packing Industry , Sensitivity and Specificity , Water
5.
JAMA Netw Open ; 4(3): e211974, 2021 03 01.
Article in English | MEDLINE | ID: covidwho-1148765

ABSTRACT

Importance: Breast cancer screening, surveillance, and diagnostic imaging services were profoundly limited during the initial phase of the coronavirus disease 2019 (COVID-19) pandemic. Objective: To develop a risk-based strategy for triaging mammograms during periods of decreased capacity. Design, Setting, and Participants: This population-based cohort study used data collected prospectively from mammography examinations performed in 2014 to 2019 at 92 radiology facilities in the Breast Cancer Surveillance Consortium. Participants included individuals undergoing mammography. Data were analyzed from August 10 to November 3, 2020. Exposures: Clinical indication for screening, breast symptoms, personal history of breast cancer, age, time since last mammogram/screening interval, family history of breast cancer, breast density, and history of high-risk breast lesion. Main Outcomes and Measures: Combinations of clinical indication, clinical history, and breast cancer risk factors that subdivided mammograms into risk groups according to their cancer detection rate were identified using classification and regression trees. Results: The cohort included 898 415 individuals contributing 1 878 924 mammograms (mean [SD] age at mammogram, 58.6 [11.2] years) interpreted by 448 radiologists, with 1 722 820 mammograms in individuals without a personal history of breast cancer and 156 104 mammograms in individuals with a history of breast cancer. Most individuals were aged 50 to 69 years at imaging (1 113 174 mammograms [59.2%]), and 204 305 (11.2%) were Black, 206 087 (11.3%) were Asian or Pacific Islander, 126 677 (7.0%) were Hispanic or Latina, and 40 021 (2.2%) were another race/ethnicity or mixed race/ethnicity. Cancer detection rates varied widely based on clinical indication, breast symptoms, personal history of breast cancer, and age. The 12% of mammograms with very high (89.6 [95% CI, 82.3-97.5] to 122.3 [95% CI, 108.1-138.0] cancers detected per 1000 mammograms) or high (36.1 [95% CI, 33.1-39.3] to 47.5 [95% CI, 42.4-53.3] cancers detected per 1000 mammograms) cancer detection rates accounted for 55% of all detected cancers and included mammograms to evaluate an abnormal mammogram or breast lump in individuals of all ages regardless of breast cancer history, to evaluate breast symptoms other than lump in individuals with a breast cancer history or without a history but aged 60 years or older, and for short-interval follow-up in individuals aged 60 years or older without a breast cancer history. The 44.2% of mammograms with very low cancer detection rates accounted for 13.1% of detected cancers and included annual screening mammograms in individuals aged 50 to 69 years (3.8 [95% CI, 3.5-4.1] cancers detected per 1000 mammograms) and all screening mammograms in individuals younger than 50 years regardless of screening interval (2.8 [95% CI, 2.6-3.1] cancers detected per 1000 mammograms). Conclusions and Relevance: In this population-based cohort study, clinical indication and individual risk factors were associated with cancer detection and may be useful for prioritizing mammography in times and settings of decreased capacity.


Subject(s)
Breast Neoplasms/diagnosis , Health Care Rationing/methods , Mammography , Mass Screening/methods , Pandemics , Triage/methods , Aged , Breast/diagnostic imaging , Breast/pathology , Cohort Studies , Early Detection of Cancer , Female , Humans , Medical History Taking , Middle Aged , Physical Examination , Radiology , Risk Factors
7.
PLoS Comput Biol ; 17(3): e1008688, 2021 03.
Article in English | MEDLINE | ID: covidwho-1125385

ABSTRACT

Outbreaks of SARS-CoV-2 are threatening the health care systems of several countries around the world. The initial control of SARS-CoV-2 epidemics relied on non-pharmaceutical interventions, such as social distancing, teleworking, mouth masks and contact tracing. However, as pre-symptomatic transmission remains an important driver of the epidemic, contact tracing efforts struggle to fully control SARS-CoV-2 epidemics. Therefore, in this work, we investigate to what extent the use of universal testing, i.e., an approach in which we screen the entire population, can be utilized to mitigate this epidemic. To this end, we rely on PCR test pooling of individuals that belong to the same households, to allow for a universal testing procedure that is feasible with the limited testing capacity. We evaluate two isolation strategies: on the one hand pool isolation, where we isolate all individuals that belong to a positive PCR test pool, and on the other hand individual isolation, where we determine which of the individuals that belong to the positive PCR pool are positive, through an additional testing step. We evaluate this universal testing approach in the STRIDE individual-based epidemiological model in the context of the Belgian COVID-19 epidemic. As the organisation of universal testing will be challenging, we discuss the different aspects related to sample extraction and PCR testing, to demonstrate the feasibility of universal testing when a decentralized testing approach is used. We show through simulation, that weekly universal testing is able to control the epidemic, even when many of the contact reductions are relieved. Finally, our model shows that the use of universal testing in combination with stringent contact reductions could be considered as a strategy to eradicate the virus.


Subject(s)
/methods , /prevention & control , Epidemics/prevention & control , Belgium/epidemiology , /statistics & numerical data , Computational Biology , Computer Simulation , Contact Tracing/methods , Contact Tracing/statistics & numerical data , Contact Tracing/trends , False Negative Reactions , Family Characteristics , Feasibility Studies , Humans , Mass Screening/methods , Mass Screening/statistics & numerical data , Mass Screening/trends , Models, Statistical , Quarantine/methods , Quarantine/statistics & numerical data , Quarantine/trends , Travel
8.
BMC Infect Dis ; 21(1): 243, 2021 Mar 05.
Article in English | MEDLINE | ID: covidwho-1119415

ABSTRACT

BACKGROUND: Sniffer dogs are able to detect certain chemical particles and are suggest to be capable of helping diagnose some medical conditions and complications, such as colorectal cancer, melanoma, bladder cancer, and even critical states such as hypoglycemia in diabetic patients. With the global spread of COVID-19 throughout the world and the need to have a real-time screening of the population, especially in crowded places, this study aimed to investigate the applicability of sniffer dogs to carry out such a task. METHODS: Firstly, three male and female dogs from German shepherd (Saray), German black (Kuzhi) and Labrador (Marco) breeds had been intensively trained throughout the classical conditioning method for 7 weeks. They were introduced to human specimens obtained from the throat and pharyngeal secretions of participants who were already reported positive or negative for SARS-COV-2 infection be RT-PCR. Each dog underwent the conditioning process for almost 1000 times. In the meantime another similar condition process was conducted on clothes and masks of COVID-19 patient using another three male and female dogs from Labrador (Lexi), Border gypsy (Sami), and Golden retriever (Zhico) breeds. In verification test for the first three dogs, 80 pharyngeal secretion samples consisting of 26 positive and 54 negative samples from different medical centers who underwent RT-PCR test were in a single-blind method. In the second verification test for the other three dogs, masks and clothes of 50 RT-PCR positive and 70 RT-PCR negative cases from different medical center were used. RESULTS: In verification test using pharyngeal secretion, the sniffer dogs' detection capability was associated with a 65% of sensitivity and 89% of specificity and they amanged to identify 17 out of the 26 positive and 48 out of the 54 true negative samples. In the next verification test using patients' face masks and clothes, 43 out of the 50 positive samples were correctly identified by the dogs. Moreover, out of the 70 negative samples, 65 samples were correctly found to be negative. The sensitivity of this test was as high as 86% and its specificity was 92.9%. In addition, the positive and negative predictive values were 89.6 and 90.3%, respectively. CONCLUSION: Dogs are capable of being trained to identify COVID-19 cases by sniffing their odour, so they can be used as a reliable tool in limited screening.


Subject(s)
/methods , Mass Screening/methods , Animals , /epidemiology , Dogs , Female , Humans , Iran/epidemiology , Male , Predictive Value of Tests , Proof of Concept Study , /physiology , Sensitivity and Specificity , Single-Blind Method
9.
PLoS One ; 16(3): e0247995, 2021.
Article in English | MEDLINE | ID: covidwho-1115307

ABSTRACT

BACKGROUND: Primary care is the major point of access in most health systems in developed countries and therefore for the detection of coronavirus disease 2019 (COVID-19) cases. The quality of its IT systems, together with access to the results of mass screening with Polymerase chain reaction (PCR) tests, makes it possible to analyse the impact of various concurrent factors on the likelihood of contracting the disease. METHODS AND FINDINGS: Through data mining techniques with the sociodemographic and clinical variables recorded in patient's medical histories, a decision tree-based logistic regression model has been proposed which analyses the significance of demographic and clinical variables in the probability of having a positive PCR in a sample of 7,314 individuals treated in the Primary Care service of the public health system of Catalonia. The statistical approach to decision tree modelling allows 66.2% of diagnoses of infection by COVID-19 to be classified with a sensitivity of 64.3% and a specificity of 62.5%, with prior contact with a positive case being the primary predictor variable. CONCLUSIONS: The use of a classification tree model may be useful in screening for COVID-19 infection. Contact detection is the most reliable variable for detecting Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases. The model would support that, beyond a symptomatic diagnosis, the best way to detect cases would be to engage in contact tracing.


Subject(s)
/diagnosis , Disease Transmission, Infectious/statistics & numerical data , Adult , Aged , Cohort Studies , Contact Tracing , Data Mining/methods , Decision Trees , Female , Humans , Male , Mass Screening/methods , Middle Aged , Probability , Retrospective Studies , Sensitivity and Specificity
11.
PLoS One ; 16(2): e0247767, 2021.
Article in English | MEDLINE | ID: covidwho-1105822

ABSTRACT

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has revealed the global public health importance of robust diagnostic testing. To overcome the challenge of nucleic acid (NA) extraction and testing kit availability, an efficient method is urgently needed. OBJECTIVES: To establish an efficient, time and resource-saving and cost-effective methods, and to propose an ad hoc pooling approach for mass screening of SARS-CoV-2. METHODS: We evaluated pooling approach on both direct clinical and NA samples. The standard reverse transcriptase polymerase chain reaction (RT-PCR) test of the SARS CoV-2 was employed targeting the nucleocapsid (N) and open reading frame (ORF1ab) genomic region of the virus. The experimental pools were created using SARS CoV-2 positive clinical samples and extracted RNA spiked with up to 9 negative samples. For the direct clinical samples viral NA was extracted from each pool to a final extraction volume of 200µL, and subsequently both samples tested using the SARS CoV-2 RT-PCR assay. RESULTS: We found that a single positive sample can be amplified and detected in pools of up to 7 samples depending on the cycle threshold (Ct) value of the original sample, corresponding to high, and low SARS CoV-2 viral copies per reaction. However, to minimize false negativity of the assay with pooling strategies and with unknown false negativity rate of the assay under validation, we recommend pooling of 4/5 in 1 using the standard protocols of the assay, reagents and equipment. The predictive algorithm indicated a pooling ratio of 5 in 1 was expected to retain accuracy of the test irrespective of the Ct value samples spiked, and result in a 137% increase in testing efficiency. CONCLUSIONS: The approaches showed its concept in easily customized and resource-saving manner and would allow expanding of current screening capacities and enable the expansion of detection in the community. We recommend clinical sample pooling of 4 or 5 in 1. However, we don't advise pooling of clinical samples when disease prevalence is greater than 7%; particularly when sample size is large.


Subject(s)
/methods , RNA, Viral/isolation & purification , /isolation & purification , Algorithms , /economics , Humans , Mass Screening/economics , Mass Screening/methods , RNA, Viral/genetics , Sensitivity and Specificity , Specimen Handling/economics , Specimen Handling/methods
12.
Antimicrob Resist Infect Control ; 10(1): 44, 2021 02 27.
Article in English | MEDLINE | ID: covidwho-1105744

ABSTRACT

The proportion of asymptomatic carriers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains elusive and the potential benefit of systematic screening during the SARS-CoV-2-pandemic is controversial. We investigated the proportion of asymptomatic inpatients who were identified by systematic screening for SARS-CoV-2 upon hospital admission. Our analysis revealed that systematic screening of asymptomatic inpatients detects a low total number of SARS-CoV-2 infections (0.1%), questioning the cost-benefit ratio of this intervention. Even when the population-wide prevalence was low, the proportion of asymptomatic carriers remained stable, supporting the need for universal infection prevention and control strategies to avoid onward transmission by undetected SARS-CoV-2-carriers during the pandemic.


Subject(s)
Asymptomatic Infections/epidemiology , /isolation & purification , Aged , /transmission , /methods , Cost-Benefit Analysis , Female , Humans , Male , Mass Screening/economics , Mass Screening/methods , Middle Aged , Switzerland/epidemiology
13.
Pan Afr Med J ; 35(Suppl 2): 93, 2020.
Article in English | MEDLINE | ID: covidwho-1100422

ABSTRACT

Introduction: The COVID-19 pandemic presents an opportunity for the Nigerian health system to harness the potentials available in the private sector to augment the capacity within the public health system. This survey was carried out to assess private facility readiness in providing screening services in Edo State. Methods: This was a descriptive cross-sectional study carried out among private facilities in Edo state. Facilities were selected using stratified sampling technique. Data was collected using adapted questionnaires and an observational checklist. Facility readiness was assessed using the Nigeria Centre for Disease Control recommendations for screening. Parameters were scored and overall scores were converted to proportions. Facilities that scored 70% and above were adjudged to be ready while facilities that scored 69% and below were adjudged to be not ready. Results: A total of 252 health facilities were assessed, comprising 149 (59.1%) hospitals/clinics, 62 (24.6%) pharmacies and 41 (16.3%) laboratories. One hundred and forty-two (95.3%), 60 (96.8%) and 41 (100.0%) hospitals/clinics, pharmacies and laboratories, respectively had hand hygiene facilities. However, overall facility readiness assessment scores for screening services were low with only 51 (34.2%) hospitals/clinics, 2 (3.2%) pharmacies and 2 (4.9%) laboratories achieving high enough scores to be adjudged ready for screening services. Conclusion: Overall facility readiness of the private health sector to provide screening services in Edo State was assessed to be low. The government and facility owners will need to ensure that screening services are improved in all facilities to help mitigate community spread of COVID-19.


Subject(s)
/methods , Delivery of Health Care/organization & administration , Mass Screening/methods , Cross-Sectional Studies , Health Facilities , Humans , Nigeria , Pandemics , Private Facilities/organization & administration , Private Sector , Surveys and Questionnaires
14.
Pan Afr Med J ; 35(Suppl 2): 37, 2020.
Article in English | MEDLINE | ID: covidwho-1100367

ABSTRACT

Le monde entier est touché par un bouleversement sans précédent, crée par un virus incontrôlable et qui a pris le pas sur les théories scientifiques les plus élaborées. Les grandes puissances peinent à empêcher l'hécatombe dans les effectifs de leurs citoyens infectés, en dépit de toutes les avancées scientifiques et technologiques. Les pays à ressources limitées et dans lesquels vivent des populations parmi les plus vulnérables apparaissent comme les cibles sur lesquelles le virus est susceptible de faire le maximum de dégâts. Cette note discute des approches stratégiques, propose des mesures politiques et suggère des recommandations. La capacité de dépistage/diagnostic, les mesures de protection et d'assainissement, la communication et l'implication de la communauté seraient des priorités de riposte.


Subject(s)
/epidemiology , Mass Screening/methods , Vulnerable Populations , Burkina Faso , Developing Countries , Humans
15.
Medicina (Kaunas) ; 57(2)2021 Feb 23.
Article in English | MEDLINE | ID: covidwho-1100137

ABSTRACT

The global pandemic of the coronavirus disease 2019 is a known consequence of infection of severe respiratory syndrome coronavirus-2 (SARS-CoV-2). It has affected nations worldwide with soaring number of cases daily. Symptoms such as fever, cough, and shortness of breath, diarrhea, nausea and vomiting are commonly presented in COVID-19 patients. This focused review aims to discuss these uncommon and atypical COVID-19 symptoms that may be presented which might affect neurological, cardiovascular, cutaneous and ocular systems and their possible mode of actions. Nonetheless, there are some cases of reported uncommon or atypical symptoms which may warrant healthcare professionals to be aware of, especially when in contact with patients. The knowledge and information concerning these symptoms might be able to provide additional cues for healthcare professional by subjecting patients to COVID-19 screening. Meanwhile, it might be able to further enhance the alertness and additional precautions being taken by healthcare personnel, which eventually lead to reduced risk of infections.


Subject(s)
/methods , Mass Screening/methods , Symptom Assessment/methods , Humans
16.
J Am Board Fam Med ; 34(Suppl): S55-S60, 2021 Feb.
Article in English | MEDLINE | ID: covidwho-1100005

ABSTRACT

BACKGROUND: The COVID-19 (C-19) pandemic required swift response from health care organizations to mitigate spread and impact. A large integrated health network rapidly deployed and operationalized multiple access channels to the community, allowing assessment and triage to occur virtually. These channels were characterized by swift implementation of virtual models, including asynchronous e-visits and video visits for C-19 screening. PURPOSE: (1) Evaluate implementation characteristics of C-19 screening e-visits and video visits. (2) Identify volume of C-19 screening and other care provided via e-visits and video visits. (3) Discuss future implications of expanded virtual access models. METHODS: Retrospective analysis of implementation data for C-19 screening e-visits and video visits, including operational characteristics and visit/screening volumes conducted. RESULTS: Virtual channels were implemented and rapidly expanded during the first week C-19 testing was made available. During the study period, primary care clinicians conducted 10,673 e-visits and 31,226 video visits with 9,126 and 26,009 patients, respectively. Within these 2 virtual modalities, 4,267 C-19 tests were ordered (10% of visits). Four hundred forty-eight clinicians supported 24/7 access to these virtual modalities. DISCUSSION: Given ongoing patient interest and opportunity, virtual health care services will continue to be available for an expanded number of symptoms and diagnoses.


Subject(s)
Capacity Building/organization & administration , Delivery of Health Care, Integrated/methods , Telemedicine/methods , /epidemiology , Humans , Mass Screening/methods , Pandemics , Primary Health Care/organization & administration , Retrospective Studies
17.
PLoS One ; 16(2): e0246513, 2021.
Article in English | MEDLINE | ID: covidwho-1099923

ABSTRACT

Castiglione D'Adda is one of the municipalities more precociously and severely affected by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) epidemic in Lombardy. With our study we aimed to understand the diffusion of the infection by mass serological screening. We searched for SARS-CoV-2 IgGs in the entire population on a voluntary basis using lateral flow immunochromatographic tests (RICT) on capillary blood (rapid tests). We then performed chemioluminescent serological assays (CLIA) and naso-pharyngeal swabs (NPS) in a randomized representative sample and in each subject with a positive rapid test. Factors associated with RICT IgG positivity were assessed by uni- and multivariate logistic regression models. Out of the 4143 participants, 918 (22·2%) showed RICT IgG positivity. In multivariable analysis, IgG positivity increases with age, with a significant non-linear effect (p = 0·0404). We found 22 positive NPSs out of the 1330 performed. Albeit relevant, the IgG prevalence is lower than expected and suggests that a large part of the population remains susceptible to the infection. The observed differences in prevalence might reflect a different infection susceptibility by age group. A limited persistence of active infections could be found after several weeks after the epidemic peak in the area.


Subject(s)
/methods , /transmission , Antibodies, Viral/blood , /diagnosis , Cross-Sectional Studies , Female , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Italy/epidemiology , Male , Mass Screening/methods , Prevalence , /pathogenicity
18.
Pan Afr Med J ; 35(Suppl 2): 84, 2020.
Article in English | MEDLINE | ID: covidwho-1094378

ABSTRACT

Confirmation of COVID-19 infection is still challenging in Cameroon due to lack of sufficient RT-PCR tests and screening capacity. International organizations as well as philanthropic donators initially provided these tests. Due to limited kits availability, mass screening is currently a luxury that the country cannot afford. This impacts on estimates of disease prevalence, on the understanding of its burden and delays the implementation of targeted preventive measures. Besides RT-PCR, chest CT-scan could be a useful tool for screening purposes. However, its sensitivity and cost make its integration in management algorithms difficult. We discuss below the challenges and potential solutions that could ease the diagnosis of COVID-19 infection in Cameroon.


Subject(s)
/diagnosis , Mass Screening/methods , Cameroon , Humans , Sensitivity and Specificity , Tomography, X-Ray Computed
19.
BMC Med ; 19(1): 50, 2021 02 17.
Article in English | MEDLINE | ID: covidwho-1088595

ABSTRACT

BACKGROUND: Following implementation of strong containment measures, several countries and regions have low detectable community transmission of COVID-19. We developed an efficient, rapid, and scalable surveillance strategy to detect remaining COVID-19 community cases through exhaustive identification of every active transmission chain. We identified measures to enable early detection and effective management of any reintroduction of transmission once containment measures are lifted to ensure strong containment measures do not require reinstatement. METHODS: We compared efficiency and sensitivity to detect community transmission chains through testing of the following: hospital cases; fever, cough and/or ARI testing at community/primary care; and asymptomatic testing; using surveillance evaluation methods and mathematical modelling, varying testing capacities, reproductive number (R) and weekly cumulative incidence of COVID-19 and non-COVID-19 respiratory symptoms using data from Australia. We assessed system requirements to identify all transmission chains and follow up all cases and primary contacts within each chain, per million population. RESULTS: Assuming 20% of cases are asymptomatic and 30% of symptomatic COVID-19 cases present for testing, with R = 2.2, a median of 14 unrecognised community cases (8 infectious) occur when a transmission chain is identified through hospital surveillance versus 7 unrecognised cases (4 infectious) through community-based surveillance. The 7 unrecognised community upstream cases are estimated to generate a further 55-77 primary contacts requiring follow-up. The unrecognised community cases rise to 10 if 50% of cases are asymptomatic. Screening asymptomatic community members cannot exhaustively identify all cases under any of the scenarios assessed. The most important determinant of testing requirements for symptomatic screening is levels of non-COVID-19 respiratory illness. If 4% of the community have respiratory symptoms, and 1% of those with symptoms have COVID-19, exhaustive symptomatic screening requires approximately 11,600 tests/million population using 1/4 pooling, with 98% of cases detected (2% missed), given 99.9% sensitivity. Even with a drop in sensitivity to 70%, pooling was more effective at detecting cases than individual testing under all scenarios examined. CONCLUSIONS: Screening all acute respiratory disease in the community, in combination with exhaustive and meticulous case and contact identification and management, enables appropriate early detection and elimination of COVID-19 community transmission. An important component is identification, testing, and management of all contacts, including upstream contacts (i.e. potential sources of infection for identified cases, and their related transmission chains). Pooling allows increased case detection when testing capacity is limited, even given reduced test sensitivity. Critical to the effectiveness of all aspects of surveillance is appropriate community engagement, messaging to optimise testing uptake and compliance with other measures.


Subject(s)
/epidemiology , Independent Living/trends , Models, Theoretical , Population Surveillance/methods , Australia/epidemiology , Basic Reproduction Number/prevention & control , Early Diagnosis , Feasibility Studies , Hospitalization/trends , Humans , Longitudinal Studies , Mass Screening/methods , Mass Screening/trends
20.
J Clin Virol ; 136: 104764, 2021 03.
Article in English | MEDLINE | ID: covidwho-1085530

ABSTRACT

The current scale of public and private testing cannot be expected to meet the emerging need for higher levels of community-level and repeated screening of asymptomatic Canadians for SARS-CoV-2. Rapid point-of-care techniques are increasingly being offered to fill the gap in screening levels required to identify undiagnosed individuals with high viral loads. However, rapid, point-of-care tests often have lower sensitivity in practice. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) for SARS-CoV-2 has proven sensitive and specific and provides visual results in minutes. Using a commercially available kit for RT-LAMP and primer set targetting nucleocapsid (N), we tested a blinded set of 101 archived nasopharyngeal (NP) swab samples with known RT-PCR results. RT-LAMP reactions were incubated at 65 °C for 30 min, using heat-inactivated nasopharyngeal swab sample in viral transport medium, diluted tenfold in water, as input. RT-LAMP agreed with all RT-PCR defined negatives (N = 51), and all positives with cycle threshold (Ct) less than 20 (N = 24), 65% of positives with Ct between 20-30 (N = 17), and no positives with Ct greater than 30 (N = 9). RT-LAMP requires fewer and different core components, so may not compete directly with the mainline testing workflow, preserving precious central laboratory resources for those with the greatest need. Careful messaging must be provided when using less-sensitive tests, so that people are not falsely reassured by negative results, but this caveat must be weighed against the clear benefits of reliably identifying those with high levels of virus in prioritized samples at the point of care.


Subject(s)
/methods , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , Point-of-Care Testing , Reverse Transcriptase Polymerase Chain Reaction/methods , Asymptomatic Diseases , Canada , Humans , Mass Screening/methods , Nasopharynx/virology , RNA, Viral/analysis , Sensitivity and Specificity
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