· Studies suggest that antigen-based rapid diagnostic tests (Ag-RDTs) can be used in a population level with high prevalence of COVID-19 disease where health systems are overwhelmed or where nucleic acid amplification tests (NAATs) such as real time reverse transcription polymerase chain reaction (rRT-PCR) are not available.
· The Canadian COVID-19 Testing and Screening Expert Advisory Panel recommends the use of frequent screening with rapid diagnostic tests in selected groups to limit outbreaks.
· WHO and European Center for Disease Prevention and Control recommend using Ag-RDTs with high sensitivity and specificity when NAATs are not available or turnaround time negatively affects NAATs’ clinical utility. For example, COVID-19 Ag-RDTs can be used to surveil health care workers or residents of congregate dwellings during outbreaks or when community transmission rates are high, to screen at-risk individuals to support outbreak investigations, or to screen suspected COVID-19 outbreaks in early stages in settings where NAATs are not available.
· WHO does not recommend Ag-RDTs usage when expected prevalence is low (e.g., screening at points of entry) unless an Ag-RDT’s specificity is high (>99%).
· Studies have shown that Panbio™ COVID-19 Ag Test (Abbott) can have overall sensitivity of 72.6% to 95.2% and specificity of 98.0% to 100% and suggest that this test is appropriate for contagious case identification and asymptomatic case screening, especially in high prevalence (>5%) settings.
· WHO recommends that iterative Ag-RDT testing or confirmatory rRT-PCR testing be done in symptomatic patients or asymptomatic contacts of COVID-19 cases since a negative Ag-RDT result cannot completely exclude an active COVID-19 infection.
· Challenges of population level testing (whether they succeed or fail) such as required logistics and resources (e.g., immunizers, access to Ag-RDTs and equipment), performance accuracy of Ag-RDTs (e.g., false positive or negative rates in real world settings), and public trust and engagement in testing and future measures (e.g., vaccine uptake) are yet to be considered.
An optimal surveillance strategy for COVID-19 infection in healthcare workers (HCWs) has yet to be determined.
Weekly screening of HCWs for infection through polymerase chain reaction (PCR) testing would reduce their contribution to SARS-CoV-2 transmission by approximately one quarter.
Any testing surveillance strategy should be in addition to other strategies already in place to identify symptomatic HCW.
Any strategy needs to take into consideration the availability of testing (i.e. feasibility) and the level of community transmission (i.e. the risk of asymptomatic HCWs entering the facility and spreading the virus).
HCWs could be categorized as high, medium, or low risk based upon their exposure to COVID-19 and the frequency of surveillance could be designed accordingly.
Newaz, S; Lee, S; Reeder, B; Groot, G; Young, C; Fox, L. What surveillance strategy is most effective for COVID-19 testing in healthcare workers? 2020 Nov 10; Document no.: EOC110401 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 26 p. (CEST rapid review report)
The evidence for alternative active monitoring schedules for confirmed cases of COVID-19 and their cases is limited
The prevailing consensus is that confirmed cases of COVID-19 and their high-risk close contacts should undergo active daily monitoring
When public health resources are limited, active monitoring programs should consider prioritizing vulnerable populations, incorporating passive monitoring practices and adopting virtual monitoring platforms
McLean, M; Groot, G; Dalidowicz, M; Miller, L. Are less frequent (than daily) follow-up/monitoring used in COVID or other communicable diseases? 2020 Oct 6; Document no.:PH092301 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 31 p. (CEST rapid review report)
· The significance of rhinorrhea as a presenting/predictive clinical feature of COVID-19 is unclear at this time with rates ranging from as low as 2% to as high as 60% in the published literature
· Rhinorrhea generally associated with less severe disease
· No reports of sneezing as a clinical symptom of COVID-19
Badea, A; Groot, G; Howell-Spooner, B; Young, C. What is the evidence that runny nose or sneezing are symptoms of COVID-19? 2020 Sep 29; Document no.: EOC092401 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 16 p. (CEST rapid review report)
· Temperature screening has not yet been demonstrated to reduce COVID-19 spread or accurately identify COVID-19 cases in schools. This did not prove to be a useful strategy when implemented in Singapore during the 2003 SARS epidemic.
· 14% to 19% of children with COVID-19 have an asymptomatic presentation and fever only develops in less than half of symptomatic pediatric cases. Fever is also a common presentation of childhood illnesses unrelated to COVID-19.
· Chemical and plastic-strip thermometers are considered unreliable in pediatric clinical settings and there is also an element of user error with any thermometer type.
Radu, L; Groot, G; Badea, A; Mueller, M; Young, C. Is the use of thermometers an effective screening strategy for students in schools during COVID-19? 2020 Sep 4; Document no.: EOC090201 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 13 p. (CEST rapid review report)
· Infrared thermometers detect the infrared waves emitted by an object and convert into an electrical signal to display the distribution of temperature
· Infrared thermometers do not emit radiation, however many are equipped with a laser tracker beam, similar to that found in television remote controls
· The Pineal Gland is located deep inside the brain, separated from the forehead by the presence of the skull and several centimeters of brain tissue
Badea, A; Groot, G; Ellsworth, C; Fox, L. Is there evidence of risks for using infrared thermometers? 2020 Aug 29; Document no.: EOC082502 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 12 p. (CEST rapid review report)
· The CDC does not recommend universal symptom screening (all students in K-12 grades) to be done by schools prior to entry
· Schools/districts should individually work with public health officials to determine the necessity and details of implementing any testing strategies
· European CDC recommends that all symptomatic individuals and asymptomatic high-risk close contacts should be referred for testing – fast and effective contact tracing following testing is key
· Large scale universal testing in school settings has not been studied and it’s efficacy compared to implementation of other infection prevention control measures is unknown
· Large scale testing in school settings to date has largely been done in response to an outbreak, not as routine surveillance
Badea, A; Muhajarine, N; Howell-Spooner, B; Mueller, M. What laboratory surveillance testing strategies are effective for COVID-19 in school settings? 2020 Aug 27; Document no.: PH082501 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 23 p. (CEST rapid review report)
Signs and symptoms of COVID-19 are categorized as constitutional, respiratory, gastrointestinal, neurological, laboratory, imaging, and other.
Constitutional signs and symptoms include fever (Median=80% prevalence on cross-sectional retrospective chart reviews; range 30-98%), fatigue (M=41%; range 8-81%), myalgia or arthralgia (M=31%; range 5-63%), headache (M=9%; range 6-70%), sore throat (M=19%; range 11-53%), weight loss (M=31%; 23-50%), and hypotension (31%; Aggarwal et al., 2020).
Respiratory symptoms include cough (M=63%; range 33-88%), nasal congestion (M=41%; range 14-68%), rhinorrhea (M=7%; range 5-60%), dyspnea (M=53%; range 5-88%), phlegm (M=28%; range 18-40%), hemoptysis (5%; Xu et al., 2020) and chest tightness (M=40%; range 23-64%).
Gastrointestinal (GI) signs and symptoms include nausea and vomiting (M=14%; range 2-22%), diarrhea (M=18%; range 3-35%), and low appetite (M=21%; range 12-63%).
Approximately 36% of COVID-19+ patients present with neurological signs and symptoms which may include delirium, confusion, hallucinations, dizziness, seizure, or loss of senses of smell or taste. Presence of neurological findings is indicative of a worse outcome (Chen et al. 2020).
Abnormal laboratory findings are more common in older patients (Chen et al., 2020) and may include elevated C-reactive protein and erythrocyte sedimentation rate, lymphopenia, elevated D-dimer, leukopenia, elevated lactate dehydrogenase, lower white blood cell count, lower oxygen saturation (=94% or supplemental oxygen required), and hyponatremia (Duan et al., 2020; Ihle-Hansen, et al.2020; Xu et al., 2020; Fu et al., 2020).
The majority of COVID-19 + patients have abnormal imaging findings including multiple mottling and ground glass opacities (GGO) on chest CT scan. Bilateral pneumonia is present in between 73-98% of adults in critical care (Fu et al., 2020; Du et al., 2020).
Other signs and symptoms observed in LTC home residents with dementia include increased falls, change in behavior from the previous shift, more unsettled, and increased wandering (Ihle-Hansen et al., 2020).
The majority of patients (63%) of all ages present with symptoms that have lasted between 4 and 7 days (Buckner et al. 2020; Ihle-Hansen et al., 2020; Lin et al., 2020).
See Table 2 for a summary of infrequent (<10%), frequent (20-50%), and very frequent (>60%)clinical manifestations, laboratory test abnormalities and radiographic findings from a paper by Bonanad et al. 2020.
Screening and Testing Considerations:
Although 90.5% of COVID-19 + patients of all ages present with cough, fever, and/or breathlessness (Baker et al., 2020), screening for typical symptoms alone will fail to identify approximately half of those with COVID-19 who are elderly, particularly those with frailty and other co-morbidities (Kimball et al., 2020).
The majority of recommendations favour a more sensitive threshold for fever detection in older adults, i.e. 37.5°C or an increase of >1.5°C from usual temperature (Holroyd-Leduc et al., 2020).
Screening of older adults or those with comorbidities should include supplemental questions to determine if atypical symptoms are present such as fatigue, myalgias, headache, conjunctivitis, tachycardia, hypotension, and hypoxia. Presence of atypical symptoms should trigger COVID testing.
Tools developed by the Ontario Ministry of Health (2020) and Alberta Health Services (2020) may be useful guides for healthcare provider screening of individuals at higher risk of COVID-19 infections (i.e. frail older adults with comorbidities).
Prioritization of mass testing should be for those with atypical presentations. Specifically, testing should be commenced first for older adults with changes in delirium, unexplained or increased numbers of falls, weight loss, change in appetite, acute functional decline, or worsening chronic conditions (ON Ministry of Health COVID Screening Guide, 2020).
Tupper, S; Ward, H; Dalidowicz, M; Ellsworth, C. What is the case definition for COVID-19 in elderly people? 2020 Jun 12; Document no.: LTC060201 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 39 p. (CEST rapid review report)
Screening tools commonly include fever, respiratory symptoms (cough, shortness of breath), and epidemiological risk factors.
· The sensitivity and specificity of screening questionnaires depends considerably on the items used in the questionnaire. The limited published literature demonstrates great variability in the performance of different screening tools: sensitivity ranges from 0 – 48.6 – 84.3 – 100%; specificity ranges from 64.8 – 71.3 – 89.6 – 96%).
· The standard WHO symptom checklist performs poorly, with a sensitivity of 48.6%, and specificity of 89.6%. As such, half of individuals who have SARS-CoV-2 present at the time of testing will be missed by the symptom questionnaire (being either asymptomatic or presymptomatic). Depending on the population being screened the prevalence of the virus may vary widely. Given the sensitivity and specificity of the WHO symptom checklist in a population with prevalence ranging from 0.1% to 1% to 10% the positive predictive value (PPV) will be poor, range from 0.4% to 4.8% to 35%, respectively. Furthermore, the performance characteristics of the screening questionnaire may be poorer than reported if used in a setting or time of year when other respiratory viruses with similar symptoms are circulating.
Fick, F; Neudorf, C; Reeder, B; Dalidowicz, M; Mueller, M. What is the sensitivity and specificity of screening checklists and temperature checks for detecting the presence of COVID-19 in individuals? 2020 Apr 28; Document no.: PH042401 RR. In:
COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 20 p. (CEST rapid review report)
McCarron, M; Groot, G; Dalidowicz, M; Miller, L. What distinguishes COVID-19 from influenza-like illnesses? 2020 Apr 17; Document no.: PPE041701 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 5 p. (CEST rapid review report)