In October, WHO released a consensus definition of post COVID-19 condition that includes 12 domains. This development should lead to better standardization of reporting and contribute to more precise prevalence estimates and better understanding of associated risk factors.
The effects of Variants of Concern (VoC) and COVID vaccination on progression of Long COVID symptoms remains unclear.
Risk factors for developing Long COVID symptoms were similar but limited evidence suggests that pre-pandemic psychological distress and poor general health were associated with developing persistent symptoms. Evidence is too limited to determine whether vaccination reduces the risk of developing Long COVID among persons with breakthrough infections.
Given the protean manifestations of Long COVID symptoms, the underlying causes are likely multifactorial; however, strong evidence to substantiate the theories of causation remains limited.
Research related to longer-term consequences of SARS CoV-2 infections in pediatric populations is growing but remains limited.
March 15, 2021
There is a lack of consensus around the clinical definition of Long COVID which in turn causes challenges with understanding the incidence and prevalence as well as the potential impact for the health care system
Information about the natural history of Long COVID is incomplete but limited evidence suggests that the immune response trajectories differ for those with few or no symptoms compared to those with severe disease. Individuals with severe disease are more likely to exhibit immunological marker abnormalities but anyone can experience functional limitations.
The mechanisms underlying the development of persistent symptoms in Long COVID remain an enigma. Despite multiple theories, there is little empirical evidence for specific immunological and or biochemical abnormalities in samples of individuals with symptoms consistent with Long COVID.
Risk factors for Long COVID include female gender, older age, higher body mass index, pre-existing asthma and the number of symptoms.
Few studies explored the short-term impact of Long COVID on health care utilization patterns and found a higher impact for those with severe disease compared with mild disease.
Williams-Roberts, H; Groot, G; Mueller, M; Dalidowicz, M. Long COVID: What does it mean for the healthcare system and programs? 2021 Oct 29. Document no.: EOC021901v2 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2021. 14 p. (CEST rapid review report).
Long COVID-19 is likely to increase healthcare demands across the health system, including emergency departments, hospital admissions, primary care visits, specialists appointments, and home care and rehabilitation services.
The clinical care burden of long COVID-19 is the greatest in the first 3 months after testing and is likely to place the greatest demand on primary care services.
Patients with severe COVID-19 illness are more likely to place longer-term demands (4-6 months) on specialist care due to respiratory, circulatory, endocrine, metabolic, psychiatric and unspecified conditions.
McLean, M; Williams-Roberts, H; Reeder, B; Howell-Spooner, B; Ellsworth, C. What are long COVID's demands on the healthcare system, and its severity of the illness? 2021 Jul 12, Document no.: EPM210602 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2021. 23 p. (CEST rapid review report).
The frequency of Long COVID symptoms varies widely across studies based on populations studied, duration of follow up and methods of assessment of symptoms.
It is estimated that 1 in 50 persons experience Long COVID symptoms after 12 weeks; however, higher estimates up to 80% have been reported in studies with a greater proportion of persons who were previously hospitalized. A recent study of a mixed cohort of 96 persons found that only 22.9% had no symptoms at 12 months post diagnosis.
A wide range of symptoms affecting multiple organ systems has been reported. For many persons symptoms improve over time while others experience persistent and/or new symptoms. Among studies with the longest duration of follow up, the most frequently reported symptoms included fatigue (up to 65%), dyspnea (up to 50%), headache (up to 45%), anosmia/ageusia (up to 25%), cognitive memory/concentration (up to 39.6%) and sleep disorders (up to 26%).
Few studies estimated the duration of symptoms with estimates ranging from 2.2% for 6 months and 27% for 7-9 months.
The mechanism(s) leading to Long COVID remain unclear but those experiencing post acute sequelae tend to be older, have a greater number of symptoms during the acute phase of illness or manifest specific symptoms and live with multiple comorbid conditions such as obesity.
The lack of consensus on a definition of Long COVID contributes to marked variations in robust prevalence estimates.
Williams-Roberts, H; Groot, G; Reeder, B; Howell-Spooner, B; Ellsworth, C. What is the incidence and duration of Long COVID cases? 2021 Jul 09, Document no.: EPM210601 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2021. 19 p. (CEST rapid review report).
The group designated in Saskatchewan as Clinically Extremely Vulnerable (CEV) is a heterogenous clinical population with factors that impair their immune response to differing degrees.
Very Limited evidence is currently available to assess the immune response following vaccination is selected clinical populations; no evidence is available to assess vaccine efficacy or effectiveness in these populations. The clinical relevance of measured immune response with respect to protection from disease is still uncertain.
In considering the immune response of the CEV population, it is recommended that the absolute difference in immune response between 1 and 2 doses be considered, as it is possible some patient groups will have lowered protection regardless of vaccine strategy.
In terms of clinical subgroups:
oOrgan transplantation recipients on immunosuppressive medication: solid organ transplant recipients receiving anti-metabolite maintenance immunosuppression therapy were less likely to develop an antibody response to an mRNA vaccine, compared to those receiving other types of therapies (37% vs 63%). In a study of 242 kidney transplant recipients on immunosuppressive therapy only 10.8% became seropositive at 28 days after a single dose of mRNA vaccine.
oCancer: A study of 151 elderly patients with solid and hematological malignancies and 54 healthy controls who received one or two doses of BNT162b2 (Pfizer-BioNTech) vaccine shows approximately 39% of solid cancer patients, 13% of hematological cancer patients, and 97% of healthy controls (p<0.0001) developed anti-S IgG 21 days following a single dose vaccine. However, response in solid cancer patients increased to 95% within 2 weeks of the second dose at 21 days.
oOther immunocompromising conditions (e.g., auto-immune disorders and therapy): some level of immunity is generated with vaccination; however, what this means clinically is unknown. It seems that ensuring the dosing is properly timed around biologic therapy is important.
Azizian, A; Lee, S; Shumilak, G; Groot, G; Reeder, B; Miller, L; Howell-Spooner, B. What are the risks or benefits of extended intervals between doses of COVID-19 vaccines compared to recommended dosing in extremely vulnerable populations? 2021 Apr 20, Document no.: EOC210302 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2021. 15 p. (CEST rapid review report).
Badea, A; Groot, G; Fox, L; Mueller, M. What is the risk of COVID-19 transmission during AGMP procedures? 2020 Dec 18; Document no.: PPE120901 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 30 p. (CEST rapid review report)
Tupper, S; Ward, H; Howell-Spooner, B; Dalidowicz, M; What are the impacts on the family unit from visitation restrictions during an infectious disease outbreak and how can we support the families? 2020 May 14; Document no.: LTC042403 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 38 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)
· There are some recommendations and precautions from WHO, CDC, Canada and the UK that there is transmission of the COVID virus from the administration of nebulizer medication.
· Some case studies of SARS found few instances that patients may likely be infected after aerosol generating procedures including nebulized medications, and although there are few evidences that demonstrates low risk of viral transmission from nebulizers, possibility of transmission remains
Badea, A; Groot, G; Fenton, M; Dalidowicz, M; Young, C. What is the degree of COVID-19 transmission through the administration of nebulizer medication either in clinical practice or in animal experiments? 2020 Apr 1; Document no.: EOC040101 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 10 p. (CEST rapid review report)
· Some countries like Taiwan and Malaysia have created their own intubation hood design as others offered to produce or modify the original design to fit their country’s equipment.
· Several countries have also created innovation in airway management such as 3D printed respirator valves for hospitals and 3D printed ventilators.
· An Emergency physician in Northern Italy shared that due to influx of patients in the hospitals, “intubation and invasive mechanical ventilators in the ED are reserved for patients not responsive to NIV” although in principle can give a more favorable chance for patients if given before their condition deteriorates.
Badea, A; Groot, G; Dalidowicz, M. Where and how are they producing and using intubation hoods? 2020 Mar 30; Document no.: EOC033001 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 7 p. (CEST rapid review report)