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).
· There is little literature on the performance of triage frameworks. However, critiques of frameworks can help to inform the development of future protocols.
· It is ethically problematic to include age as a triage factor rather than the more nuanced factors of frailty and chronic comorbidities.
· The public should be included when creating triage protocols to create transparency and trust in the health system.
· Healthcare providers should be familiar with the ethical decisions that have been made in establishing the protocols. However, using a triage team to make decisions about resource allocation would alleviate moral burden from clinicians.
· Regular review of current guidelines, such as the use of SOFA scores, is recommended as knowledge about COVID-19 changes.
Rapid Review Report: CC120401 RR (Version 1: December 17, 2020 11:45) 2
· Patients should be regularly reassessed to allow for timely redistribution of critical resources.
Fick, F; Valiani, S; Miller, L; Howell-Spooner, B. Does data exist on the performance of triage or resource allocation frameworks for COVID-19 and other pandemics? 2020 Dec 17; Document no.: CC120401 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 91 p. (CEST rapid review report)
No studies directly evaluated the association between level of surge capacity and quality of care indicators for COVID-19 patients. However, in more broad studies, the findings suggest that mortality and other adverse events increase when the strain on the intensive care capacity increases.
A tiered staffing strategy is recommended to meet surge capacity needs in the ICU: High critical care nurse to patient ratios (1:1 or 1:2) are recommended to provide high quality patient care.
There is a lack of high-quality evidence to support ICU triage protocols tailored for patients with COVID-19. Nevertheless, the protocols must be flexible, adaptable according to the availability of local resources, and effective for inter-hospital patient transfer.
While the Crisis Standards of Care (CSC) guidelines (e.g., Saskatchewan’s Critical Care Resource Allocation Framework, published on September 2020) can be used to triage newly admitted COVID-19 patients requiring critical care, there is contradicting evidence about using the Sequential Organ Failure Assessment (SOFA) score for ICU triage of patients with COVID-19.
The literature suggests the use of mathematical modeling to support capacity planning (e.g., very low, low, medium, and high intensity patient surge response)
To relieve pressure from ICUs, other types of units (e.g., Step Down Unit [SDU] or Surge Clinic) can be implemented.
Azizian, A; Valiani, S; Groot, G; Badea, A; Miller, L; Howell-Spooner, B. At what level of surge capacity do quality of care indicators suffer? 2020 Dec 10; Document no.: CC120301 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 17 p. (CEST rapid review report)
· A burgeoning body of research exists about factors associated with in-hospital mortality among COVID-19 patients; however, focus on intensive care settings remains limited.
· The most frequent predictors of critical care mortality integrate age, physiologic markers and laboratory parameters in the most parsimonious models or prognostic scoring systems.
· Commonly used prognostic scoring systems such as MEWS, APACHE and SOFA provide crude mortality risk prediction that may be improved with machine learning algorithms that potentially offer more clinically relevant windows and opportunities for mortality risk prediction prior to deterioration.
Rapid Review Report: CC120402 RR (Version 1: December 9, 2020 14:51) 2
· Between centre variation is potentially an important determinant of critical care mortality that needs to be explored.
Williams-Roberts, H; Valiani, S; McLean, M; Miller, L; Howell-Spooner, B. What are the predictors of mortality in hospitalized COVID-19 patients? 2020 Dec 9; Document no.: CC120402 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 33 p. (CEST rapid review report)