Most of the reference exposure studies observed the morbidity/mortality of individuals working in sterilization plants with direct, chronic exposure to high concentrations of ethylene oxide gas prior to changes in allowable environmental levels in 1985, and also formed the basis for the United States Environmental Protection Agency (EPA) and National Institute for Occupational Safety and Health (NIOSH) findings of cancer causation
Meta-analyses of more recent observational cohort studies performed in the 2000s and 2010s of sterilization workers directly exposed to ethylene oxide gas in the workplace do not support the association between ethylene oxide exposure and increased risk of lymphohematopoietic or breast cancers
The elimination half-life of ethylene oxide in humans is approximately 42 minutes – thus almost 90% of any ethylene oxide in a single exposure would be eliminated from the body in two hours
In order to gain FDA approval, testing swabs need to have demonstrated to meet tolerable contact limits of ethylene oxide residuals – experts claim that once packaged for a period of time and aerated prior to use, it is unlikely to contain any ethylene oxide residuals; corroborated by a study assessing the residuals on DNA swabs, finding no detectable levels of ethylene oxide on swabs 3 weeks after sterilization treatment
Badea, A; Groot, G; Hernandez-Ronquillo, L; Fox, L; Mueller, M. What are the risks associated with repeated exposure to Ethylene Oxide from ongoing use of the Abbott Panbio AG COVID-19 Nasal swabs? 2021 Nov 30. Document no.: EOC211126 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2021. 14 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).
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)