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Open Forum Infectious Diseases ; 8(SUPPL 1):S307, 2021.
Article in English | EMBASE | ID: covidwho-1746583


Background. Several factors have been associated with severity of COVID-19 disease, but there remains a paucity of data surrounding whether the nature of exposure is impactful. Evidence demonstrating the correlation between initial viral exposure dose and disease severity exists for many viral infections. Observational studies have suggested that the exposure context, which can be considered a proxy for magnitude of viral inoculum, may influence severity of COVID-19 infection. We aimed to assess whether having a known exposure, as a proxy for higher inoculum dose to COVID-19, was associated with more severe outcomes for individuals hospitalized with COVID-19. Methods. We created a retrospective cohort of community-dwelling adults hospitalized for COVID-19 in south-central Ontario from April 1, 2020 - January 14, 2021. Individuals or next of kin were contacted to ascertain exposure history. The primary outcome was death, intensive care unit (ICU) admission, or mechanical ventilation (MV) within 30 days of admission. A multivariable logistic regression model was used to determine whether a known exposure was associated with worse outcomes. Results. 1097 individuals with community acquired COVID-19 required hospitalization;of these, 942 (86%) had available exposure data. In this group, the median age was 65, 44% were women, 84% lived in a private residence, 59% had a frailty score (FS) of 1 - 3 while 40% had a FS of 4 - 9, and 28% had a known exposure. Overall, the primary outcome occurred in 368/942 (39%) patients. Having a known exposure was not associated with worse outcome (OR 1.14, 95% CI 0.84-1.54, p = 0.41). Male gender (OR 1.41, 95% CI 1.06-1.89;p = 0.018), age (OR 1.01/year, 95% CI 1.00-1.03, p = 0.03), frailty (OR 1.22/point, 95% CI 1.09-1.36, p = 0.001) and living with at least one other person (OR 1.57, 95% CI 1.09-2.28, p = 0.017) were all associated with death, ICU admission, or MV within 30 days of admission. Conclusion. While having a known exposure to a person with COVID-19 was not associated with worse outcome, the identified increased severity of illness associated with cohabitation suggests context of exposure may have a role in disease severity. This data and future studies can be used to guide public health recommendations to not only minimize transmission, but severity of COVID-19 infection.

Embase; 2021.
Preprint in English | EMBASE | ID: ppcovidwho-330471


Although SARS-CoV-2 infects the upper respiratory tract, we know little about the amount, type, and kinetics of antibodies (Ab) generated at this site in response to intramuscular COVID-19 vaccination, and whether these Ab protect against subsequent “breakthrough” infections. We collected longitudinal serum and saliva samples from participants receiving two doses of mRNA COVID-19 vaccines over a 6-month period and measured the relative level of anti-Spike and anti-Receptor Binding Domain (RBD) Ab. We detected anti-Spike/RBD IgG and IgA and associated secretory component in the saliva of most participants receiving 1 dose of mRNA vaccine. Administration of a second dose of mRNA boosted the IgG but not the IgA response, with only 30% of participants remaining positive for IgA at this timepoint. At 6 months post-dose 2, these participants exhibited greatly diminished anti-Spike/RBD IgG and IgA levels concomitant with a reduction in neutralizing activity in the saliva, although the level of secretory component associated anti-Spike was less susceptible to decay. Examining two prospective cohorts of subjects that were monitored for infections post-vaccination, we found that participants who were subsequently infected with SARS-CoV-2 had lower levels of vaccine-induced serum anti-Spike/RBD IgA at 2-4 weeks post-dose 2 compared to participants who did not experience an infection, whereas IgG levels were comparable between groups. These data emphasize the importance of developing COVID-19 vaccines that elicit a durable IgA response.

Antimicrobial Resistance and Infection Control ; 10(SUPPL 1), 2021.
Article in English | EMBASE | ID: covidwho-1448341


Introduction: There is insufficient evidence regarding the role of respirators in the prevention of SARS-CoV-2 infection. Objectives: We analysed the impact of filtering facepiece class 2 (FFP2) vs. surgical masks on the risk of SARS-CoV-2 acquisition in Swiss healthcare workers (HCW). Methods: Our prospective multicentre cohort enrolled HCW from June to August 2020, who were asked about COVID-19 risk exposures/behaviours, including preferred mask type when caring for COVID-19 patients outside of aerosol-generating procedures (AGP). HCW performing AGP were also asked about universal FFP2 use (i.e. irrespective of patients' COVID-19 status). We assessed the impact of FFP2 on i) self-reported SARS-CoV- 2-positive nasopharyngeal PCR/rapid antigen tests (weekly surveys), and ii) SARS-CoV-2 seroconversion (baseline to January/February 2021). Results: We enrolled 3'259 participants from nine healthcare institutions, whereof 716 (22%) preferentially used FFP2 respirators. Among these, 81/716 (11%) reported a SARS-CoV-2-positive swab, compared to 352/2543 (14%) surgical mask users (median follow-up 242 days);seroconversion was documented in 85/656 (13%) FFP2 and 426/2255 (19%) surgical mask users. Adjusted for baseline characteristics, COVID-19 exposure, and risk behaviour, FFP2 use was marginally associated with a decreased risk for SARS-CoV-2-positive swab (aHR 0.8, p = 0.052) and seroconversion (aOR 0.7, p = 0.053);household exposure was the strongest risk factor (aHR for positive swab 10.1, p < 0.001;aOR for seroconversion 5.0, p < 0.001). In subgroup analysis, FFP2 use was clearly protective among HCW with frequent (> 20 patients) COVID-19 exposure (aHR 0.7, p < 0.001;aOR 0.6, p = 0.036). Universal FFP2 use during AGP showed no additional protective effect (aHR 1.1, p = 0.7;aOR 0.9, p = 0.53). Conclusion: FFP2 compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients. (Figure Presented).