Timing and Predictors of Loss of Infectivity Among Healthcare Workers With Mild Primary and Recurrent COVID-19: A Prospective Observational Cohort Study.

BACKGROUND: There is a need to understand the duration of infectivity of primary and recurrent coronavirus disease 2019 (COVID-19) and identify predictors of loss of infectivity. METHODS: Prospective observational cohort study with serial viral culture, rapid antigen detection test (RADT) and reverse transcription polymerase chain reaction (RT-PCR) on nasopharyngeal specimens of healthcare workers with COVID-19. The primary outcome was viral culture positivity as indicative of infectivity. Predictors of loss of infectivity were determined using multivariate regression model. The performance of the US Centers for Disease Control and Prevention (CDC) criteria (fever resolution, symptom improvement, and negative RADT) to predict loss of infectivity was also investigated. RESULTS: In total, 121 participants (91 female [79.3%]; average age, 40 years) were enrolled. Most (n = 107, 88.4%) had received ≥3 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine doses, and 20 (16.5%) had COVID-19 previously. Viral culture positivity decreased from 71.9% (87/121) on day 5 of infection to 18.2% (22/121) on day 10. Participants with recurrent COVID-19 had a lower likelihood of infectivity than those with primary COVID-19 at each follow-up (day 5 odds ratio [OR], 0.14; P < .001]; day 7 OR, 0.04; P = .003]) and were all non-infective by day 10 (P = .02). Independent predictors of infectivity included prior COVID-19 (adjusted OR [aOR] on day 5, 0.005; P = .003), an RT-PCR cycle threshold [Ct] value <23 (aOR on day 5, 22.75; P < .001) but not symptom improvement or RADT result.The CDC criteria would identify 36% (24/67) of all non-infectious individuals on day 7. However, 17% (5/29) of those meeting all the criteria had a positive viral culture. CONCLUSIONS: Infectivity of recurrent COVID-19 is shorter than primary infections. Loss of infectivity algorithms could be optimized.

SARS-CoV-2 infection among healthcare workers: the role of occupational and household exposures during the first three pandemic waves in Quebec, Canada.

Objective: We described the evolution of SARS-CoV-2 source of infection in a cohort of healthcare workers (HCWs) of Quebec, Canada, during the first three pandemic waves. We also estimated their household secondary attack rate (SAR) and its risk factors. Design: Cross-sectional surveys. Participants: HCWs with a SARS-CoV-2 infection confirmed by polymerasa chain reaction and diagnosed between March 2020 and May 2021. Methods: We collected demographic, clinical, vaccination, and employment information, self-reported perceived source of infection, and transmission to household members during the first three pandemic waves. SAR was calculated for households with ≥2 members where the HCW was the index case. A Poisson regression model estimated the association between risk factors and SAR. Results: Among the 11,670 HCWs completing the survey, 91%, perceived their workplace as the source of infection during the first wave (March-July 2020), 71% during the second wave (July 2020-March 2021), and 40% during the third wave (March-May 2021). Conversely, HCWs reported an increasing proportion of household-acquired infections with each wave from 4% to 14% and 33%, respectively. The overall household SAR of 7,990 HCWs living with ≥1 person was 30% (95%CI: 29-30). SAR increased with the presence of symptoms, older age, and during Alpha-variant predominant period. Conclusions: HCWs and their household members were largely affected during the first pandemic waves of COVID-19, but the relative importance of occupational exposure changed overtime. Pandemic preparedness in healthcare settings is essential to protect HCWs from emerging biological hazard exposures.

Risk and protective factors for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection among healthcare workers: A test-negative case-control study in Québec, Canada.

OBJECTIVES: In Québec, Canada, we evaluated the risk of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection associated with (1) the demographic and employment characteristics among healthcare workers (HCWs) and (2) the workplace and household exposures and the infection prevention and control (IPC) measures among patient-facing HCWs. DESIGN: Test-negative case-control study. SETTING: Provincial health system. PARTICIPANTS: HCWs with PCR-confirmed coronavirus disease 2019 (COVID-19) diagnosed between November 15, 2020, and May 29, 2021 (ie, cases), were compared to HCWs with compatible symptoms who tested negative during the same period (ie, controls). METHODS: Adjusted odds ratios (aORs) of infection were estimated using regression logistic models evaluating demographic and employment characteristics (all 4,919 cases and 4,803 controls) or household and workplace exposures and IPC measures (2,046 patient-facing cases and 1,362 controls). RESULTS: COVID-19 risk was associated with working as housekeeping staff (aOR, 3.6), as a patient-support assistant (aOR, 1.9), and as nursing staff (aOR, 1.4), compared to administrative staff. Other risk factors included being unexperienced (aOR, 1.5) and working in private seniors' homes (aOR, 2.1) or long-term care facilities (aOR, 1.5), compared to acute-care hospitals. Among patient-facing HCWs, exposure to a household contact was reported by 9% of cases and was associated with the highest risk of infection (aOR, 7.8). Most infections were likely attributable to more frequent exposure to infected patients (aOR, 2.7) and coworkers (aOR, 2.2). Wearing an N95 respirator during contacts with COVID-19 patients (aOR, 0.7) and vaccination (aOR, 0.2) were the measures associated with risk reduction. CONCLUSION: In the context of the everchanging SARS-CoV-2 virus with increasing transmissibility, measures to ensure HCW protection, including vaccination and respiratory protection, and patient safety will require ongoing evaluation.

Infectivity of healthcare workers diagnosed with coronavirus disease 2019 (COVID-19) approximately 2 weeks after onset of symptoms: A cross-sectional study.

We performed viral culture of respiratory specimens in 118 severe acute respiratory coronavirus virus 2 (SARS-CoV-2)-infected healthcare workers (HCWs), ∼2 weeks after symptom onset. Only 1 HCW (0.8%) had a positive culture. No factors for prolonged viral shedding were identified. Infectivity is resolved in nearly all HCWs ∼2 weeks after symptom onset.

Characterization and evolution of infection control practices among severe acute respiratory coronavirus virus 2 (SARS-CoV-2)-infected healthcare workers in acute-care hospitals and long-term care facilities in Québec, Canada, Spring 2020.

OBJECTIVES: In this study, we aimed to (1) estimate the severe acute respiratory coronavirus 2 (SARS-CoV-2) infection rate and the secondary attack rate among healthcare workers (HCWs) in Québec, the most affected province of Canada during the first wave; (2) describe the evolution of work-related exposures and infection prevention and control (IPC) practices in infected HCWs; and (3) compare the exposures and practices between acute-care hospitals (ACHs) and long-term care facilities (LTCFs). DESIGN: Survey of cases. PARTICIPANTS: The study included Québec HCWs from private and public institutions with laboratory-confirmed coronavirus disease 2019 (COVID-19) diagnosed between March 1 and June 14, 2020. HCWs aged ≥18 years who worked during the exposure period and survived their illness were eligible for the survey. METHODS: After obtaining consent, 4,542 HCWs completed a standardized questionnaire. COVID-19 rates and proportions of exposures and practices were estimated and compared between ACHs and LTCFs. RESULTS: HCWs represented 13,726 (25%) of 54,005 reported COVID-19 cases in Québec and had an 11-times greater rate of COVID-19 than non-HCWs. Their secondary household attack rate was 30%. Most affected occupations were healthcare support workers, nurses and nurse assistants working in LTCFs (45%) and ACHs (30%). Compared to ACHs, HCWs in LTCFs had less training, higher staff mobility between working sites, similar PPE use, and better self-reported compliance with at-work physical distancing. Suboptimal IPC practices declined over time but were still present at the end of the first wave. CONCLUSION: Québec HCWs and their families were severely affected during the first wave of COVID-19. Insufficient pandemic preparedness and suboptimal IPC practices likely contributed to high transmission in both LTCFs and ACHs.

Role of high-risk antibiotic use in incidence of health-care-associated Clostridioides difficile infection in Quebec, Canada: a population-level ecological study.

BACKGROUND: The incidence of health-care-associated Clostridioides difficile infections has been declining in the Canadian province of Quebec since 2015. We examined whether changes in high-risk antibiotic use could account for this decrease, as reported in other jurisdictions. METHODS: We did a retrospective interrupted time-series analysis of 12 hospitals in the Canadian province of Quebec, representing a quarter of all health-care-associated C difficile infections in this region between April 1, 2012, and March 31, 2017. Data for high-risk antibiotic use (eg, amoxicillin-clavulanate, cephalosporins, fluoroquinolones, and clindamycin) in defined daily doses (DDDs) were extracted from local surveillance databases, and incidences of health-care-associated C difficile infections were extracted from provincial surveillance databases. We used hierarchical segmented Poisson regression to assess whether variations in rates of health-care-associated C difficile infections followed variations in antibiotic use. FINDINGS: Overall, 4455 health-care-associated C difficile infections and 6 281 960 patient-days were reported in the 12 participating hospitals, representing around a quarter of the provincial data. A 50% decrease in the annual incidence of health-care-associated C difficile infections was recorded between 2012-13 and 2016-17 (9·4 infections per 10 000 patient-days vs 4·7 infections per 10 000 patient-days), and a 67% decrease in the proportion of these infections due to the NAP1/027 strain of C difficile was seen (64% in 2013 vs 21% in 2017). In total, 1 266 960 DDDs of high-risk antibiotics were distributed during the study period. An increasing time trend was noted in high-risk antibiotic use, reaching a total of 223 DDDs per 1000 patient-days in 2016-17. An increase of one DDD per 1000 patient-days was associated with a 0·2% increase in the rate of health-care-associated C difficile infections in the following 4-week period. A significant change in incidence of health-care-associated C difficile infections persisted despite adjustment for high-risk antibiotic use, as shown by a significant residual step change (0·825, 95% CI 0·731-0·932) and change in trend (0·987, 0·980-0·994). INTERPRETATION: Changes in use of high-risk antibiotics do not entirely account for the sudden decrease in health-care-associated C difficile infections in the Canadian province of Quebec since 2015. Further studies are needed to understand factors implicated in the change in epidemiology of health-care-associated C difficile infections. FUNDING: Institut National de Santé Publique du Québec.

Increased Community-Associated Clostridioides difficile Infections in Quebec, Canada, 2008-20151.

The annual incidence rate of community-associated Clostridioides difficile infections in Quebec, Canada, has increased by 33.3%, from 0.51 (2008) to 0.68 (2015) cases/100,000 population, while incidence of healthcare-associated cases remained relatively stable. Possible causes include increased disease severity, increased antimicrobial drug use, emergence of virulent strains, and heightened physician awareness.

Changes in vascular accesses and in incidence rates of dialysis-related bloodstream infections in Québec, Canada, 2011-2017.

OBJECTIVE: Surveillance of dialysis-related bloodstream infections (DRBSIs) has been mandatory in Québec since April 2011. The aim of this study was to describe the epidemiology of DRBSIs in Québec. METHODS: Cohort study of prevalent patients undergoing chronic dialysis in the 36 facilities that participated without interruption in the provincial surveillance, between April 2011 and March 2017. Two indicators were analyzed: proportion of patient months dialyzed using a fistula (a patient month is a 28-day cycle during which an individual patient received dialysis) and incidence rate of DRBSI. Binomial and Poisson regression with generalized estimating equations were used to describe the evolution of indicators over time and to quantify the association between facilities' proportion of fistulas and their incidence rate. RESULTS: Globally, 42.6% of all patient months were dialyzed using a fistula, but there was a statistically significant decrease over time (46.2% in 2011-2012 to 39.3% in 2016-2017). Despite this decline in the use of fistulas, rates of DRBSIs have also decreased, going from 0.38 DRBSIs per 100 patient months in 2011-2012 to 0.23 DRBSIs per 100 patient months in 2016-2017. No association was found between facility use of fistulas and the rate of DRBSI. At the individual level, however, the DRBSI rate was 4.12 times higher for patients using a catheter. CONCLUSIONS: In Québec, the rate of DRBSIs has decreased over a 6-year period despite an increasing proportion of patients dialyzed by catheter.

Healthcare-associated bloodstream infection trends under a provincial surveillance program.

OBJECTIVE: BACTOT, Quebec's healthcare-associated bloodstream infection (HABSI) surveillance program has been operating since 2007. In this study, we evaluated the changes in HABSI rates across 10 years of BACTOT surveillance under a Bayesian framework. DESIGN: A retrospective, cohort study of eligible hospitals having participated in BACTOT for at least 3 years, regardless of their entry date. Multilevel Poisson regressions were fitted independently for cases of HABSI, catheter-associated bloodstream infections (CA-BSIs), non-catheter-associated primary BSIs (NCA-BSIs), and BSIs secondary to urinary tract infections (BSI-UTIs) as the outcome and log of patient days as the offset. The log of the mean Poisson rate was decomposed as the sum of a surveillance year effect, period effect, and hospital effect. The main estimate of interest was the cohort-level rate in years 2-10 of surveillance relative to year 1. RESULTS: Overall, 17,479 cases and 33,029,870 patient days were recorded for the cohort of 77 hospitals. The pooled 10-year HABSI rate was 5.20 per 10,000 patient days (95% CI, 5.12-5.28). For HABSI, CA-BSI, and BSI-UTI, there was no difference between the estimated posterior rates of years 2-10 compared to year 1. The posterior means of the NCA-BSI rate ratios increased from the seventh year until the tenth year, when the rate was 29% (95% confidence interval, 1%-89%) higher than the first year rate. CONCLUSIONS: HABSI rates and those of the most frequent subtypes remained stable over the surveillance period. To achieve reductions in incidence, we recommend that more effort be expended in active interventions against HABSI alongside surveillance.

A ten-year review of healthcare-associated bloodstream infections from forty hospitals in Québec, Canada.

OBJECTIVE: Healthcare-associated bloodstream infections (HABSI) are a significant cause of morbidity and mortality worldwide. In Québec, Canada, HABSI arising from acute-care hospitals have been monitored since April 2007 through the Surveillance des bactériémies nosocomiales panhospitalières (BACTOT) program, but this is the first detailed description of HABSI epidemiology. METHODS: This retrospective, descriptive study was conducted using BACTOT surveillance data from hospitals that participated continuously between April 1, 2007, and March 31, 2017. HABSI cases and rates were stratified by hospital type and/or infection source. Temporal trends of rates were analyzed by fitting generalized estimating equation Poisson models, and they were stratified by infection source. RESULTS: For 40 hospitals, 13,024 HABSI cases and 23,313,959 patient days were recorded, for an overall rate of 5.59 per 10,000 patient days (95% CI, 5.54-5.63). The most common infection sources were catheter-associated BSIs (23.0%), BSIs secondary to a urinary focus (21.5%), and non-catheter-associated primary BSIs (18.1%). Teaching hospitals and nonteaching hospitals with ICUs often had rates higher than nonteaching hospitals without ICUs. Annual HABSI rates did not exhibit statistically significant changes from year to year. Non-catheter-associated primary BSIs were the only HABSI type that exhibited a sustained change across the 10 years, increasing from 0.69 per 10,000 patient days (95% CI, 0.59-0.80) in 2007-2008 to 1.42 per 10,000 patient days (95% CI, 1.27-1.58) in 2016-2017. CONCLUSIONS: Despite ongoing surveillance, overall HABSI rates have not decreased. The effect of BACTOT participation should be more closely investigated, and targeted interventions along alternative surveillance modalities should be considered, prioritizing high-burden and potentially preventable BSI types.

Hospital-Acquired Methicillin-Resistant Staphylococcus aureus Bloodstream Infections in Québec: Impact of Guidelines.

OBJECTIVE We examined the impact of methicillin-resistant Staphylococcus aureus (MRSA) guidelines in Québec adult hospitals from January 1, 2006, to March 31, 2015, by examining the incidence rate reduction (IRR) in healthcare-associated MRSA bloodstream infections (HA-MRSA), using central-line associated bloodstream infections (CLABSIs) as a comparator. METHODS In this study, we utilized a quasi-experimental design with Poisson segmented regression to model HA-MRSA and CLABSI incidence for successive 4-week surveillance segments, stratified by teaching status. We used 3 distinct periods with 2 break points (April 1, 2007, and January 3, 2010) corresponding to major MRSA guideline publications and updates. RESULTS Over the study period, HA-MRSA incidence decreased significantly in adult teaching facilities but not in nonteaching facilities. Prior to MRSA guideline publication (2006-2007), HA-MRSA incidence decrease was not significant (P=.89), while CLABSI incidence decreased by 4% per 4-week period (P=.05). After the publication of guidelines (2007-2009), HA-MRSA incidence decreased significantly by 1% (P=.04), while no significant decrease in CLABSI incidence was observed (P=.75). HA-MRSA and CLABSI decreases were both significant at 1% for 2010-2015 (P<.001 and P=.01, respectively). These decreases were gradual rather than sudden; break points were not significant. Teaching facilities drove these decreases. CONCLUSION During the study period, HA-MRSA and CLABSI rates decreased significantly. In 2007-2009, the significant decrease in HA-MRSA rates with stable CLABSI rates suggests an impact from MRSA-specific guidelines. In 2010-2015, significant and equal IRRs for HA-MRSA and CLABSI may be due to the continuing impact of MRSA guidelines, to the impact of new interventions targeting device-associated infections in general by the 2010-2015 Action Plan, or to a combination of factors. Infect Control Hosp Epidemiol 2017;38:840-847.

Early Radiographic and Tomographic Manifestations of Legionnaires' Disease.

PURPOSE: Legionnaires' disease (LD) may occur sporadically or in the course of outbreaks, where the typical radiological manifestations of the disease may better be delineated. We took advantage of a rare community-based epidemic of LD (181 patients) that occurred in 2012 in Quebec City, Canada, to describe the radiographic features of LD and compare the its tomographic presentation with that of community-acquired pneumonia caused by common bacteria other than Legionella pneumophila. METHODS: From the 181 individuals affected in the outbreak, we obtained the chest radiographs of 159 individuals (mean 63 ± 15 years of age) for detailed analysis; 33 patients had a computed tomography (CT) scan performed during the course of their illness. In a case-control study, we compared the CT scans of patients with LD with those of patients who had received a diagnosis of community-acquired pneumonia caused by a pathogen other than Legionella and confirmed by chest CT scan. RESULTS: Overall, LD most often presented as an airspace consolidation involving 1 of the lower lobes. Pleural effusion and mediastinal adenopathies were apparent only in a minority, whereas no pneumothorax or cavitation was noted. We did not find any significant difference in chest CT scan findings in patients with LD vs those with community-acquired pneumonia from other bacterial origin. No radiological finding was clearly associated with an increased risk of intensive care unit admission or mortality. CONCLUSIONS: The early radiographic and tomographic manifestations of LD are nonspecific and similar to those found in community-acquired pneumonia from other bacterial origin.