Brigitte Comte

Estimating Potential Infection Transmission Routes in Hospital Wards Using Wearable Proximity Sensors

Background Contacts between patients, patients and health care workers (HCWs) and among HCWs represent one of the important routes of transmission of hospital-acquired infections (HAI). A detailed description and quantification of contacts in hospitals provides key information for HAIs epidemiology and for the design and validation of control measures. Methods and Findings We used wearable sensors to detect close-range interactions (“contacts”) between individuals in the geriatric unit of a university hospital. Contact events were measured with a spatial resolution of about 1.5 meters and a temporal resolution of 20 seconds. The study included 46 HCWs and 29 patients and lasted for 4 days and 4 nights. 14,037 contacts were recorded overall, 94.1% of which during daytime. The number and duration of contacts varied between mornings, afternoons and nights, and contact matrices describing the mixing patterns between HCW and patients were built for each time period. Contact patterns were qualitatively similar from one day to the next. 38% of the contacts occurred between pairs of HCWs and 6 HCWs accounted for 42% of all the contacts including at least one patient, suggesting a population of individuals who could potentially act as super-spreaders. Conclusions Wearable sensors represent a novel tool for the measurement of contact patterns in hospitals. The collected data can provide information on important aspects that impact the spreading patterns of infectious diseases, such as the strong heterogeneity of contact numbers and durations across individuals, the variability in the number of contacts during a day, and the fraction of repeated contacts across days. This variability is however associated with a marked statistical stability of contact and mixing patterns across days. Our results highlight the need for such measurement efforts in order to correctly inform mathematical models of HAIs and use them to inform the design and evaluation of prevention strategies.

Risk of Influenza-Like Illness in an Acute Health Care Setting During Community Influenza Epidemics in 2004-2005, 2005-2006, and 2006-2007: A Prospective Study

BACKGROUND The person-to-person transmission of influenza-like illness (ILI) and influenza has been described mostly in long-term care units. Studies in acute hospital settings are rare and mostly retrospective. METHODS We prospectively estimated the relative risk (RR) of hospital-acquired (HA) ILI during hospitalization according to in-hospital exposures to contagious individuals. Surveillance of ILI and laboratory-confirmed influenza was undertaken at Edouard Herriot Hospital (1100 beds) during 3 influenza seasons. A total of 21 519 patients and 2153 health care workers (HCWs) from 2004 to 2007 were included. The RR of HA-ILI in patients was calculated according to exposure to other contagious patients and HCWs. RESULTS For patients exposed to at least 1 contagious HCW compared with those with no documented exposure in the hospital, the RR of HA-ILI was 5.48 (95% confidence interval [CI], 2.09-14.37); for patients exposed to at least 1 contagious patient, the RR was 17.96 (95% CI, 10.07-32.03); and for patients exposed to at least 1 contagious patient and 1 contagious HCW, the RR was 34.75 (95% CI, 17.70-68.25). CONCLUSIONS Hospitalized patients exposed to potentially infectious patients and HCWs with ILI inside the hospital are at greater risk for HA-ILI. Such results identify priorities regarding preventive measures for seasonal or pandemic influenza.

Influenza vaccination of healthcare workers in acute-care hospitals: a case-control study of its effect on hospital-acquired influenza among patients

BackgroundIn acute-care hospitals, no evidence of a protective effect of healthcare worker (HCW) vaccination on hospital-acquired influenza (HAI) in patients has been documented. Our study objective was to ascertain the effectiveness of influenza vaccination of HCW on HAI among patients.MethodsA nested case-control investigation was implemented in a prospective surveillance study of influenza-like illness (ILI) in a tertiary acute-care university hospital. Cases were patients with virologically-confirmed influenza occurring ≥ 72 h after admission, and controls were patients with ILI presenting during hospitalisation with negative influenza results after nasal swab testing. Four controls per case, matched per influenza season (2004-05, 2005-06 and 2006-07), were randomly selected. Univariate and multivariate conditional logistic regression models were fitted to assess factors associated with HAI among patients.ResultsIn total, among 55 patients analysed, 11 (20%) had laboratory-confirmed HAI. The median HCW vaccination rate in the units was 36%. The median proportion of vaccinated HCW in these units was 11.5% for cases vs. 36.1% for the controls (P = 0.11); 2 (20%) cases and 21 (48%) controls were vaccinated against influenza in the current season (P = 0.16). The proportion of ≥ 35% vaccinated HCW in short-stay units appeared to protect against HAI among patients (odds ratio = 0.07; 95% confidence interval 0.005-0.98), independently of patient age, influenza season and potential influenza source in the units.ConclusionsOur observational study indicates a shielding effect of more than 35% of vaccinated HCW on HAI among patients in acute-care units. Investigations, such as controlled clinical trials, are needed to validate the benefits of HCW vaccination on HAI incidence in patients.

Combining High-Resolution Contact Data with Virological Data to Investigate Influenza Transmission in a Tertiary Care Hospital

OBJECTIVE Contact patterns and microbiological data contribute to a detailed understanding of infectious disease transmission. We explored the automated collection of high-resolution contact data by wearable sensors combined with virological data to investigate influenza transmission among patients and healthcare workers in a geriatric unit. DESIGN Proof-of-concept observational study. Detailed information on contact patterns were collected by wearable sensors over 12 days. Systematic nasopharyngeal swabs were taken, analyzed for influenza A and B viruses by real-time polymerase chain reaction, and cultured for phylogenetic analysis. SETTING An acute-care geriatric unit in a tertiary care hospital. PARTICIPANTS Patients, nurses, and medical doctors. RESULTS A total of 18,765 contacts were recorded among 37 patients, 32 nurses, and 15 medical doctors. Most contacts occurred between nurses or between a nurse and a patient. Fifteen individuals had influenza A (H3N2). Among these, 11 study participants were positive at the beginning of the study or at admission, and 3 patients and 1 nurse acquired laboratory-confirmed influenza during the study. Infectious medical doctors and nurses were identified as potential sources of hospital-acquired influenza (HA-Flu) for patients, and infectious patients were identified as likely sources for nurses. Only 1 potential transmission between nurses was observed. CONCLUSIONS Combining high-resolution contact data and virological data allowed us to identify a potential transmission route in each possible case of HA-Flu. This promising method should be applied for longer periods in larger populations, with more complete use of phylogenetic analyses, for a better understanding of influenza transmission dynamics in a hospital setting.

Influenza vaccine effectiveness among adult patients in a University of Lyon hospital (2004-2009).

The aim of this study was to estimate influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza among hospitalized patients. A case-control investigation was based on the prospective surveillance of influenza-like illness (ILI) during five flu seasons. We compared influenza-positive cases and influenza-negative controls. Unadjusted overall IVE was 62% (95% confidence interval 24% to 81%). We found that IVE was lower during the 2004-05 flu season (11%; 95% CI -232% to 76%) when the vaccine and circulating viruses were mismatched. Expansion of the study to other hospitals could provide IVE estimates earlier in the season, for different age groups and emerging virus strains.

Detection of hospital outbreaks of influenza-like illness based on excess of incidence rates compared to the community

The risk of nosocomial influenza-like illness (noso-ILI) compared with that of community-acquired ILI was calculated during 3 influenza seasons (2004-2007) at a 1100-bed university hospital with a total of 21,519 hospitalized patients. Outbreaks of noso-ILI occurred in each season, although a protective effect against noso-ILI was also identified for other wards.

Health care workers travelling abroad: Investigation of carbapenemase-producing enterobacteriaceae infection possibly acquired overseas

Carbapenemase-producing enterobacteriaceae (CPE) are currently emerging worldwide.1 International travel is playing a growing role in the acquisition and spread of antimicrobial-resistant enterobacteriaceae.2 In France, 299 CPE episodes have been reported to the French Institute for Public Health Surveillance between 2004 and 2012; most of them have been linked to foreign travel, ie, medical repatriation, hospitalization abroad, or tourism.1 CPE are frequently hospital acquired, but the source of infection is often difficult to track. Also, whereas health care worker (HCW) colonization by CPE associated with international travel might constitute a major cause of emergent CPE nosocomial outbreaks, to the best of our knowledge, no information is available on HCW travelling in high-risk countries. We describe HCW travel history in the framework of a nosocomial CPE case investigation. This study was performed in the 1,000-bed Edouard Herriot Hospital (Lyon, France) in November 2012. An 87-year-old women was hospitalized in the geriatric unit between August 31 and October 1, 2012, because of hip fracture. A urinary tract infection, caused by New Delhi metallo-b-lactamase (NDM-1)-producing Escherichia coli, was diagnosed 10 days after hospital discharge. According to French recommendations (Haut Conseil de la Santé Publique), patients hospitalized in the unit at the same time were listed and screened for CPE carriage. No secondary case was diagnosed. The investigation found no evidence of travel history of the patient and her relatives in the 6 months before hospitalization. A standardized, self-administrated questionnaire was proposed to HCWs of the geriatric unit. The requested information concerned the countries visited less than 6 months before the investigation, the travel dates, and the reasons for travel. Countries were categorized by geographic zone and defined as at risk of CPE or NDM-1 CPE if at least 2 CPE or NDM-1 CPE episodes in relation to a particular country were respectively reported to the French Institute for Public Health Surveillance on October 3, 2012. The response rate was 76%: 32 (68%) paramedical and 20 (95%) medical personnel answered, and their responses were analyzed. Overall, 38% (n1⁄4 20, 95% confidence interval: 26%-52%) of the HCWs travelled in 19 different countries in the 6 months before the investigation. ThirteenHCWs travelled in 1 foreign country, 6 in 2 different countries, and 1 in 3 different countries. Twenty-eight trips were

Contacts between health care workers and patients in a short-stay geriatric unit during the peak of a seasonal influenza epidemic compared with a nonepidemic period

BACKGROUND Patterns of contacts between health care workers and patients during seasonal epidemics are unknown. Our study objective was to compare the number and duration of contacts between health care workers and patients during a nonepidemic period versus a community influenza epidemic, and to identify supercontactors. METHODS Our observational study was conducted in a short-stay geriatric unit of a university hospital. Contacts between individuals were recorded by active radio frequency identification devices. Contact patterns were compared between 2 periods according to contact number and duration. Each care period lasted 5 days in the nonepidemic and influenza epidemic periods. RESULTS The study included 21 medical doctors, 43 nurses, and 56 patients. In total, 3,200 contacts (61.4%; 152,700 seconds) were recorded during the nonepidemic period, with 2,013 contacts (38.6%; 92,740 seconds) in the epidemic period (P = .007). More cumulative contacts occurred during the nonepidemic period between nurses and patients (n = 2,638 [82%] vs n = 1,599 [79%]), but not between patients (n = 56 [18%] vs n = 414 [21%]). Contact duration between nurses and patients lasted longer during the nonepidemic period (P = .04). During the epidemic period, 6 nurses (15%) considered to be supercontactors accounted for 44.3% of the total number of contacts with patients. CONCLUSION The pattern of contacts between individuals differed according to the presence or not of the community influenza peak that might have influenced the risk of nosocomial influenza.