Nosocomial Transmission Of Influenza Research Articles

Influenza transmissibility among patients and health-care professionals in a geriatric short-stay unit using individual contact data

Detailed information are lacking on influenza transmissibility in hospital although clusters are regularly reported. In this pilot study, our goal was to estimate the transmission rate of H3N2 2012-influenza, among patients and health care professionals in a short-term Acute Care for the Elderly Unit by using a stochastic approach and a simple susceptible-exposed-infectious-removed model. Transmission parameters were derived from documented individual contact data collected by Radio Frequency IDentification technology at the epidemic peak. From our model, nurses appeared to transmit infection to a patient more frequently with a transmission rate of 1.04 per day on average compared to 0.38 from medical doctors. This transmission rate was 0.34 between nurses. These results, even obtained in this specific context, might give a relevant insight of the influenza dynamics in hospitals and will help to improve and to target control measures for preventing nosocomial transmission of influenza. The investigation of nosocomial transmission of SARS-COV-2 might gain from similar approaches.

Nosocomial influenza in a pediatric general ward: Effects of isolation and cohort placement of children with influenza.

Many studies have described nosocomial outbreaks of influenza in specialized wards. We evaluated nosocomial transmission of influenza in a pediatric general ward. Retrospective observational study. Single secondary hospital. The study included 814 hospitalized children with influenza between September 2015 and August 2020. The medical records of the included children were retrospectively reviewed, and clinical characteristics of children with community-acquired (CA) influenza and hospital-acquired (HA) influenza were determined. The room of each included child during hospitalization was traced to identify the children exposed to them. CA influenza and HA influenza were diagnosed in 789 (96.9%) and 25 (3.1%) children, respectively. Among children with CA influenza, 691 (87.6%) were isolated or place in a cohort on admission. In total, 98 children (12.4%) admitted to multibed rooms exposed 307 children with noninfluenza diseases to influenza during 772 patient days; 3 exposed children (1.0%) were diagnosed with HA influenza. Including these 3 children, 25 children (19 without definite in-hospital exposure to influenza and 3 exposed to other children with HA influenza) were diagnosed with HA influenza, and 11 (44.0%) exposed 31 children with noninfluenza diseases to influenza for 85 patient days. Also, 3 exposed children (9.7%) were diagnosed with HA influenza, a significantly higher rate than that for CA influenza (P = .005). The clinical characteristics were comparable between children with HA influenza and those with CA influenza. Cohort placement of children with influenza in a pediatric general ward can be effective in controlling nosocomial transmission of influenza. However, control measures for children with HA influenza should be emphasized.

Influenza Vaccination Coverage, Motivators for, and Barriers to Influenza Vaccination among Healthcare Workers in Wroclaw, Poland.

Background: Influenza vaccination, as a key element of control activities intended to prevent nosocomial influenza transmission, is recommended each year for all healthcare workers (HCWs). The objectives were to determine the rate of influenza vaccination and to identify reasons for receiving or declining the influenza vaccine among HCWs in the 2018/19 and 2019/20 influenza seasons. Methods: This study is a cross-sectional observational study carried out between January and March 2020, in 2 hospitals and 15 primary health-care settings (PHCS) in Wroclaw (Poland). Results: A total of 165 questionnaires were completed. The majority of participating HCWs were female—137 (83.0%), and, by profession, the majority were physicians 92 (55.8%). Influenza vaccination coverage was 61.2% in 2019/20, and 47.9% in the 2018/19 season for all participants. Participants who were male, physicians and personnel from PHCS were more frequently vaccinated in both seasons. According to the statistical analysis, physicians were more likely to receive vaccinations than nurses (p < 0.01), as were HCWs who had been vaccinated in the previous season (p < 0.001). Conclusion: The identified barriers were mainly caused by misconceptions (fear of vaccine adverse effects and perception of not being at risk/no need to get vaccinated) and an organizational barriers (lack of time). These findings may prove useful for designing immunization campaigns to tailor strategies to reach specific groups.

Secondary attack rates from asymptomatic and symptomatic influenza virus shedders in hospitals: Results from the TransFLUas influenza transmission study.

Nosocomial transmission of influenza is a major concern for infection control. We aimed to dissect transmission dynamics of influenza, including asymptomatic transmission events, in acute care. Prospective surveillance study during 2 influenza seasons. Tertiary-care hospital. Volunteer sample of inpatients on medical wards and healthcare workers (HCWs). Participants provided daily illness diaries and nasal swabs for influenza A and B detection and whole-genome sequencing for phylogenetic analyses. Contacts between study participants were tracked. Secondary influenza attack rates were calculated based on spatial and temporal proximity and phylogenetic evidence for transmission. In total, 152 HCWs and 542 inpatients were included; 16 HCWs (10.5%) and 19 inpatients (3.5%) tested positive for influenza on 109 study days. Study participants had symptoms of disease on most of the days they tested positive for influenza (83.1% and 91.9% for HCWs and inpatients, respectively). Also, 11(15.5%) of 71 influenza-positive swabs among HCWs and 3 (7.9%) of 38 influenza-positive swabs among inpatients were collected on days without symptoms; 2 (12.5%) of 16 HCWs and 2 (10.5%) of 19 inpatients remained fully asymptomatic. The secondary attack rate was low: we recorded 1 transmission event over 159 contact days (0.6%) that originated from a symptomatic case. No transmission event occurred in 61 monitored days of contacts with asymptomatic influenza-positive individuals. Influenza in acute care is common, and individuals regularly shed influenza virus without harboring symptoms. Nevertheless, both symptomatic and asymptomatic transmission events proved rare. We suggest that healthcare-associated influenza prevention strategies that are based on preseason vaccination and barrier precautions for symptomatic individuals seem to be effective.

Incidence of Asymptomatic and Symptomatic Influenza Among Healthcare Workers: A Multicenter Prospective Cohort Study.

Influenza is an important cause of viral hospital-acquired infection involving patients, healthcare workers (HCW), and visitors. The frequency of asymptomatic influenza among HCW with possible subsequent transmission is poorly described. The objective is to determine the cumulative incidence of asymptomatic, paucisymptomatic, and symptomatic influenza among HCW. A multicenter prospective cohort study was done in 5 French university hospitals, including 289 HCW during the 2016-2017 influenza season. HCW had 3 physical examinations (time [T] 0, before epidemic onset; T.1, before epidemic peak; T.2, T.3, after epidemic peak). A blood sample was taken each time for influenza serology and a nasal swab was collected at T1 and T2 for influenza detection by polymerase chain reaction (PCR). Positive influenza was defined as either a positive influenza PCR, and/or virus-specific seroconversion against influenza A, the only circulating virus, with no vaccination record during follow-up. Symptoms were self-reported daily between T1 and T2. Cumulative incidence of influenza was stratified by clinical presentation per 100 HCW. Of the 289 HCW included, 278 (96%) completed the entire follow-up. Overall, 62 HCW had evidence of influenza of whom 46.8% were asymptomatic, 41.9% were paucisymptomatic, and 11.3% were symptomatic. Cumulative influenza incidence was 22.3% (95% confidence interval [CI]: 17.4%-27.2%). Cumulative incidence of asymptomatic influenza was 5.8% (95% CI: 3.3%-9.2%), 13.7% (95% CI: 9.9%-18.2%) for paucisymptomatic influenza, and 2.9% (95% CI: 1.3%-5.5%) for symptomatic influenza. Asymptomatic and paucisymptomatic influenza were frequent among HCW, representing 47% and 42% of the influenza burden, respectively. These findings highlight the importance of systematic implementation of infection control measures among HCW regardless of respiratory symptoms from preventing nosocomial transmission of influenza. NCT02868658.

Five-Day vs 10-Day Postexposure Chemoprophylaxis With Oseltamivir to Prevent Hospital Transmission of Influenza: A Noninferiority Randomized Open-Label Study.

BackgroundThe efficacy and optimal duration of postexposure influenza prophylaxis with oseltamivir are undetermined in hospital settings, where immediate separation from index cases is not feasible.MethodsIn an open-label noninferiority randomized clinical trial in a single-center university hospital, the efficacy of 5-day vs 10-day postexposure prophylaxis with oseltamivir was compared in adult patients exposed to influenza who could not be immediately separated from index influenza cases. Influenza incidence was assessed for 10 days after discontinuing prophylaxis.ResultsAmong 222 exposed patients (median age, 75 years; male 119; median Charlson Comorbidity Index, 5), 110 patients were assigned to 5 days of postexposure prophylaxis with oseltamivir, and 112 patients were assigned to the 10-day group. The median duration of exposure to influenza (interquartile range) was 2 (1–3) days. In the intention-to-treat analysis, the incidence of influenza was 2/110 (1.8%) in the 5-day group and 0/112 (0%) in the 10-day group (difference, 1.8 percentage points; 1-sided 95% CI, –1 to 4.9 percentage points; P = .77).ConclusionsFor patients exposed to influenza in a hospital setting and who were not immediately separated from index cases, postexposure prophylaxis with oseltamivir resulted in low incidence of nosocomial influenza transmission. Five-day postexposure prophylaxis was noninferior to 10-day regimen.ClinicalTrials.gov RegistrationNCT03899571.

Rapid Point-of-Care Influenza Testing for Patients in German Emergency Rooms - A Cost-Benefit Analysis.

BackgroundEach year, influenza causes significant morbidity and death worldwide and produces significant economic losses at the expense of the healthcare system.ObjectiveTo assess the cost-benefit relationship of implementing a rapid point-of-care (POC) influenza test in emergency rooms (ERs) of German hospitals.MethodsA deterministic decision-analytic model simulated the incremental costs of using the Sofia® Influenza A+B test compared to those of using clinical judgement alone to confirm or exclude influenza in adult ILI (influenza-like illness) patients in German ERs prior to hospitalization. Direct costs, with and without subsequent oseltamivir treatment, were evaluated from the hospital perspective as well as indirect costs incurred by nosocomial influenza transmission to hospital employees.ResultsIn base-case analysis, taking the influenza prevalence of 25.9% in the season 2018/2019 and assuming a hospitalization rate among influenza suspects of 21.9%, rapid testing with the Sofia® followed by administering oseltamivir to patients testing positive reduced average costs of hospitalized ILI patients by €52.16 per tested patient. If oseltamivir was not offered, testing with the Sofia® reduced costs by €42.28 in favor of the hospital.In probabilistic sensitivity analysis, under all reasonable assumptions, implementing the Sofia® saved on average €119.89 as compared to applying the clinical-judgement-only strategy. The major part of the cost savings, €113.17 or 94.4%, was due to the POC test’s high specificity, which led to 91% reduction in needless bed-blocking on the first day of hospitalization. However, as the sensitivity of 75.3% was only slightly higher than that of conventional clinical judgement, improved classification of patients with true influenza and a correspondingly lower rate of illness in hospital employees could not be achieved.ConclusionsUsing highly specific rapid POC influenza tests in ILI patients at German ER, despite their sub-optimal sensitivity, may significantly reduce hospital expenditures.

Diel R, Nienhaus A. Rapid Point-of-Care Influenza Testing for Patients in German Emergency Rooms – A Cost-Benefit Analysis

Background: Each year, influenza causes significant morbidity and death worldwide and produces significant economic losses at the expense of the healthcare system. Objective: To assess the cost-benefit relationship of implementing a rapid point-of-care (POC) influenza test in emergency rooms (ERs) of German hospitals. Methods: A deterministic decision-analytic model simulated the incremental costs of using the Sofia® Influenza A+B test compared to those of using clinical judgement alone to confirm or exclude influenza in adult ILI (influenza-like illness) patients in German ERs prior to hospitalization. Direct costs, with and without subsequent oseltamivir treatment, were evaluated from the hospital perspective as well as indirect costs incurred by nosocomial influenza transmission to hospital employees. Results: In base-case analysis, taking the influenza prevalence of 25.9% in the season 2018/2019 and assuming a hospitalization rate among influenza suspects of 21.9%, rapid testing with the Sofia® followed by administering oseltamivir to patients testing positive reduced average costs of hospitalized ILI patients by €52.16 per tested patient. If oseltamivir was not offered, testing with the Sofia® reduced costs by €42.28 in favor of the hospital. In probabilistic sensitivity analysis, under all reasonable assumptions, implementing the Sofia® saved on average €119.89 as compared to applying the clinical-judgement-only strategy. The major part of the cost savings, €113.17 or 94.4%, was due to the POC test´s high specificity, which led to 91% reduction in needless bed-blocking on the first day of hospitalization. However, as the sensitivity of 75.3% was only slightly higher than that of conventional clinical judgement, improved classification of patients with true influenza and a correspondingly lower rate of illness in hospital employees could not be achieved. Conclusions: Using highly specific rapid POC influenza tests in ILI patients at German ER, despite their sub-optimal sensitivity, may significantly reduce hospital expenditures.

Nosocomial transmission of influenza: A retrospective cross-sectional study using next generation sequencing at a hospital in England (2012-2014).

BackgroundThe extent of transmission of influenza in hospital settings is poorly understood. Next generation sequencing may improve this by providing information on the genetic relatedness of viral strains.ObjectivesWe aimed to apply next generation sequencing to describe transmission in hospital and compare with methods based on routinely‐collected data.MethodsAll influenza samples taken through routine care from patients at University College London Hospitals NHS Foundation Trust (September 2012 to March 2014) were included. We conducted Illumina sequencing and identified genetic clusters. We compared nosocomial transmission estimates defined using classical methods (based on time from admission to sample) and genetic clustering. We identified pairs of cases with space‐time links and assessed genetic relatedness.ResultsWe sequenced influenza sampled from 214 patients. There were 180 unique genetic strains, 16 (8.8%) of which seeded a new transmission chain. Nosocomial transmission was indicated for 32 (15.0%) cases using the classical definition and 34 (15.8%) based on genetic clustering. Of the 50 patients in a genetic cluster, 11 (22.0%) had known space‐time links with other cases in the same cluster. Genetic distances between pairs of cases with space‐time links were lower than for pairs without spatial links (P < .001).ConclusionsGenetic data confirmed that nosocomial transmission contributes significantly to the hospital burden of influenza and elucidated transmission chains. Prospective next generation sequencing could support outbreak investigations and monitor the impact of infection and control measures.

Cost-Benefit Analysis of Real-Time Influenza Testing for Patients in German Emergency Rooms.

Background: Seasonal influenza causes significant morbidity worldwide and has a substantial economic impact on the healthcare system. Objective: To assess the cost–benefit relation of implementing a real-time influenza test in emergency rooms (ER) of German hospitals. Methods: A deterministic decision-analytic model was developed simulating the incremental costs of using the Solana® Influenza A+B test, compared to those of using conventional clinical judgement alone to confirm or exclude influenza in adult ILI (influenza-like illness) patients, in German ER, prior to hospitalization. Direct costs were evaluated from the hospital perspective, considering resource use directly related to influenza testing and treatment, as well as indirect costs incurred by nosocomial influenza transmission. Results: Through base-case analysis and assuming an influenza prevalence of 42.6%, real-time testing with Solana® reduced average costs of hospitalized ILI patients by €132.61, per tested patient. Moreover, the Solana® saved €6.9 per tested patient in favor of the hospital. In probabilistic sensitivity analysis, under all reasonable assumptions, implementing the Solana® saved on average €144.13 as compared to applying the clinical-judgement-only strategy, thus, it was found to be constantly less expensive. Conclusions: Using highly sensitive and specific real-time influenza tests in ILI patients at German ER might significantly reduce hospital expenditures

Implementation of influenza point-of-care testing and patient cohorting during a high-incidence season: a retrospective analysis of impact on infection prevention and control and clinical outcomes

During high-incidence influenza seasons, a robust infection prevention and control policy is imperative to reduce nosocomial transmission of influenza. To assess the impact of influenza point-of-care testing (POCT) in an emergency department (ED) and patient cohorting on an influenza ward on infection prevention and control and clinical outcomes. Influenza POCT was operational in the study ED from 21st January 2018 and patient cohorting was operational on an influenza ward from 25th January 2018. A retrospective 'before-after' analysis was performed with pre-intervention defined as 1st November 2017 to 20th January 2018 and post-intervention defined as 21st January 2018 to 30th April 2018. The primary outcome was the rate of hospital-acquired influenza. Secondary outcomes included antiviral prescription and length of stay. The length of time that inpatients remained influenza-positive was estimated by polymerase chain reaction (PCR). There were 654 inpatients with confirmed influenza during the 2017/18 influenza season: 223 pre- and 431 post-intervention. Post-intervention, there were fewer cases of hospital-acquired influenza per day (0.66 vs 0.95, P<0.0001), median length of stay was shorter (5.5 vs 7.5 days, P=0.005) and antiviral prescription was more frequent (80% vs 64.1%, P<0.0001). Cohorting released 779 single rooms for use elsewhere in the trust. The fixed probability of being PCR-negative by the next day (P) was 0.14 [95% confidence interval (CI) 0.12-0.16] for immunocompetent patients. This implies that half of immunocompetent patients are PCR-negative by five days post-diagnosis (95% CI 5-6). Influenza POCT in an ED and patient cohorting on an influenza ward were associated with reduced nosocomial transmission of influenza and improved patient flow. A policy of retesting immunocompetent patients five days post-diagnosis could allow half of these patients to come out of respiratory isolation earlier.

Use of Whole-Genome Sequencing in the Investigation of a Nosocomial Influenza Virus Outbreak.

Traditional epidemiological investigation of nosocomial transmission of influenza involves the identification of patients who have the same influenza virus type and who have overlapped in time and place. This method may misidentify transmission where it has not occurred or miss transmission when it has. We used influenza virus whole-genome sequencing (WGS) to investigate an outbreak of influenza A virus infection in a hematology/oncology ward and identified 2 separate introductions, one of which resulted in 5 additional infections and 79 bed-days lost. Results from WGS are becoming rapidly available and may supplement traditional infection control procedures in the investigation and management of nosocomial outbreaks.

Estudio actitudes sobre vacunación antigripal en profesionales sanitarios de atención primaria de Cataluña

ObjectiveHealth personnel are at risk of acquiring influenza infection and of nosocomial influenza transmission. The objective of this study was to assess the relationship between the knowledge and attitudes of primary care health personnel in Catalonia as regards influenza vaccine and the factors related to the uptake of this vaccine. DesignA cross-sectional study using a web survey. SettingPrimary care health personnel of the Catalan Health Institute. ParticipantsA total of 1212 primary health care personnel were included in the survey. Those who had medical reasons for being or not being vaccinated were excluded. ResultsA total of 423 replies were valid, with a 46.6% overall vaccination coverage. Vaccination rate was higher among 45 to 54 year-olds, paediatricians, those vaccinated in preceding seasons, and those living with chronic patients. There was an association between having received the vaccine and considering vaccination the best preventive action, advocating vaccination to at risk population, concern about acquiring influenza, and considering health personnel vaccination important. ConclusionsActions taken to increase vaccination rate among health personnel should aim at correcting lack of knowledge and misconceptions about influenza vaccination of health personnel.

Transmission and effect of multiple clusters of seasonal influenza in a Swiss geriatric hospital.

ObjectivesTo investigate a nosocomial outbreak of influenza.DesignProspective outbreak investigation with active case finding and molecular typing.SettingA large academic geriatric hospital in Switzerland.ParticipantsElderly hospitalized adults.MeasurementsBased on syndromic surveillance, a nosocomial influenza outbreak was suspected in February 2012. All suspected cases were screened for respiratory viruses using real‐time reverse transcription polymerase chain reaction of nasopharyngeal swabs. Infection control procedures (droplet precautions with single room isolation whenever possible) were implemented for all suspected or confirmed cases. Specimens positive for influenza viruses were processed and sequenced whenever possible to track transmission dynamics.ResultsRespiratory samples from 155 suspected cases were analyzed during the outbreak period, of which 69 (44%) were positive for influenza virus, 26 (17%) were positive for other respiratory viruses, and 60 (39%) were negative. Three other cases fulfilled clinical criteria for influenza infection but were not sampled, and one individual was admitted with an already positive test, resulting in a total of 73 influenza cases, of which 62 (85%) were classified as nosocomial. Five distinct clusters of nosocomial transmission were identified using viral sequencing, with epidemiologically unexpected in‐hospital transmission dynamics. Seven of 23 patients who experienced influenza complications died. Sixteen healthcare workers experienced an influenza‐like illness (overall vaccination rate, 36%).ConclusionNosocomial influenza transmission caused more secondary cases than repeated community importation during this polyclonal outbreak. Molecular tools revealed complex transmission dynamics. Low healthcare worker vaccination rates and gaps in recommended infection control procedures are likely to have contributed to nosocomial spread of influenza, which remains a potentially life‐threatening disease in elderly adults.

An Ethical Analysis of Mandatory Influenza Vaccination of Health Care Personnel: Implementing Fairly and Balancing Benefits and Burdens

Health care institutions have paid increasing attention to preventing nosocomial transmission of influenza through vaccination of health care personnel. While multifaceted voluntary interventions have increased vaccination rates, proponents of mandatory programs contend the rates remain unacceptably low. Conventional bioethical analyses of mandatory programs are inadequate; they fail to account for the obligations of nonprofessional personnel or to justify the weights assigned to different ethical principles. Using an ethics framework for public health permits a fuller analysis. The framework's focus on fairness accentuates the potential differences between the risk of transmitting infection and employment status, and the need to equitably evaluate exemptions. The framework's emphasis on balancing benefits and burdens highlights the need to justify a specific goal and questions the need to exclude all nonmedical exemptions. While mandatory vaccination programs are justifiable, greater attention should be paid to their implementation.

P039: A new method to assess compliance with measures to prevent nosocomial influenza transmission

Seasonal influenza (SI) can present a serious threat to some patients, particularly those with underlying diseases. Healthcare workers (HCW) should use appropriate means to prevent influenza transmission in healthcare settings, with vaccination considered as the most important recommended measure. At our institution, a significant proportion of HCWs refuse vaccination. As an alternative solution to protect patients from SI, HCWs at our hospital are now obliged to be vaccinated or wear masks during SI epidemics. We propose a method for the quantification of adherence to this recommendation.

Pandemic A(H1N1)2009 influenza vaccination in Lyon University Hospitals, France: Perception and attitudes of hospital workers

Health-care authorities encouraged A(H1N1)2009 influenza vaccination for all hospital workers because of their high risk of contracting and transmitting the virus.Six months after the vaccination campaign began, an electronic anonymous questionnaire was completed by 1630 among 14,000 hospital workers (11.6%). Vaccination rate was 54.3%. Independent predictors for vaccination acceptance were advanced age (OR=1.61–2.19), being a physician (OR=5.07), working in gynaecology-obstetrics or podiatry (OR=1.62), and having been informed about vaccination (OR=2.78). The main reasons for getting vaccinated were to avoid flu for relatives (82.4%), themselves (65.8%) and patients (57.1%). Arguments against vaccination were lack of sufficient studies of the vaccine (75.7%) and the perception of A(H1N1)2009 influenza as a benign disease (51.5%).Vaccination coverage would be insufficient to keep the health-care system operating at maximum capacity during a severe pandemic disease, and to avoid nosocomial transmission of influenza. These results suggest a better-targeted vaccination campaign.

Sequence-based identification and characterization of nosocomial influenza A(H1N1)pdm09 virus infections

Highly transmissible viruses such as influenza are a potential source of nosocomial infections and thereby cause increased patient morbidity and mortality. To assess whether influenza virus sequence data can be used to link nosocomial influenza transmission between individuals. Dutch A(H1N1)pdm09-positive specimens from one hospital (N = 107) were compared with samples from community cases (N = 685). Gene fragments of haemagglutinin, neuraminidase and PB2 were sequenced and subsequently clustered to detect patients infected with identical influenza viruses. The probability of detecting a second patient was calculated for each hospital cluster against the background diversity observed in hospital and community strains. All clusters were further analysed for possible links between patients. Seventeen A(H1N1)pdm09 hospital clusters were detected of which eight had a low probability of occurrence compared with background diversity (P < 0.01). Epidemiological analysis confirmed a total of eight nosocomial infections in four of these eight clusters, and a mother-child combination in a fifth cluster. The nine clusters with a high probability of occurrence involved community cases of influenza without a known epidemiological link. If a background sequence dataset is available, the detection of hospital sequence clusters that differ from dominant community strains can be used to select clusters requiring further investigation by hospital hygienists before a nosocomial influenza outbreak is epidemiologically suspected.

Changes in influenza vaccination rates among healthcare workers following a pandemic influenza year at a Japanese tertiary care centre

Although influenza vaccination, which is a key part of a control plan to prevent nosocomial influenza transmission, is recommended for all healthcare workers (HCWs), the achievement of a high influenza vaccination rate among HCWs is a challenge. In Japan, there are limited data on influenza vaccination rates among HCWs. Moreover, the effect of pandemic influenza on influenza vaccination rates among HCWs following a pandemic year remains unclear. To determine influenza vaccination rates among HCWs at a tertiary medical centre in Japan, and to evaluate the need for further interventions to enhance the vaccination rate among HCWs. The 2005-2010 influenza vaccination rates among HCWs at a 550-bed, tertiary care centre in Sapporo, Japan were reviewed retrospectively using the hospital's occupational health service database. There was a gradual increase in the seasonal influenza vaccination rate in this population from 2005 to 2010, and a high vaccination rate among HCWs during the 2009-2010 pandemic H1N1 influenza season. However, the seasonal influenza vaccination rate in 2010-2011 was significantly lower than that for the pandemic vaccine in 2009-2010, with doctors having the lowest vaccination rate among all HCWs. Pandemic influenza may not have a sustained effect on the uptake of influenza vaccination in subsequent years. Thus, vaccination rates among HCWs after a pandemic year still need to be monitored, and the implementation of interventions such as a mandatory vaccination programme should be considered to maintain consistently adequate vaccination rates.

An outbreak of the 2009 influenza a (H1N1) virus in a children’s hospital

Please cite this paper as: Bearden et al. (2012) An outbreak of the 2009 influenza a (H1N1) virus in a children’s hospital. Influenza and Other Respiratory Viruses 6(5), 374–379. Context Preventing nosocomial transmission of influenza is essential to reduce the morbidity and mortality associated with this infection. In October 2009, an outbreak of the 2009 influenza A (H1N1) virus occurred in a hematology ward of a children’s hospital over a 21‐day period and involved two patients and four healthcare workers. Objective To investigate nosocomial transmission of the 2009 influenza A (H1N1) virus in patients and healthcare workers. Design, setting, and participants An outbreak investigation was initiated in response to suspected nosocomial transmission of the 2009 influenza A (H1N1) virus during the peak of the 2009 pandemic. Cases were confirmed using a polymerase chain reaction (PCR) test specific for the 2009 H1N1 influenza A virus. Viruses isolated from nasopharyngeal swabs were genetically characterized using Sanger sequencing of uncloned “bulk” PCR products. Main outcome measures Virus sequencing to investigate nosocomial transmission. Results Two immunocompromised patients and four healthcare workers were found to be part of a nosocomial outbreak of the 2009 influenza A (H1N1) virus. One immunocompromised patient had a second episode of clinical influenza infection after isolation precautions had been discontinued, resulting in additional exposures. Strain‐specific PCR showed that all cases were caused by infection of the 2009 H1N1 virus. Sequencing of viral genes encoding hemagglutinin and polymerase basic subunit 2 (PB2) revealed that all viruses isolated were genetically identical at these loci, including the two episodes occurring in the same immunocompromised patient. Conclusions Prompt institution of isolation precautions is essential in preventing nosocomial outbreaks of the 2009 novel influenza A (H1N1) virus. Our data suggest that isolation precautions may need to be continued for a prolonged period of time in immunocompromised patients with influenza infection.