The use of antiviral drugs for influenza: Guidance for practitioners 2012/2013

Torsades De Pointes Electrical Storm Induced by H1N1 in a Patient with KCNH2 Variant of Unknown Significance

This report describes a case of an electrical storm of Torsades De Pointes in a structurally normal heart, following an H1N1 infection in the presence of a genetic variant of unknown significance. The patient was successfully treated with isoproterenol. This case highlights the dilemma of evaluating novel genetic testing results in a clinical setting.

The Central Role of Non-Structural Protein 1 (NS1) in Influenza Biology and Infection

Influenza (flu) is a contagious viral disease, which targets the human respiratory tract and spreads throughout the world each year. Every year, influenza infects around 10% of the world population and between 290,000 and 650,000 people die from it according to the World Health Organization (WHO). Influenza viruses belong to the Orthomyxoviridae family and have a negative sense eight-segment single-stranded RNA genome that encodes 11 different proteins. The only control over influenza seasonal epidemic outbreaks around the world are vaccines, annually updated according to viral strains in circulation, but, because of high rates of mutation and recurrent genetic assortment, new viral strains of influenza are constantly emerging, increasing the likelihood of pandemics. Vaccination effectiveness is limited, calling for new preventive and therapeutic approaches and a better understanding of the virus-host interactions. In particular, grasping the role of influenza non-structural protein 1 (NS1) and related known interactions in the host cell is pivotal to better understand the mechanisms of virus infection and replication, and thus propose more effective antiviral approaches. In this review, we assess the structure of NS1, its dynamics, and multiple functions and interactions, to highlight the central role of this protein in viral biology and its potential use as an effective therapeutic target to tackle seasonal and pandemic influenza.

Effectiveness of Influenza Vaccination on Hospitalizations and Risk Factors for Severe Outcomes in Hospitalized Patients With COPD

BACKGROUND

The effectiveness of influenza vaccination in reducing influenza-related hospitalizations among patients with COPD is not well described, and influenza vaccination uptake remains suboptimal.

METHODS

Data were analyzed from a national, prospective, multicenter cohort study including patients with COPD, hospitalized with any acute respiratory illness or exacerbation between 2011 and 2015. All patients underwent nasopharyngeal swab screening with polymerase chain reaction (PCR) testing for influenza. The primary outcome was an influenza-related hospitalization. We identified influenza-positive cases and negative control subjects and used multivariable logistic regression with a standard test-negative design to estimate the vaccine effectiveness for preventing influenza-related hospitalizations.

RESULTS

Among 4,755 hospitalized patients with COPD, 4,198 (88.3%) patients with known vaccination status were analyzed. The adjusted analysis showed a 38% reduction in influenza-related hospitalizations in vaccinated vs unvaccinated individuals. Influenza-positive patients (n = 1,833 [38.5%]) experienced higher crude mortality (9.7% vs 7.9%; P = .047) and critical illness (17.2% vs 12.1%; P < .001) compared with influenza-negative patients. Risk factors for mortality in influenza-positive patients included age > 75 years (OR, 3.7 [95% CI, 0.4-30.3]), cardiac comorbidity (OR, 2.0 [95% CI, 1.3-3.2]), residence in long-term care (OR, 2.6 [95% CI, 1.5-4.5]), and home oxygen use (OR, 2.9 [95% CI, 1.6-5.1]).

CONCLUSIONS

Influenza vaccination significantly reduced influenza-related hospitalization among patients with COPD. Initiatives to increase vaccination uptake and early use of antiviral agents among patients with COPD could reduce influenza-related hospitalization and critical illness and improve health-care costs in this vulnerable population.

TRIAL REGISTRY

ClinicalTrials.govNo.:NCT01517191; URL www.clinicaltrials.gov.

Influenza burden, prevention, and treatment in asthma-A scoping review by the EAACI Influenza in asthma task force

To address uncertainties in the prevention and management of influenza in people with asthma, we performed a scoping review of the published literature on influenza burden; current vaccine recommendations; vaccination coverage; immunogenicity, efficacy, effectiveness, and safety of influenza vaccines; and the benefits of antiviral drugs in people with asthma. We found significant variation in the reported rates of influenza detection in individuals with acute asthma exacerbations making it unclear to what degree influenza causes exacerbations of underlying asthma. The strongest evidence of an association was seen in studies of children. Countries in the European Union currently recommend influenza vaccination of adults with asthma; however, coverage varied between regions. Coverage was lower among children with asthma. Limited data suggest that good seroprotection and seroconversion can be achieved in both children and adults with asthma and that vaccination confers a degree of protection against influenza illness and asthma-related morbidity to children with asthma. There were insufficient data to determine efficacy in adults. Overall, influenza vaccines appeared to be safe for people with asthma. We identify knowledge gaps and make recommendations on future research needs in relation to influenza in patients with asthma.

Increase in Hospital Admissions for Severe Influenza A/B among Travelers on Cruise Ships to Alaska, 2015

An increase in hospital admissions for influenza occurred during the summer of 2015 at an acute care facility in Vancouver, British Columbia, Canada. Investigation identified 25 patients with recent history of cruise ship travel to Alaska. All characterized influenza A viruses were A(H3N2). We describe patient treatment regimens and outcomes.

Effectiveness of seasonal influenza vaccination in patients with diabetes: protocol for a nested case-control study

INTRODUCTION

Seasonal influenza vaccination (SIV) is recommended for people with diabetes, but its effectiveness has not been demonstrated. All of the available studies are observational and marred with the healthy vaccine bias, that is, bias resulting from the generally better health behaviours practised by people who choose to be vaccinated against influenza, compared with those who do not. This protocol is intended to study the effectiveness of SIV in people with treated diabetes and simultaneously to control for bias.

METHODS AND ANALYSES

This case-control study is nested in a historical cohort and is designed to study vaccine effectiveness (VE) assessed by morbidity, mortality and anti-infective drug use. The cohort will comprise a representative sample of health insurance beneficiaries in France and will cover 10 consecutive epidemic seasons. It will include all patients reimbursed three separate times for drugs to treat diabetes. The first study of VE will use reasons for hospitalisation as the primary end point, and the second with the use of neuraminidase inhibitors and of antibiotics as the end points. A case will be defined as any person in the cohort reaching any end point at a given date. The case patient will be matched with the largest possible number of controls (individuals not reaching the end point by this date) according to the propensity score method with an optimal calliper width. A conditional logistic model will be used to estimate ORs to take into account both the matching and the repetition of measurements. The model will be applied separately during and outside of epidemic periods to estimate the residual confounding.

ETHICS AND DISSEMINATION

The study has been approved by the French Commission on Individual Data Protection and Public Liberties (ref: AT/CPZ/SVT/JB/DP/CR05222O). The study's findings will be published in peer-reviewed journals and disseminated at international conferences and through social media.

Influenza outbreak in a Canadian correctional facility

Correctional facilities face increased risk of communicable disease transmission and outbreaks. We describe the progression of an influenza outbreak in a Canadian remand facility and suggest strategies for preventing, identifying and responding to outbreaks in this setting. In total, six inmates had laboratory-confirmed influenza resulting in 144 exposed contacts. Control measures included enhanced isolation precautions, restricting admissions to affected living units, targeted vaccination and antiviral prophylaxis. This report highlights the importance of setting specific outbreak guidelines in addressing population and environmental challenges, as well as implementation of effective infection prevention and control (IPAC) and public health measures when managing influenza and other communicable disease outbreaks.

Pre-and post-pandemic trends in antiviral use in hospitalized patients with laboratory-confirmed influenza: 2004/05-2013/14, Toronto, Canada

BACKGROUND

Data on factors associated with the use of antiviral medication to treat influenza in both children and adults are limited.

OBJECTIVES

To describe trends in antiviral use, analyze factors associated with antiviral treatment of hospitalized patients with influenza, and to compare use based on guidelines.

STUDY DESIGN

A retrospective observational cohort of hospitalized patients with laboratory confirmed influenza in southern Ontario hospitals for the 2004/05-2013/14 seasons.

RESULTS

Of the 7967 patients, 18% of the 1779 children (<15 years) and 66% of the 6188 adults received antiviral therapy. The percentage treated increased from 29% pre-pandemic to 74% during the pandemic, decreased to 55% in 2011/12 and then increased to 65% in 2013/14. Factors significantly associated with antiviral prescription across all age groups during the non-pandemic seasons include influenza type, disease severity, interval between symptom onset and test sample submission, and clinician suspicion of influenza. Rate of treatment of patients meeting guideline criteria was low for children and moderate for adults.

CONCLUSIONS

Since the pandemic, there has been a sustained increase in the use of antiviral medication for all age groups of hospitalized patients with influenza, but much higher for adults than children. The odds of treatment are higher for patients with more severe disease as well as for those tested within 48 h of symptom onset, both of which are part of the guidelines for treatment with anti-influenza medications.

Evaluation of the use of oseltamivir prophylaxis in the control of influenza outbreaks in long-term care facilities in Alberta, Canada: a retrospective provincial database analysis

OBJECTIVES

To evaluate the impact of oseltamivir prophylaxis in the management and control of influenza outbreaks in long-term care facilities in Alberta, Canada.

SETTING AND PARTICIPANTS

Long-term care facilities where 127 influenza outbreaks were reported to public health authorities in Alberta, Canada, during two influenza seasons from 2013 to 2015.

DESIGN AND OUTCOME MEASURES

Using routinely collected surveillance and administrative data, we examined the association between decision-making time for oseltamivir recommendation as prophylaxis strategy for influenza outbreaks in long-term care facilities (explanatory variable) and the duration of an influenza outbreak, the postprophylaxis risk of influenza-like illness and hospitalisation among residents of long-term care facilities in Alberta (outcome variables) using multivariable linear and Poisson regression models.

RESULTS

Oseltamivir prophylaxis decision-making time was positively associated with the postintervention duration of an outbreak, with a 1-day delay in making decision on oseltamivir prophylaxis associated with 2.22 (95% CI 1.37 to 3.06) more days of the duration of an outbreak after controlling for potential confounding effect of the number of residents at risk at intervention, outbreak progression time, prevalence of influenza-like illness during outbreak progression, facility location, presence of mixed strain and based on optimal timing of oseltamivir prophylaxis. Although not statistically significant, a 1-day delay in making decision on oseltamivir prophylaxis was associated with a 5% (95% CI -1% to 11%) increase in the postintervention risk of influenza-like illness, and a 6% (95% CI -8% to 22%) increase in the postintervention risk of hospitalisation after controlling for the same potential confounders.

CONCLUSIONS

Our study demonstrated benefits of using oseltamivir prophylaxis to shorten the duration of influenza outbreaks; however, there were no significant differences in the influenza-like illness and hospitalisation risk occurring after the intervention. Surveillance data may offer means of rapid evaluation of oseltamivir prophylaxis in long-term care facilities as a public health measure.

Effect of antiviral prophylaxis on influenza outbreaks in aged care facilities in three local health districts in New South Wales, Australia, 2014

BACKGROUND

There was a record number (n = 111) of influenza outbreaks in aged care facilities in New South Wales, Australia during 2014. To determine the impact of antiviral prophylaxis recommendations in practice, influenza outbreak data were compared for facilities in which antiviral prophylaxis and treatment were recommended and for those in which antivirals were recommended for treatment only.

METHODS

Routinely collected outbreak data were extracted from the Notifiable Conditions Information Management System for two Local Health Districts where antiviral prophylaxis was routinely recommended and one Local Health District where antivirals were recommended for treatment but not routinely for prophylaxis. Data collected on residents included counts of influenza-like illness, confirmed influenza, hospitalizations and related deaths. Dates of onset, notification, influenza confirmation and antiviral recommendations were also collected for analysis. The Mann-Whitney U test was used to assess the significance of differences between group medians for key parameters.

RESULTS

A total of 41 outbreaks (12 in the prophylaxis group and 29 in the treatment-only group) were included in the analysis. There was no significant difference in overall outbreak duration; outbreak duration after notification; or attack, hospitalization or case fatality rates between the two groups. The prophylaxis group had significantly higher cases with influenza-like illness (P = 0.03) and cases recommended antiviral treatment per facility (P = 0.01).

DISCUSSION

This study found no significant difference in key outbreak parameters between the two groups. However, further high quality evidence is needed to guide the use of antivirals in responding to influenza outbreaks in aged care facilities.

The accuracy and timeliness of neuraminidase inhibitor dispensing data for predicting laboratory-confirmed influenza

Neuraminidase inhibitor (NI) dispensing has emerged as a possible automated data source for influenza surveillance. We aimed to evaluate its timeliness, correlation, and predictive accuracy in relation to influenza activity in Quebec, Canada, 2010–2013. Our secondary objective was to use the same metrics to compare NI dispensing to visits for influenza-like illness (ILI) in emergency departments (EDs). Provincial weekly counts of positive influenza laboratory tests were used as a reference measure for the level of influenza circulation. We applied ARIMA models to account for serial correlation. We computed cross-correlations to measure the strengths of association and lead-lag relationships between NI dispensing, ILI ED visits, and our reference indicator. Finally, using an ARIMA model, we evaluated the ability of NI dispensing and ILI ED visits to predict laboratory-confirmed influenza. NI dispensing was significantly correlated (R = 0·68) with influenza activity with no lag. The maximal correlation of ILI ED visits was not as strong (R = 0·50). Both NI dispensing and ILI ED visits were significant predictors of laboratory-confirmed influenza in a multivariable model; predictive potential was greatest when NI counts were lagged to precede laboratory surveillance by 2 weeks. We conclude that NI dispensing data provides timely and valuable information for influenza surveillance.

Interim estimates of 2014/15 influenza vaccine effectiveness in preventing laboratory-confirmed influenza-related hospitalisation from the Serious Outcomes Surveillance Network of the Canadian Immunization Research Network, January 2015

Binary file ES_Abstracts_Final_ECDC.txt matches

A prospective observational study of oseltamivir safety and tolerability in infants and young children ≤24 months

PURPOSE

Infants and young children are at elevated risk of influenza-associated complications, but information on the safety of antiviral therapies is limited in this age group.

METHODS

In this prospective open-label observational safety study, children aged ≤24 months with a clinical diagnosis of influenza in routine practice received either no antiviral treatment ('unexposed' group) or oseltamivir treatment or prophylaxis ('exposed' group), according to the physician's judgment. Patients were followed up for 30 days after the baseline visit.

RESULTS

Adverse events (AEs) were analysed in 1065 patients; they were reported in 390/711 (54.9%) in the unexposed group, 167/340 (49.1%) patients in the exposed group, and 6/14 prophylaxis patients. Cough and rhinitis were the most common events, reported more often in unexposed children (22.9 and 20.3% respectively) than in exposed children (13.2 and 10.0%; p < 0.001); pyrexia, diarrhoea and vomiting were less common, occurring at similar rates in exposed and unexposed patients. Nasal congestion (3.5%), bronchitis (5.6%) and upper respiratory tract infection (1.5%) were reported more frequently in exposed patients than in unexposed patients (0.7, 2.7 and 0.1% respectively; p < 0.05). In the exposed group, 11.2% of patients (n = 38) experienced 41 AEs considered at least possibly related to oseltamivir, none being assessed as serious. Overall, there were 79 serious AEs in 59 patients. Eleven discontinued treatment because of an AE.

CONCLUSIONS

Oseltamivir has a good tolerability profile in infants and children aged ≤24 months. These findings contributed to the recent FDA approval of oseltamivir for treating infants aged 2-51 weeks.

Risk management of seasonal influenza during pregnancy: current perspectives

Influenza poses unique risks to pregnant women, who are particularly susceptible to morbidity and mortality. Historically, pregnant women have been overrepresented among patients with severe illness and complications from influenza, and have been more likely to require hospitalization and intensive care unit admission. An increased risk of adverse outcomes is also present for fetuses/neonates born to women affected by influenza during pregnancy. These risks to mothers and babies have been observed during both nonpandemic and pandemic influenza seasons. During the H1N1 influenza pandemic of 2009-2010, pregnant women were more likely to be hospitalized or admitted to intensive care units, and were at higher risk of death compared to nonpregnant adults. Vaccination remains the most effective intervention to prevent severe illness, and antiviral medications are an important adjunct to ameliorate disease when it occurs. Unfortunately, despite national guidelines recommending universal vaccination for women who are pregnant during influenza season, actual vaccination rates do not achieve desired targets among pregnant women. Pregnant women are also sometimes reluctant to use antiviral medications during pregnancy. Some of the barriers to use of vaccines and medications during pregnancy are a lack of knowledge of recommendations and of safety data. By improving knowledge and understanding of influenza and vaccination recommendations, vaccine acceptance rates among pregnant women can be improved. Currently, the appropriate use of vaccination and antiviral medications is the best line of defense against influenza and its sequelae among pregnant women, and strategies to increase acceptance are crucial. This article will review the importance of influenza in pregnancy, and discuss vaccination and antiviral medications for pregnant women.

Trends in antiviral therapy of adults hospitalized with influenza in Canada since the end of the 2009 pandemic

Background

Multiple observational studies have associated antiviral treatment of patients hospitalized with influenza with improved outcome, including reduced mortality. During the 2009–2010 H1N1 pandemic increased use of antiviral treatment of hospital patients was reported. We have carried out prospective surveillance for influenza in patients in a large network of Canadian hospitals since 2006. We wished to assess trends in antiviral use in the two seasons (2010–2011 and 2011–2012) since the end of the pandemic.

Findings

Adults (>16 years) testing positive for influenza at the time of or during admission to participating Canadian hospitals were prospectively reviewed. In 2009–2010 there were 1132 confirmed cases, 1107 in 2010–2011 and 631 in 2011–2012. Information on antiviral therapy was available in >95% in each year. Rising to 89.6% in 2009, the proportion of adult patients treated with antiviral therapy fell to 79.9% and 65.7% in the two subsequent seasons (p < 0.001). Oseltamivir was the antiviral agent used in >98% of cases in each year. The median time from onset of symptoms to initiation of antiviral therapy was three days. The treatment proportion fell across all age groups, co-morbid conditions and disease severity.

Conclusion

Despite evidence for benefit of antiviral therapy, and clinical practice guidelines recommending treatment of this population, antiviral therapy of Canadian adults hospitalized with influenza has progressively fallen in the two seasons since the end of the 2009–2010 influenza pandemic.

Emergence of an oseltamivir-resistant influenza A/H3N2 virus in an elderly patient receiving a suboptimal dose of antiviral prophylaxis

We report the emergence of an influenza virus A/H3N2-E119V neuraminidase variant from an elderly patient with renal dysfunction who received a suboptimal dose of oseltamivir prophylaxis. In neuraminidase inhibition assays, the E119V variant showed a 413-fold increase in the 50% inhibitory oseltamivir concentration and grew at titers comparable to those of the wild type in vitro.

Can informal social distancing interventions minimize demand for antiviral treatment during a severe pandemic?

Background

In the case of a pandemic, individuals may alter their behaviour. A dynamic model incorporating social distancing can provide a mechanism to consider complex scenarios to support decisions regarding antiviral stockpile size while considering uncertainty around behavioural interventions. We have examined the impact of social distancing measures on the demand for limited healthcare resources such as antiviral drugs from a central stockpile during a severe pandemic.

Methods

We used an existing age-structured model for pandemic influenza in Canada and biologically plausible scenarios for severe influenza transmission within the population. We incorporated data from published reports regarding stated intentions to change behaviour during a pandemic as well as the magnitude and duration of time that individuals expected to maintain the behavioural change. We ran simulations for all combinations of parameter values to identify the projected antiviral requirements in each scenario.

Results

With 12 weeks of distancing, the effect is relatively small for the lowest R0 of 1.6 with a projected stockpile to treat 25.6% being required (IQR = 21.7 – 28.7%) unless the proportion of people involved (81%) and magnitude of the behaviour change is large (69% reduction in contacts). If 24 weeks of distancing occurs, with only a low to moderate reduction in contacts (38% or less), it is not possible to bring treatment requirements below 20% regardless of what proportion of the population engages in distancing measures when transmissibility is high (R0 = 2.0; stockpile size = 31%, IQR = 29.2 – 33.5%).

Conclusions

Our results demonstrate that the magnitude and duration of social distancing behaviours during a severe pandemic have an impact on the need for antiviral drugs. However, significant investments over a long period of time (>16 weeks) are required to decrease the need for antiviral treatment to below 10% of the total population for a highly transmissible viral strain (R0 > 1.8). Encouraging individuals to adopt behaviours that decrease their daily contact rate can help to control the spread of the virus until a vaccine becomes available however; relying on these measures to justify stockpiling fewer courses of treatment will not be sufficient in the case of a severe pandemic.

Minimizing infection risks after paediatric organ transplants: Advice for practitioners

Paediatric patients who have undergone an organ transplant face risks associated with different infectious diseases. Their susceptibility is increased by treatment with immunosuppressive medications. More of these patients are being cared for in community settings. This practice point provides guidance on key aspects in the prevention and treatment common infections.

The use of antiviral drugs for influenza: Guidance for practitioners 2012/2013

The present article addresses the use of antiviral drugs in the management of seasonal influenza illness for the 2012/2013 season. It updates the previous document published in 2011 (1). Noteworthy guidance updates since 2011 include the following: Seasonal influenza in 2012/2013 is predicted to be caused by two human influenza A and one influenza B strain, all of which are anticipated to remain generally susceptible to oseltamivir.The predicted strains are A/California/7/2009 (H1N1) pdm09-like, A/Victoria/361/2011 (H3N2)-like and B/Wisconsin/1/2010-like (Yamagata lineage). All are included in the seasonal influenza vaccine and are susceptible to oseltamivir.Swine-variant H3N2v, which has rarely caused infection in humans exposed to infected swine within the past year in the United States, is susceptible to oseltamivir. It is not included in the current seasonal influenza vaccine.It is still considered that initiation of antiviral therapy more than 36 h to 48 h after onset of symptoms is beneficial in patients hospitalized with complicated influenza and severe illness.Oseltamivir continues to be recommended for the treatment of influenza in pregnant women.The use of antiviral drugs among measures to control outbreaks of influenza in closed facilities such as correctional institutions is now included in the present document.