Use of neuraminidase inhibitors for rapid containment of influenza: a systematic review and meta-analysis of individual and household transmission studies

A noninferiority randomized open-label pilot study of 3- versus 7-day influenza postexposure prophylaxis with oseltamivir in hospitalized children

Short influenza postexposure prophylaxis (PEP) showed high efficacy in adults, but studies in children are lacking. This randomized open-label pilot trial aimed to verify noninferiority of a 3- versus 7-day prophylaxis with oral oseltamivir in hospitalized children. Influenza contacts were randomized to the 3- or 7-day group and efficacy, relative risk of adverse events (AEs), and the cumulative costs of drugs and AEs management were compared. The intention-to-treat (ITT) analysis included 59 children (n = 28 and n = 31 in the 3- and 7-day group, respectively). The efficacy was 100% (95% CI 87.7-100%) versus 93.6% (95% CI 78.6-99.2%) in the 3- and 7-day group; the differences were statistically insignificant. A per-protocol (PP) analysis including 56 patients (n = 27 and n = 29, respectively) showed 100% (95% CI 87.2-100%) and 93.1% (95% CI 77.2-99.2%) efficacy, respectively, without statistical significance. Differences were within the predefined noninferiority margin with an efficacy difference Δ = 6.45 percentage points (p.p.) with 1-sided 95% CI (- 2.8, - 1.31, p = 0.86; ITT) and Δ = 6.9 p.p. (1-sided 95% CI - 2.83, - 1.27, p = 0.85; PP). Adverse events did not differ significantly, while the cumulative costs of the prophylaxis and AEs management were higher in the 7-day group (median 10.5 euro vs. 4.5 euro, p < 0.01). This pilot study showed the noninferiority of the 3-day versus 7-day PEP, which was associated with lower costs.Trial registration number: NCT04297462, 5th March 2020, restrospectively registered.

Characteristics and determinants of seasonal influenza vaccination in Manitoba, Canada: A population-wide record-linkage study

Background

Seasonal influenza vaccine (SIV) uptake (receipt of vaccine) in Manitoba, Canada is consistently low notwithstanding vaccine availability and free-of-charge vaccination. Despite, there is a lack of published evidence on the determinants of uptake of the vaccine. We sought to assess the association between SIV uptake and certain population and primary care physician (PCP) characteristics in Manitoba.

Methods

We conducted a longitudinal study utilizing Manitoba administrative health databases. We summarized SIV uptake from 2000/01-2019/20 influenza seasons across subpopulations defined by socioeconomic, health-related and PCP characteristics. Utilizing multivariable generalized estimating equation logistic regression models, we assessed the association between SIV uptake and the socioeconomic, health-related and PCP characteristics, stratified by age group (<5-, 5-17-, 18-44-, 45-64-, ≥65-year-olds) and sex. Results are adjusted odds ratios with associated 95 % confidence intervals.

Results

SIV uptake percentage increased over time with 4.4 %, 13.1 %, 17.5 % and 21.7 % of < 5-year-olds, 2 %, 4.9 %, 9.7 % and 13.1 % of 5-17-year-olds, 5.4 %, 8.8 %, 10.7 % and 13.5 % of 18-44-year-olds, 16.8 %, 21.3 %, 23.6 % and 24.6 % of 45-64-year-olds receiving the SIV in 2000-2004, 2005-2009, 2010-2014 and 2015-2019, respectively. There was a decline among ≥ 65-year-olds from 58.5 % to 53.5 %. We observed a similar pattern across subpopulations. There were significantly increased odds of SIV uptake among females within the age groups ≥ 18 years, in higher income quintiles, mostly with increased contact with a PCP/hospitalization within age groups ≥ 18 years, among those who had older or female PCPs (the opposite observation among ≥ 65-year-olds) and whose PCP administered at least one SIV in prior influenza season. These observations were largely consistent irrespective of sex.

Conclusion

SIV uptake in Manitoba appears to increase with age, and many socioeconomic, health-related and PCP characteristics appear to be associated with it. These findings may inform targeted vaccination programs to optimize influenza vaccination in Manitoba and similar Canadian jurisdictions.

The Impact of Coronavirus Disease 2019 on Viral, Bacterial, and Fungal Respiratory Infections

Although coronavirus disease 2019 (COVID-19) remains an ongoing threat, concerns regarding other respiratory infections remain. Throughout the COVID-19 pandemic various epidemiologic trends have been observed in other respiratory viruses including a reduction in influenza and respiratory syncytial virus infections following onset of the COVID-19 pandemic. Observations suggest that infections with other respiratory viruses were reduced with social distancing, mask wearing, eye protection, and hand hygiene practices. Coinfections with COVID-19 exist not only with other respiratory viruses but also with bacterial pneumonias and other nosocomial and opportunistic infections. Coinfections have been associated with increased severity of illness and other adverse outcomes.

An overview of the characteristics and methodological standards across systematic reviews with Meta-analysis of efficacy/effectiveness of influenza antiviral drugs

BACKGROUND

Influenza antiviral drugs remain controversial and it is not clear if conclusions on their efficacy/effectiveness are based on high quality systematic reviews (SRs). We systematically identified, critically appraised, and summarized the characteristics and adherence to methodological standards in SRs with meta-analysis of efficacy/effectiveness of influenza antiviral drugs for prevention and/or treatment of influenza.

METHODS

We searched MEDLINE, Embase, Scopus, CINAHL, Global Health, and CDSR for English-language SR publications up to July 2020. We summarized the characteristics, adherence to methodological standards and SR quality (AMSTAR 2).

RESULTS

From a total 3,898 citations after removal of duplicates from all identified citations, we included 24 SRs. Seventy-five percent (n = 18) were of a critically low quality, 8% (n = 2) of a low quality, 17% (n = 4) of a moderate quality, and none were of a high quality. Seventeen percent (n = 4) were industry-funded, 4% (n = 1) coauthored by industry employee(s), and 33% (n = 8) commissioned by an organization or authority. Only 33% percent (n = 8) reported protocol registration, 4% (n = 1) reported collaboration with a knowledge synthesis librarian/information specialist, and 17% (n = 4) utilized a systematic review reporting checklist.

CONCLUSIONS

The evidence suggests that SRs of efficacy/effectiveness of influenza antiviral drugs are mostly of critically low quality and do not follow current best SR practices. These findings are significant in view of the important role of SRs in decision-making and the controversies that surround the use of the influenza antiviral drugs. However, the findings should not be interpreted to mean curtailment/cessation of use of antiviral drugs for influenza.

Effects of baloxavir and oseltamivir antiviral therapy on the transmission of seasonal influenza in China: A mathematical modeling analysis

New antiviral influenza treatments can effectively alleviate illness while reducing viral shedding. However, how such effects can translate into lower population infections of seasonal influenza in China remains unknown. To shed light on the public health impacts of novel antiviral agents for influenza, we constructed a dynamic transmission model to simulate the seasonal influenza epidemics in China. Two antivirus treatments, baloxavir and oseltamivir, were evaluated by estimating their impacts on the incidences of influenza infection in a single flu season. In the base-case analysis of a 10% antiviral treatment uptake rate, 2760 and 3420 per 10 000 persons contracted influenza under the treatment of baloxavir and oseltamivir, respectively. These incidence rates amounted to an 18.90% relative risk reduction (RRR) of infection associated with baloxavir in relation to oseltamivir. The corresponding RRR was 82.16% when the antiviral treatment uptake rate was increased to 35%. In addition, the peak of the prevalence of infected individuals per 10 000 persons under the baloxavir treatment was 177 (range: 93-274) fewer than that of oseltamivir. Our analyses suggest that the baloxavir treatment strategy reduces the incidence of influenza in China compared with oseltamivir in the setting of a seasonal flu epidemic. Also, increasing the uptake rate of antiviral treatment can potentially prevent millions of infections during a single flu season.

System dynamic modelling of healthcare associated influenza -a tool for infection control

BACKGROUND

The transmission dynamics of influenza virus within healthcare settings are not fully understood. Capturing the interplay between host, viral and environmental factors is difficult using conventional research methods. Instead, system dynamic modelling may be used to illustrate the complex scenarios including non-linear relationships and multiple interactions which occur within hospitals during a seasonal influenza epidemic. We developed such a model intended as a support for health-care providers in identifying potentially effective control strategies to prevent influenza transmission.

METHODS

By using computer simulation software, we constructed a system dynamic model to illustrate transmission dynamics within a large acute-care hospital. We used local real-world clinical and epidemiological data collected during the season 2016/17, as well as data from the national surveillance programs and relevant publications to form the basic structure of the model. Multiple stepwise simulations were performed to identify the relative effectiveness of various control strategies and to produce estimates of the accumulated number of healthcare-associated influenza cases per season.

RESULTS

Scenarios regarding the number of patients exposed for influenza virus by shared room and the extent of antiviral prophylaxis and treatment were investigated in relation to estimations of influenza vaccine coverage, vaccine effectiveness and inflow of patients with influenza. In total, 680 simulations were performed, of which each one resulted in an estimated number per season. The most effective preventive measure identified by our model was administration of antiviral prophylaxis to exposed patients followed by reducing the number of patients receiving care in shared rooms.

CONCLUSIONS

This study presents an system dynamic model that can be used to capture the complex dynamics of in-hospital transmission of viral infections and identify potentially effective interventions to prevent healthcare-associated influenza infections. Our simulations identified antiviral prophylaxis as the most effective way to control in-hospital influenza transmission.

Household clustering supports a novel chemoprophylaxis trial design for a mosquito-borne viral disease

Infections because of chikungunya and other mosquito-borne viruses, such as dengue and Zika, represent an area of significant unmet medical need. There are currently no approved medicines for prophylaxis or treatment of these diseases, and the development and implementation of vaccines against these viruses have proved problematic. Although antiviral molecules with treatment and prophylactic potential against the chikungunya virus have been identified, no successful field trials have been reported. Chemoprophylaxis may be attractive for unvaccinated at-risk populations; however, performing a successful chemoprophylaxis trial during a chikungunya outbreak will require a clearly identifiable at-risk population. We propose the application of a household transmission model as used in testing drugs against respiratory viruses. Current evidence on household clustering of chikungunya and other Aedes mosquito-borne viral infections is supportive. We suggest that this model may improve prophylaxis trial feasibility and focus research and future treatment on a population likely to benefit.

Comparison of intra-familial transmission of influenza virus from index patients treated with baloxavir marboxil or oseltamivir using an influenza transmission model and a health insurance claims database

Background

Influenza affects approximately a billion people globally, including > 10 million Japanese individuals every year. Baloxavir marboxil (baloxavir [BXM]; a selective cap-dependent endonuclease inhibitor) is approved for influenza treatment in Japan. We compared the incidence of intra-familial transmission of influenza between BXM and oseltamivir (OTV) treatments using a simulation model.

Methods

Using the JMDC Claims Database, we identified index case (IC) as the first family member diagnosed with influenza during the 2018–19 influenza season, and classified the families into BXM or OTV group per the drug dispensed to ICs. Using a novel influenza intra-familial infection model, we simulated the duration of influenza infection in ICs based on agent-specific virus shedding periods. Intra-familial infections were defined as non-IC family members infected during the agent-specific viral shedding period in ICs. The virus incubation periods in the non-IC family members were considered to exclude secondary infections from potentially external exposure. The primary endpoint was proportion of families with intra-familial infections. For between-group comparisons, we used a multivariate logistic regression model.

Results

The median proportion of families with intra-familial transmission was 9.57% and 19.35% in the BXM (N = 84 672) and OTV (N = 62 004) groups, respectively. The multivariate odds ratio of 1.73 (2.5th–97.5th percentiles, 1.68–1.77) indicated a substantially higher incidence of intra-familial infections in the OTV group versus the BXM group. Subgroup analyses by ICs’ age category, virus type, and month of onset revealed similar trends favoring BXM.

Conclusions

BXM treatment of ICs may contribute to a greater reduction in intra-familial influenza transmission than OTV treatment.

Influenza Management During the COVID-19 Pandemic: A Review of Recent Innovations in Antiviral Therapy and Relevance to Primary Care Practice

Seasonal influenza requires appropriate management to protect public health and resources. Decreasing the burden of influenza will depend primarily on increasing vaccination rates as well as prompt initiation of antiviral therapy within 48 hours of symptom onset, especially in the context of the current coronavirus disease 2019 pandemic. A careful approach is required to prevent health services from being overwhelmed by a surge in demand that could exceed capacity. This review highlights the societal burden of influenza and discusses the prevention, diagnosis, and treatment of influenza as a complicating addition to the challenges of the coronavirus disease 2019 pandemic. The importance of vaccination for seasonal influenza and the role of antiviral therapy in the treatment and prophylaxis of seasonal influenza, including the most up-to-date recommendations from the Centers for Disease Control and Prevention for influenza management, will also be reviewed.

Influenza

Seasonal influenza epidemics of variable severity pose challenges to public health. Annual vaccination is the primary way to prevent influenza, and a wide range of vaccines are available, including inactivated or live attenuated standard-dose, recombinant vaccines, as well as adjuvanted or high-dose vaccines for persons aged 65 years or older. Persons at increased risk for influenza complications include young children, persons with underlying medical conditions, and older adults. Prompt diagnosis of influenza can facilitate early initiation of antiviral treatment that provides the greatest clinical benefit. This article summarizes recommendations for providers on influenza vaccination, diagnostic testing, and antiviral treatment.

Reducing influenza virus transmission: the value of antiviral treatment

Prompt antiviral treatment has the potential to reduce influenza virus transmission to close contacts, but rigorous data on the magnitude of treatment effects on transmission are limited. Animal model data indicate that rapid reductions in viral replication after antiviral treatment reduce the risk of transmission. Observational and clinical trial data with oseltamivir and other neuraminidase inhibitors indicate that prompt treatment of household index patients seems to reduce the risk of illness in contacts, although the magnitude of the reported effects has varied widely across studies. In addition, the potential risk of transmitting drug-resistant variants exists with all approved classes of influenza antivirals. A controlled trial examining baloxavir treatment efficacy to reduce transmission, including the risk of transmitting virus with reduced baloxavir susceptibility, is currently in progress. If reduced transmission risk is confirmed, modeling studies indicate that early treatment could have major epidemiologic benefits in seasonal and pandemic influenza.

Sex Differences in Respiratory Viral Pathogenesis and Treatments

Biological sex affects the outcome of diverse respiratory viral infections. The pathogenesis of respiratory infections caused by viruses ranging from respiratory syncytial virus to influenza viruses and severe acute respiratory syndrome coronavirus 2 differs between the sexes across the life course. Generally, males are more susceptible to severe outcomes from respiratory viral infections at younger and older ages. During reproductive years (i.e., after puberty and prior to menopause), females are often at greater risk than males for severe outcomes. Pregnancy and biological sex affect the pathogenesis of respiratory viral infections. In addition to sex differences in the pathogenesis of disease, there are consistent sex differences in responses to treatments, with females often developing greater immune responses but experiencing more adverse reactions than males. Animal models provide mechanistic insights into the causes of sex differences in respiratory virus pathogenesis and treatment outcomes, where available. Expected final online publication date for the Annual Review of Virology, Volume 8 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Divergent Mast Cell Responses Modulate Antiviral Immunity During Influenza Virus Infection

Influenza A virus (IAV) is a respiratory pathogen that infects millions of people each year. Both seasonal and pandemic strains of IAV are capable of causing severe respiratory disease with a high risk of respiratory failure and opportunistic secondary infection. A strong inflammatory cytokine response is a hallmark of severe IAV infection. The widespread tissue damage and edema in the lung during severe influenza is largely attributed to an overexuberant production of inflammatory cytokines and cell killing by resident and infiltrating leukocytes. Mast cells (MCs) are a sentinel hematopoietic cell type situated at mucosal sites, including the lung. Poised to react immediately upon detecting infection, MCs produce a vast array of immune modulating molecules, including inflammatory cytokines, chemokines, and proteases. As such, MCs have been implicated as a source of the immunopathology observed in severe influenza. However, a growing body of evidence indicates that MCs play an essential role not only in inducing an inflammatory response but in suppressing inflammation as well. MC-derived immune suppressive cytokines are essential to the resolution of a number of viral infections and other immune insults. Absence of MCs prolongs infection, exacerbates tissue damage, and contributes to dissemination of the pathogen to other tissues. Production of cytokines such as IL-10 and IL-6 by MCs is essential for mitigating the inflammation and tissue damage caused by innate and adaptive immune cells alike. The two opposing functions of MCs—one pro-inflammatory and one anti-inflammatory—distinguish MCs as master regulators of immunity at the site of infection. Amongst the first cells to respond to infection or injury, MCs persist for the duration of the infection, modulating the recruitment, activation, and eventual suppression of other immune cells. In this review, we will discuss the immune modulatory roles of MCs over the course of viral infection and propose that the immune suppressive mediators produced by MCs are vital to minimizing immunopathology during influenza infection.

A retrospective observational study of the treatment of a nosocomial infection caused by oseltamivir-resistant influenza virus A with baloxavir marboxil

BACKGROUND

Nosocomial (hospital-acquired) influenza A virus infection is a very important clinical issue. The objective of this study is to describe the effect of baloxavir marboxil in controlling an outbreak of this infection.

METHODS

A retrospective observational study was performed to assess the effectiveness of baloxavir marboxil in the treatment of nosocomial infections caused by oseltamivir-resistant influenza virus A.

RESULTS

In September 2019, there was an outbreak of nosocomial influenza A(H1N1)pdm09 viral infection in one out of three facility wards for inpatients at the Okinawa Nanbu Regional Center for Children with Special Needs. Symptomatic staff members were kept off duty until they remained afebrile for 2 days. Prophylactic oseltamivir was administered to inpatients (n = 37) and to staff members (n = 16) who voluntarily requested the drug. However, both inpatients and staff members showed influenza A infection during prophylactic use of oseltamivir. The A(H1N1)pdm09 virus sample obtained from one patient was shown to be oseltamivir-resistant. After administration of baloxavir marboxil, the nosocomial outbreak gradually ceased. Moreover, the time (hours) to alleviation of fever in the oseltamivir group (n = 11) and baloxavir marboxil group (n = 13) was significantly different (p = 0.0034).

CONCLUSION

Our report provides evidence for the usefulness of baloxavir marboxil in treating influenza A patients who have received prophylactic doses of oseltamivir. This is the first report describing the successful use of baloxavir marboxil for of a nosocomial outbreak caused by oseltamivir-resistant influenza A virus.

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

Background

The efficacy and optimal duration of postexposure influenza prophylaxis with oseltamivir are undetermined in hospital settings, where immediate separation from index cases is not feasible.

Methods

In 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.

Results

Among 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).

Conclusions

For 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.

ClinicalTrialsgov Registration

NCT03899571.

Incidence and characteristics of nosocomial influenza in a country with low vaccine coverage

BACKGROUND

Influenza vaccination coverage is low in France, in at-risk patients and in healthcare workers.

AIM

We aimed to estimate the incidence of nosocomial influenza, its characteristics and outcome.

METHODS

During one influenza season, we retrospectively evaluated all cases of documented influenza. Inpatients with symptoms onset ≥48 h after admission were enrolled. Data were collected on a standardized questionnaire.

RESULTS

From November 2017 to April 2018, 860 patients tested positive for influenza by polymerase chain reaction analysis on a respiratory sample. Among them, 204 (23.7%) were diagnosed ≥48 h after admission, of whom 57 (6.6% of all influenza cases) fulfilled inclusion criteria for nosocomial influenza: 26 women and 31 men, median age 82 years (interquartile range, 72.2-86.9). Twenty patients (38.6%) had recently (<6 months) received the seasonal influenza vaccine. Median time between admission and symptoms onset, and between symptoms onset and diagnosis were, respectively, 11 days (7-19.5) and 29 h (15.5-48). Influenza was mostly acquired in a double-bedded room (N = 39, 68.4%), with documented exposure in 14 cases. Influenza B virus was more common in nosocomial (46/57, 80.7%), than in community-acquired cases (359/803, 44.6%), P<0.001. Mortality rate at three months was 15.8% (N = 9). Incidence of nosocomial influenza was estimated at 0.22 per 1000 hospital-days during the study period.

CONCLUSION

Nosocomial influenza is not rare in elderly inpatients, and may have severe consequences. Influenza B virus was over-represented, which suggests higher transmissibility and/or transmission clusters.

COVID-19: Time for Post-Exposure Prophylaxis?

From a healthcare perspective, infection due to the novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) and the ensuing syndrome called COVID-19 (coronavirus disease 2019) represents the biggest challenge the world has faced in several decades. Particularly worrisome are the high contagiousness of the virus and the saturation of hospitals' capacity due to overwhelming caseloads. Non-pharmaceutical interventions such as quarantine and inter-personal distancing are crucial to limiting the spread of the virus in the general population, but more tailored interventions may be needed at an individual level on a case-by-case basis. In this perspective, the most insidious situation is when an individual has contact with a contagious subject without adequate protection. If rapidly recognized afterwards, this occurrence may be promptly addressed through a post-exposure chemoprophylaxis (PEP) with antiviral drugs. This strategy has been implemented for other respiratory viruses (influenza above all) and was successfully used in South Korea among healthcare workers against the Middle East respiratory syndrome (MERS) coronavirus, by providing people who were exposed to high-risk contacts with lopinavir-ritonavir plus ribavirin. Initial experiences with the use of hydroxychloroquine to prevent COVID-19 also seem promising. Post-exposure chemoprophylaxis might help mitigate the spread of SARS-CoV-2 in the current phase of the COVID-19 pandemic.

Academic Life in Emergency Medicine (ALiEM) Blog and Podcast Watch: Infectious Diseases

The Academic Life in Emergency Medicine (ALiEM) Approved Instructional Resources (AIR) Series and Approved Instructional Resources - Professional (AIR-Pro) Series were created in 2014 and 2015, respectively, in response to the growing need to curate online educational content as well as create a nationally available curriculum that meets individualized interactive instruction criteria for emergency medicine (EM) trainees. These two online series identify high-quality educational blog and podcast content using an expert-based approach.

The AIR series is a continuously building curriculum originally based on the Council of Emergency Medicine Directors (CORD) testing schedule. In September 2019, 61 blog posts and podcasts published within the previous 12 months and relevant to infectious diseases were evaluated by eight attending physicians using the ALiEM AIR scoring instrument. In this review, we summarize the accredited posts on infectious diseases meeting our a priori quality criteria per evaluation by the reviewers.

Antivirals targeting the polymerase complex of influenza viruses

Current influenza antivirals have limitations with regard to their effectiveness and the potential emergence of resistance. Encouragingly, several new compounds which inhibit the polymerase of influenza viruses have recently been shown to have enhanced pre-clinical and clinical effectiveness compared to the neuraminidase inhibitors, the mainstay of influenza antiviral therapy over the last two decades. In this review we focus on four compounds which inhibit polymerase function, baloxavir marboxil, favipiravir, pimodivir and AL-794 and discuss their clinical and virological effectiveness, their propensity to select for resistance and their potential for future combination therapy with the most commonly used neuraminidase inhibitor, oseltamivir.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

The effect of neuraminidase inhibitors on household transmission in Japanese patients with influenza A and B infection: A prospective, observational study

Background

The relative ability of neuraminidase inhibitors (NAIs) to reduce household influenza transmission when given to index patients is not established.

Objectives

To compare daily secondary infection rates (SIR) of influenza A (A/H1pdm and A/H3) and B in households of index patients treated with oseltamivir, zanamivir, laninamivir, or peramivir.

Patients/Methods

This Japanese, single‐center, prospective, observational study (UMIN‐CTR: UMIN000024650) enrolled index patients with confirmed influenza who were treated with an NAI during 6 influenza seasons (2010‐2016). Secondary infection patients were household members diagnosed with the same influenza subtype 1‐7 days after onset in the index patient. Daily SIR was calculated using a modified Reed‐Frost model. The rate of household members with secondary infection and proportion of households with any secondary infection were also calculated.

Results

Index patients with influenza A (n = 1146) or B (n = 661) were enrolled (~3400 total index and secondary patients). Daily SIR for all virus subtypes was highest when oseltamivir was used (eg, unadjusted estimate: type A, 1.47% vs 0.71%‐1.13%; type B, 1.30% vs 0.59%‐0.88%). Pairwise comparisons revealed significant differences in daily SIR between NAIs for influenza type A, type B, and subtype A/H3; for example, for type A, SIR was significantly higher with oseltamivir than with peramivir or zanamivir. The rate of household members with secondary infection and proportion of households with any secondary infection also varied between NAIs.

Conclusions

Neuraminidase inhibitors differed in their ability to reduce household influenza transmission; transmission was highest with oseltamivir. Physicians may consider effects on household transmission when deciding which NAI to prescribe.

Treating Influenza Infection, From Now and Into the Future

Influenza viruses (IVs) are a continual threat to global health. The high mutation rate of the IV genome makes this virus incredibly successful, genetic drift allows for annual epidemics which result in thousands of deaths and millions of hospitalizations. Moreover, the emergence of new strains through genetic shift (e.g., swine-origin influenza A) can cause devastating global outbreaks of infection. Neuraminidase inhibitors (NAIs) are currently used to treat IV infection and act directly on viral proteins to halt IV spread. However, effectivity is limited late in infection and drug resistance can develop. New therapies which target highly conserved features of IV such as antibodies to the stem region of hemagglutinin or the IV RNA polymerase inhibitor: Favipiravir are currently in clinical trials. Compared to NAIs, these treatments have a higher tolerance for resistance and a longer therapeutic window and therefore, may prove more effective. However, clinical and experimental evidence has demonstrated that it is not just viral spread, but also the host inflammatory response and damage to the lung epithelium which dictate the outcome of IV infection. Therapeutic regimens for IV infection should therefore also regulate the host inflammatory response and protect epithelial cells from unnecessary cell death. Anti-inflammatory drugs such as etanercept, statins or cyclooxygenase enzyme 2 inhibitors may temper IV induced inflammation, demonstrating the possibility of repurposing these drugs as single or adjunct therapies for IV infection. IV binds to sialic acid receptors on the host cell surface to initiate infection and productive IV replication is primarily restricted to airway epithelial cells. Accordingly, targeting therapies to the epithelium will directly inhibit IV spread while minimizing off target consequences, such as over activation of immune cells. The neuraminidase mimic Fludase cleaves sialic acid receptors from the epithelium to inhibit IV entry to cells. While type III interferons activate an antiviral gene program in epithelial cells with minimal perturbation to the IV specific immune response. This review discusses the above-mentioned candidate anti-IV therapeutics and others at the preclinical and clinical trial stage.

Improving preparedness for the next flu pandemic

Pandemic influenza remains the single greatest threat to global heath security. Efforts to increase our preparedness, by improving predictions of viral emergence, spread and disease severity, by targeting reduced transmission and improved vaccination and by mitigating health impacts in low- and middle-income countries, should receive renewed urgency.

Antivirals for influenza-Like Illness? A randomised Controlled trial of Clinical and Cost effectiveness in primary CarE (ALIC4 E): the ALIC4 E protocol

INTRODUCTION

Effective management of seasonal and pandemic influenza is a high priority internationally. Guidelines in many countries recommend antiviral treatment for older people and individuals with comorbidity at increased risk of complications. However, antivirals are not often prescribed in primary care in Europe, partly because its clinical and cost effectiveness has been insufficiently demonstrated by non-industry funded and pragmatic studies.

METHODS AND ANALYSIS

Antivirals for influenza-Like Illness? An rCt of Clinical and Cost effectiveness in primary CarE is a European multinational, multicentre, open-labelled, non-industry funded, pragmatic, adaptive-platform, randomised controlled trial. Initial trial arms will be best usual primary care and best usual primary care plus treatment with oseltamivir for 5 days. We aim to recruit at least 2500 participants ≥1 year presenting with influenza-like illness (ILI), with symptom duration ≤72 hours in primary care over three consecutive periods of confirmed high influenza incidence. Participant outcomes will be followed up to 28 days by diary and telephone. The primary objective is to determine whether adding antiviral treatment to best usual primary care is effective in reducing time to return to usual daily activity with fever, headache and muscle ache reduced to minor severity or less. Secondary objectives include estimating cost-effectiveness, benefits in subgroups according to age (<12, 12-64 and >64 years), severity of symptoms at presentation (low, medium and high), comorbidity (yes/no), duration of symptoms (≤48 hours/>48-72 hours), complications (hospital admission and pneumonia), use of additional prescribed medication including antibiotics, use of over-the-counter medicines and self-management of ILI symptoms.

ETHICS AND DISSEMINATION

Research ethics committee (REC) approval was granted by the NRES Committee South Central (Oxford B) and Clinical Trial Authority (CTA) approval by The Medicines and Healthcare products Regulatory Agency. All participating countries gained national REC and CTA approval as required. Dissemination of results will be through peer-reviewed scientific journals and conference presentations.

TRIAL REGISTRATION NUMBER

ISRCTN27908921; Pre-results.

Safety and effectiveness of neuraminidase inhibitors for influenza treatment, prophylaxis, and outbreak control: a systematic review of systematic reviews and/or meta-analyses

Objectives

To review evidence from systematic reviews and/or meta-analyses (SR/MAs) regarding neuraminidase inhibitor (NI) safety and effectiveness.

Methods

We conducted an SR of SR/MAs of randomized control and/or observational studies. We searched eight electronic databases for SR/MAs that examined the effectiveness or safety of NIs administered for influenza (i.e. influenza-like illness or lab-confirmed) treatment or prophylaxis.

Results

We identified 27 (0.7%) eligible SR/MAs of 3723 articles reviewed. NI (n = 2) or oseltamivir (n = 1) versus no treatment were consistently associated with a decrease in mortality odds among the hospitalized, general population (OR range 0.2 - 0.8). Oseltamivir versus no treatment was associated with a decrease in hospitalization and pneumonia risk/odds in 2/4 SR/MAs. Oseltamivir (n = 4) and zanamivir (n = 3) were consistently associated with a 0.5 - 1 day decrease in symptom duration. Oseltamivir (n = 4) or zanamivir (n = 4) versus no prophylaxis were consistently associated with a decrease in the odds/risk of symptomatic secondary transmission (OR/RR range 0.1 - 0.5). Oseltamivir versus no treatment was consistently associated with a 1.5- to 2.5-fold increase in the odds/risk of nausea (n = 4) and vomiting (n = 5).

Conclusions

NI treatment is likely to be effective at reducing mortality among hospitalized patients, and symptom duration by up to 1 day in the general population. Oseltamivir or zanamivir prophylaxis are likely to be effective at reducing secondary symptomatic influenza transmission. Increased nausea and vomiting are likely associated with oseltamivir use. We recommend that decisions regarding NI use are made in consideration of potential adverse events, particularly for the general population at low risk of complications. Among hospitalized patients, NI administration seems warranted to reduce mortality risk.

Antiviral treatment of childhood influenza: an update

PURPOSE OF REVIEW

Influenza virus can cause severe or life-threatening infection in children. This review provides an update on antiviral medications available to treat and prevent influenza in both healthy children and children with underlying medical conditions, and recommendations on their appropriate use in the outpatient and inpatient settings.

RECENT FINDINGS

Despite the significant morbidity and mortality associated with influenza infection, a large number of children hospitalized with influenza do not receive specific antiviral treatment with a neuraminidase inhibitor. Although the effectiveness of this intervention has been debated, several recent observational studies have shown the potential benefits conferred by early antiviral treatment. Oral oseltamivir and inhaled zanamivir remain the best studied antiviral agents for influenza treatment and prevention. In addition, the US Food and Drug Administration recently approved peramivir, a novel neuraminidase inhibitor available for intravenous administration.

SUMMARY

Children with suspected or documented influenza infection benefit from early antiviral treatment with neuraminidase inhibitors that can shorten illness duration, decrease symptom severity, and lower the risk of complications leading to hospitalization and death. Unless contraindicated, all hospitalized children, children with underlying medical conditions, and those with severe or progressive symptoms of influenza should receive specific antiviral treatment for influenza with a neuraminidase inhibitor. Additionally, antiviral treatment of influenza-infected children in the outpatient setting should be strongly considered.

A meta-analysis of laninamivir octanoate for treatment and prophylaxis of influenza

BACKGROUND

Laninamivir octanoate is a recently developed inhaled neuraminidase inhibitor for treating influenza virus infection. We performed meta-analyses to clarify the efficacy of laninamivir octanoate on influenza treatment and prevention.

METHODS

MEDLINE and CENTRAL were searched to identify eligible studies. The log median time to event ratios (logMRs) and log odds ratios (logORs) were combined with meta-analysis.

RESULTS

Nine studies in treatment settings and three studies in prophylaxis settings were eligible for this meta-analysis. There was no significant difference between laninamivir octanoate and oseltamivir (8 studies, logMR 0.04, 95% CI [-0.05, 0.14]; P=0.36) or zanamivir (4 studies, logMR -0.01, 95% CI [-0.12, 0.11]; P=0.93) in alleviating fever. However, laninamivir octanoate was associated with significantly longer fever duration in treating H3N2 influenza as compared to oseltamivir (4 studies, logMR 0.29, 95% CI [0.00, 0.59]; P=0.047). Laninamivir octanoate was associated with significantly longer duration of fever as compared to peramivir (4 studies, logMR 0.46, 95% CI [0.14, 0.77]; P=0.004). Laninamivir octanoate significantly reduced the incidence of clinical influenza in post-exposure settings (3 studies, logOR -1.17, 95% CI [-1.72, -0.62]; P<0.001).

CONCLUSIONS

Overall, the efficacy of laninamivir octanoate in treating influenza was comparable to that of oseltamivir or zanamivir, but it should be noted that laninamivir octanoate was associated with significantly longer fever duration in treating influenza H3N2 as compared to oseltamivir and oseltamivir-resistant mutations in seasonal influenza H1N1 might have affected the results. Peramivir may be superior to laninamivir in treating influenza. Laninamivir octanoate is effective in preventing influenza in post-exposure settings as compared to placebo.

Influenza

Influenza is an infectious respiratory disease that, in humans, is caused by influenza A and influenza B viruses. Typically characterized by annual seasonal epidemics, sporadic pandemic outbreaks involve influenza A virus strains of zoonotic origin. The WHO estimates that annual epidemics of influenza result in ~1 billion infections, 3–5 million cases of severe illness and 300,000–500,000 deaths. The severity of pandemic influenza depends on multiple factors, including the virulence of the pandemic virus strain and the level of pre-existing immunity. The most severe influenza pandemic, in 1918, resulted in >40 million deaths worldwide. Influenza vaccines are formulated every year to match the circulating strains, as they evolve antigenically owing to antigenic drift. Nevertheless, vaccine efficacy is not optimal and is dramatically low in the case of an antigenic mismatch between the vaccine and the circulating virus strain. Antiviral agents that target the influenza virus enzyme neuraminidase have been developed for prophylaxis and therapy. However, the use of these antivirals is still limited. Emerging approaches to combat influenza include the development of universal influenza virus vaccines that provide protection against antigenically distant influenza viruses, but these vaccines need to be tested in clinical trials to ascertain their effectiveness.

The Effectiveness of Trivalent Inactivated Influenza Vaccine in Children with Acute Leukemia

OBJECTIVE

The objective of this study was to determine the effectiveness of trivalent inactivated influenza vaccine (TIV) for the prevention of laboratory-confirmed influenza and influenza-like illnesses (ILI) among children and adolescents receiving therapy for acute leukemia.

STUDY DESIGN

A retrospective review of the demographic and clinical characteristics of 498 patients at a pediatric cancer center who received therapy for acute leukemia during 3 successive influenza seasons (2010-2011 through 2012-2013).

RESULTS

In 498 patient seasons with a known immunization history (median age, 6 years; range, 1-21), 354 patients (71.1%) were immunized with TIV and 98 (19.7%) received a booster dose of vaccine. Vaccinated and unvaccinated patients had generally similar demographic characteristics. There were no differences in the overall rates of influenza or ILI between vaccinated and unvaccinated patients overall, or in any individual season. There was no difference in the rates of influenza or ILI between patients who received 1 dose of vaccine and those who received 2 doses. Time to first influenza infection and time to first ILI in vaccinated and unvaccinated patients were not different.

CONCLUSION

TIV did not protect children and adolescents with acute leukemia against laboratory-confirmed influenza or ILI. Future prospective studies should assess TIV effectiveness in high-risk subpopulations and alternative strategies to prevent influenza should be considered in this population.

Influenza

Influenza is an acute viral respiratory disease that affects persons of all ages and is associated with millions of medical visits, hundreds of thousands of hospitalizations, and thousands of deaths during annual winter epidemics of variable severity in the United States. Elderly persons have the highest influenza-associated hospitalization and mortality rates. The primary method of prevention is annual vaccination. Early antiviral treatment has the greatest clinical benefit; otherwise, management includes adherence to recommended infection prevention and control measures as well as supportive care of complications.

Influenza in long-term care facilities

Long-term care facility environments and the vulnerability of their residents provide a setting conducive to the rapid spread of influenza virus and other respiratory pathogens. Infections may be introduced by staff, visitors or new or transferred residents, and outbreaks of influenza in such settings can have devastating consequences for individuals, as well as placing extra strain on health services. As the population ages over the coming decades, increased provision of such facilities seems likely. The need for robust infection prevention and control practices will therefore remain of paramount importance if the impact of outbreaks is to be minimised. In this review, we discuss the nature of the problem of influenza in long-term care facilities, and approaches to preventive and control measures, including vaccination of residents and staff, and the use of antiviral drugs for treatment and prophylaxis, based on currently available evidence.

Influenza

Influenza is an acute respiratory illness, caused by influenza A, B, and C viruses, that occurs in local outbreaks or seasonal epidemics. Clinical illness follows a short incubation period and presentation ranges from asymptomatic to fulminant, depending on the characteristics of both the virus and the individual host. Influenza A viruses can also cause sporadic infections or spread worldwide in a pandemic when novel strains emerge in the human population from an animal host. New approaches to influenza prevention and treatment for management of both seasonal influenza epidemics and pandemics are desirable. In this Seminar, we discuss the clinical presentation, transmission, diagnosis, management, and prevention of seasonal influenza infection. We also review the animal-human interface of influenza, with a focus on current pandemic threats.

Inhalation of α-gal/sialic acid liposomes: a novel approach for inhibition of influenza virus infection?

Effective inhibition of influenza virus infection in symptomatic patients may be feasible by inhalation of aerosol-containing liposomes presenting α-gal epitopes and sialic acid epitopes. The virus binds to sialic acid epitopes and the natural anti-Gal antibody binds to α-gal epitopes on the liposomes and activates the complement system to generate chemotactic peptides that recruit macrophages. These macrophages bind and internalize via their Fc receptors, anti-Gal-coated liposomes and the influenza virus bound to them, process the viral antigens and transport them to the regional lymph nodes for eliciting a rapid, protective immune response that prevents progression of the virus infection.

Respiratory Infections in the U.S. Military: Recent Experience and Control

This comprehensive review outlines the impact of military-relevant respiratory infections, with special attention to recruit training environments, influenza pandemics in 1918 to 1919 and 2009 to 2010, and peacetime operations and conflicts in the past 25 years. Outbreaks and epidemiologic investigations of viral and bacterial infections among high-risk groups are presented, including (i) experience by recruits at training centers, (ii) impact on advanced trainees in special settings, (iii) morbidity sustained by shipboard personnel at sea, and (iv) experience of deployed personnel. Utilizing a pathogen-by-pathogen approach, we examine (i) epidemiology, (ii) impact in terms of morbidity and operational readiness, (iii) clinical presentation and outbreak potential, (iv) diagnostic modalities, (v) treatment approaches, and (vi) vaccine and other control measures. We also outline military-specific initiatives in (i) surveillance, (ii) vaccine development and policy, (iii) novel influenza and coronavirus diagnostic test development and surveillance methods, (iv) influenza virus transmission and severity prediction modeling efforts, and (v) evaluation and implementation of nonvaccine, nonpharmacologic interventions.