Search

Background The pharmacokinetics of oral favipiravir and the relationships of plasma concentrations to antiviral effects are incompletely studied in influenza. Methods Serial plasma samples were collected from adults with uncomplicated influenza who were randomized to favipiravir (1800 mg twice a day on day 1, 800 mg twice a day on days 2 to 5; n = 827) or placebo (n = 419) in 2 phase 3 trials. Post hoc analyses assessed the frequency of reaching an average minimum concentration (Cmin) ≥20 µg/mL, its association with antiviral efficacy, and factors associated with reduced favipiravir exposure. Results Wide interindividual variability existed in favipiravir concentrations, and this regimen failed to reach an average Cmin > 20 µg/mL in 41%–43% of participants. Those attaining this threshold showed greater reductions in nasopharyngeal infectious virus titers on treatment days 2 and 3 and lower viral titer area under the curve compared to those who did not. Those with average Cmin <20 µg/mL had over 2-fold higher mean ratios of the metabolite T-705M1 to favipiravir, consistent with greater metabolism, and were more likely to weigh > 80 kg (61.5%–64%). Conclusions Higher favipiravir levels with average Cmin > 20 µg/mL were associated with larger antiviral effects and more rapid illness alleviation compared to placebo and to favipiravir recipients with lower average Cmin values in uncomplicated influenza. Clinical Trials Registration. NCT1068912 and NCT01728753. [ABSTRACT FROM AUTHOR]

Background: The transmission of influenza virus in households, especially by children, is a major route of infection. Prior studies suggest that timely antiviral treatment of ill cases may reduce infection in household contacts. The aim of the study was to compare the effects of oseltamivir (OTV) and baloxavir marboxil (BXM) treatment of index cases on the secondary attack rate (SAR) of influenza within household. Methods: A post hoc analysis was done in BLOCKSTONE trial—a placebo‐controlled, double‐blinded post‐exposure prophylaxis of BXM. Data were derived from the laboratory‐confirmed index cases' household contacts who received placebo in the trial and also from household members who did not participate in the trial but completed illness questionnaires. To assess the SAR of household members, multivariate analyses adjusted for factors including age, vaccination status, and household size were performed and compared between contacts of index cases treated with BXM or OTV. Results: In total, 185 index cases (116 treated with BXM and 69 treated with OTV) and 410 household contacts (201 from trial, 209 by questionnaire) were included. The Poisson regression modeling showed that the SAR in household contacts of index cases treated with BXM and OTV was 10.8% and 18.5%, respectively; the adjusted relative reduction in SAR was 41.8% (95% confidence interval: 1.0%–65.7%, p = 0.0456) greater with BXM than OTV. Similar reductions were found in contacts from the trial and those included by questionnaire. Conclusion: BXM treatment of index cases appeared to result in a greater reduction in secondary household transmission than OTV treatment. [ABSTRACT FROM AUTHOR]

Background: We conducted double-blind, placebo-controlled trials assessing the efficacy and tolerability of favipiravir in acute influenza.Methods: Otherwise healthy adults with influenza-like symptoms and fever of ≤48 hours were randomized to favipiravir (1800 mg twice daily [BID] on day 1, 800 mg BID on days 2-5) or placebo tablets (1:1 in US316; 3:1 in US317). The primary efficacy endpoint was the time to illness alleviation when 6 influenza symptoms were self-rated as absent or mild and fever was absent in the intention-to-treat, influenza-infected participants.Results: In US316 (301 favipiravir, 322 placebo), favipiravir was associated with a 14.4-hour reduction (median, 84.2 vs 98.6 hours; P = .004) in time to illness alleviation vs placebo. In US317 (526 favipiravir, 169 placebo), favipiravir did not significantly reduce time to alleviation (median, 77.8 vs 83.9 hours). In both trials favipiravir was associated with reduced viral titers, RNA load area under the curve over days 1-5, and median times to cessation of virus detection (P < .001). Aside from asymptomatic hyperuricemia, no important differences in adverse events were found.Conclusions: This favipiravir dosing regimen demonstrated significant antiviral efficacy but inconsistent illness alleviation in uncomplicated influenza. Studies of higher doses and antiviral combinations for treating serious influenza and other RNA viral infections are warranted. Clinical Trials Registration. NCT02026349; NCT02008344. [ABSTRACT FROM AUTHOR]

Animal and human data indicate variable effects of interferons in treating coronavirus infections according to inflammatory status and timing of therapy. In this sub-study of the MIRACLE trial (MERS-CoV Infection Treated with a Combination of Lopinavir–Ritonavir and Interferon β-1b), we evaluated the heterogeneity of treatment effect of interferon-β1b and lopinavir–ritonavir versus placebo among hospitalized patients with MERS on 90-day mortality, according to cytokine levels and timing of therapy. We measured plasma levels of 17 cytokines at enrollment and tested the treatment effect on 90-day mortality according to cytokine levels (higher versus lower levels using the upper tertile (67%) as a cutoff point) and time to treatment (≤ 7 days versus > 7 days of symptom onset) using interaction tests. Among 70 included patients, 32 received interferon-β1b and lopinavir–ritonavir and 38 received placebo. Interferon-β1b and lopinavir–ritonavir reduced mortality in patients with lower IL-2, IL-8 and IL-13 plasma concentrations but not in patients with higher levels (p-value for interaction = 0.09, 0.07, and 0.05, respectively) and with early but not late therapy (p = 0.002). There was no statistically significant heterogeneity of treatment effect according to other cytokine levels. Further work is needed to evaluate whether the assessment of inflammatory status can help in identifying patients with MERS who may benefit from interferon-β1b and lopinavir–ritonavir. Trial registration: This is a sub-study of the MIRACLE trial (ClinicalTrials.gov number, NCT02845843). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The NIH Virtual SARS-CoV-2 Antiviral Summit, held on 6 November 2020, was organized to provide an overview on the status and challenges in developing antiviral therapeutics for coronavirus disease 2019 (COVID-19), including combinations of antivirals. Scientific experts from the public and private sectors convened virtually during a live videocast to discuss severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) targets for drug discovery as well as the preclinical tools needed to develop and evaluate effective small-molecule antivirals. The goals of the Summit were to review the current state of the science, identify unmet research needs, share insights and lessons learned from treating other infectious diseases, identify opportunities for public-private partnerships, and assist the research community in designing and developing antiviral therapeutics. This report includes an overview of therapeutic approaches, individual panel summaries, and a summary of the discussions and perspectives on the challenges ahead for antiviral development. [ABSTRACT FROM AUTHOR]

Background Baloxavir marboxil has demonstrated safety and efficacy in treating adult and adolescent outpatients with acute influenza (CAPSTONE-1 trial). Here, we report a subgroup analysis of outcomes in adolescents from the trial. Methods CAPSTONE-1 was a randomized, double-blind, placebo-controlled study. Eligible adolescent outpatients (aged 12-17 years of age) were randomized in a ratio of 2:1 to a single dose of baloxavir 40/80 mg if less than/greater than or equal to 80 kg or placebo. The main outcomes were the time to alleviation of symptoms (TTAS), duration of infectious virus detection, and incidence of adverse events (AEs). Results Among 117 adolescent patients, 90 (77%) comprised the intent-to-treat infected population (63 baloxavir and 27 placebo; 88.9% A(H3N2)). The median TTAS was 38.6 hours shorter (95% confidence interval: −2.6, 68.4) in the baloxavir group compared with placebo (median TTAS, 54.1 hours vs 92.7 hours, P =.0055). The median time to sustained cessation of infectious virus detection was 72.0 hours for baloxavir compared with 120.0 hours for placebo recipients (P <.0001). Treatment-emergent PA/I38X-substituted viruses were detected in 5 of the 51 (9.8%) baloxavir recipients. In the safety population (76 baloxavir and 41 placebo), AEs were less common in baloxavir than placebo recipients (17.1% vs 34.1%; P =.0421). In the baloxavir group, no AEs except for diarrhea were reported in 2 or more patients. Conclusions Baloxavir demonstrated clinical and virologic efficacy in the otherwise healthy adolescents with acute influenza compared with placebo. There were no safety concerns identified. These results were similar to the adult population in CAPSTONE-1 and support baloxavir as a treatment option in adolescents. [ABSTRACT FROM AUTHOR]

Antivirals, respiratory syncytial virus, therapeutics. [Extracted from the article]

The possible effects of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) on COVID-19 disease severity have generated considerable debate. We performed a single-center, retrospective analysis of hospitalized adult COVID-19 patients in Wuhan, China, who had definite clinical outcome (dead or discharged) by February 15, 2020. Patients on anti-hypertensive treatment with or without ACEI/ARB were compared on their clinical characteristics and outcomes. The medical records from 702 patients were screened. Among the 101 patients with a history of hypertension and taking at least one anti-hypertensive medication, 40 patients were receiving ACEI/ARB as part of their regimen, and 61 patients were on antihypertensive medication other than ACEI/ARB. We observed no statistically significant differences in percentages of in-hospital mortality (28% vs. 34%, P = 0.46), ICU admission (20% vs. 28%, P = 0.37) or invasive mechanical ventilation (18% vs. 26%, P = 0.31) between patients with or without ACEI/ARB treatment. Further multivariable adjustment of age and gender did not provide evidence for a significant association between ACEI/ARB treatment and severe COVID-19 outcomes. Our findings confirm the lack of an association between chronic receipt of renin-angiotensin system antagonists and severe outcomes of COVID-19. Patients should continue previous anti-hypertensive therapy until further evidence is available. [ABSTRACT FROM AUTHOR]

Background: A synergistic effect of combination therapy with favipiravir and oseltamivir has been reported in preclinical models of influenza. However, no data are available on the clinical effectiveness of combination therapy in severe influenza.Methods: Data from 2 separate prospective studies of influenza adults were used to compare outcomes between combination and oseltamivir monotherapy. Outcomes included rate of clinical improvement (defined as a decrease of 2 categories on a 7-category ordinal scale) and viral RNA detectability over time. Subhazard ratios (sHRs) were estimated by the Fine and Gray model for competing risks.Results: In total, 40 patients were treated with combination therapy and 128 with oseltamivir alone. Clinical improvement on day 14 in the combination group was higher than in the monotherapy group (62.5% vs 42.2%; P = .0247). The adjusted sHR for combination therapy was 2.06 (95% confidence interval, 1.30-3.26). The proportion of undetectable viral RNA at day 10 was higher in the combination group than the oseltamivir group (67.5% vs 21.9%; P < .01). No significant differences were observed in mortality or other outcomes.Conclusions: Favipiravir and oseltamivir combination therapy may accelerate clinical recovery compared to oseltamivir monotherapy in severe influenza, and this strategy should be formally evaluated in a randomized controlled trial. [ABSTRACT FROM AUTHOR]

With the expanding use of molecular assays, viral pathogens are increasingly recognized among critically ill adult patients with community-acquired severe respiratory illness; studies have detected respiratory viral infections (RVIs) in 17-53% of such patients. In addition, novel pathogens including zoonotic coronaviruses like the agents causing Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS) and the 2019 novel coronavirus (2019 nCoV) are still being identified. Patients with severe RVIs requiring ICU care present typically with hypoxemic respiratory failure. Oseltamivir is the most widely used neuraminidase inhibitor for treatment of influenza; data suggest that early use is associated with reduced mortality in critically ill patients with influenza. At present, there are no antiviral therapies of proven efficacy for other severe RVIs. Several adjunctive pharmacologic interventions have been studied for their immunomodulatory effects, including macrolides, corticosteroids, cyclooxygenase-2 inhibitors, sirolimus, statins, anti-influenza immune plasma, and vitamin C, but none is recommended at present in severe RVIs. Evidence-based supportive care is the mainstay for management of severe respiratory viral infection. Non-invasive ventilation in patients with severe RVI causing acute hypoxemic respiratory failure and pneumonia is associated with a high likelihood of transition to invasive ventilation. Limited existing knowledge highlights the need for data regarding supportive care and adjunctive pharmacologic therapy that is specific for critically ill patients with severe RVI. There is a need for more pragmatic and efficient designs to test different therapeutics both individually and in combination. [ABSTRACT FROM AUTHOR]

Background: Single-dose baloxavir rapidly reduces influenza virus titers and symptoms in patients with uncomplicated influenza, but viruses with reduced in vitro susceptibility due to amino acid substitutions at position 38 of polymerase acidic protein (PA/I38X) sometimes emerge.Methods: We evaluated the kinetics, risk factors, and effects on clinical and virologic outcomes of emergence of PA/I38X-substituted viruses.Results: Viruses containing PA/I38X substitutions were identified 3-9 days after baloxavir treatment in 9.7% (36/370) of patients, of whom 85.3% had transient virus titer rises. Median time to sustained cessation of infectious virus detection was 192, 48, and 96 hours in the baloxavir recipients with PA/I38X-substituted viruses, without PA/I38X-substituted viruses, and placebo recipients, respectively. The corresponding median times to alleviation of symptoms were 63.1, 51.0, and 80.2 hours, respectively. After day 5, symptom increases occurred in 11.5%, 8.0%, and 13.0%, respectively, and in 8.9% of oseltamivir recipients. Variant virus emergence was associated with lower baseline neutralizing antibody titers.Conclusions: The emergence of viruses with PA/I38X substitutions following baloxavir treatment was associated with transient rises in infectious virus titers, prolongation of virus detectability, initial delay in symptom alleviation, and uncommonly with symptom rebound. The potential transmissibility of PA/I38X-substituted viruses requires careful study.Clinical Trial Registration: NCT02954354. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Severe influenza infection represents a leading cause of global morbidity and mortality. Although influenza is primarily considered a viral infection that results in pathology limited to the respiratory system, clinical reports suggest that influenza infection is frequently associated with a number of clinical syndromes that involve organ systems outside the respiratory tract. A comprehensive MEDLINE literature review of articles pertaining to extra-pulmonary complications of influenza infection, using organ-specific search terms, yielded 218 articles including case reports, epidemiologic investigations, and autopsy studies that were reviewed to determine the clinical involvement of other organs. The most frequently described clinical entities were viral myocarditis and viral encephalitis. Recognition of these extra-pulmonary complications is critical to determining the true burden of influenza infection and initiating organ-specific supportive care. [ABSTRACT FROM AUTHOR]

The article focuses on experimental therapies that are used in the treatment of Ebola virus disease (EVD). Various topics discussed include mortality rate of EVD, supportive care offered to patients suffering from EVD, child's survival through these therapies and use of antiviral agents in the treatment.

We explored the feasibility of collecting convalescent plasma for passive immunotherapy of Middle East respiratory syndrome coronavirus (MERS-CoV) infection by using ELISA to screen serum samples from 443 potential plasma donors: 196 patients with suspected or laboratory-confirmed MERS-CoV infection, 230 healthcare workers, and 17 household contacts exposed to MERS-CoV. ELISA-reactive samples were further tested by indirect fluorescent antibody and microneutralization assays. Of the 443 tested samples, 12 (2.7%) had a reactive ELISA result, and 9 of the 12 had reactive indirect fluorescent antibody and microneutralization assay titers. Undertaking clinical trials of convalescent plasma for passive immunotherapy of MERS-CoV infection may be feasible, but such trials would be challenging because of the small pool of potential donors with sufficiently high antibody titers. Alternative strategies to identify convalescent plasma donors with adequate antibody titers should be explored, including the sampling of serum from patients with more severe disease and sampling at earlier points during illness. [ABSTRACT FROM AUTHOR]

This review highlights the main points which emerged from the presentations and discussions at the 3rd isirv- Antiviral Group Conference - advances in clinical management. The conference covered emerging and potentially pandemic influenza viruses and discussed novel/pre-licensure therapeutics and currently approved antivirals and vaccines for the control of influenza. Current data on approved and novel treatments for non-influenza respiratory viruses such as MERS- Co V, respiratory syncytial virus ( RSV) and rhinoviruses and the challenges of treating immunocompromised patients with respiratory infections was highlighted. [ABSTRACT FROM AUTHOR]

Progress in the development of antivirals for non-influenza respiratory viruses has been slow with the result that many unmet medical needs and few approved agents currently exist. This commentary selectively reviews examples of where specific agents have provided promising clinical benefits in selected target populations and also considers potential therapeutics for emerging threats like the SARS and Middle East respiratory syndrome coronaviruses. Recent studies have provided encouraging results in treating respiratory syncytial virus infections in lung transplant recipients, serious parainfluenza virus and adenovirus infections in immunocompromised hosts, and rhinovirus colds in outpatient asthmatics. While additional studies are needed to confirm the efficacy and safety of the specific agents tested, these observations offer the opportunity to expand therapeutic studies to other patient populations. [ABSTRACT FROM AUTHOR]

Emergence of resistance is a major concern in influenza antiviral treatment and prophylaxis. Combination antiviral therapy might overcome this problem. Here, we estimate that all possible single mutants and a sizeable fraction of double mutants are generated during an uncomplicated influenza infection. While most of them may sustain a fitness cost, some variants may confer drug resistance and be selected during therapy. We argue that a triple combination regimen would markedly reduce the risk of antiviral resistance emergence in seasonal and pandemic influenza viruses, especially in seriously ill or immunocompromised hosts. [ABSTRACT FROM AUTHOR]

Emergence of resistance is a major concern in influenza antiviral treatment and prophylaxis. Combination antiviral therapy might overcome this problem. Here, we estimate that all possible single mutants and a sizeable fraction of double mutants are generated during an uncomplicated influenza infection. While most of them may sustain a fitness cost, some variants may confer drug resistance and be selected during therapy. We argue that a triple combination regimen would markedly reduce the risk of antiviral resistance emergence in seasonal and pandemic influenza viruses, especially in seriously ill or immunocompromised hosts. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Belser et al. (2011) XIth International Symposium on Respiratory Viral Infections. Influenza and Other Respiratory Viruses 5(6), 443-e457. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Howard et al. (2011) Report of the 'Mechanisms of lung injury and immunomodulator interventions in influenza' workshop, 21 March 2010, Ventura, California, USA*. Influenza and Other Respiratory Viruses 5(6), 453-e475. The clinical course of influenza and the extent of lung injury are determined by both viral and host factors, as well as sometimes secondary bacterial infections and exacerbations of underlying conditions. The balance between viral replication and the host immune responses is central to disease pathogenesis, and the extent of lung injury in severe influenza infections may be due in part to overly exuberant or dysregulated innate inflammatory responses or sometimes deficient responses. Acute respiratory distress syndrome (ARDS) is the principal cause of respiratory failure associated with severe influenza. ARDS can be triggered by both direct lung insults (e.g. respiratory pathogens) and systemic insults (e.g. sepsis), and the lung damage is exacerbated by the inflammatory response associated with either infectious or non-infectious insults. This workshop aimed to review the current understanding of lung injury in acute influenza and describe cellular and molecular mechanisms of lung injury that are common to influenza and infections by other respiratory pathogens. In addition, therapeutic agents that target host response proteins and pathways were identified and investigational agents in development reviewed. A logical strategy would be to combine antiviral treatment with drugs that modify excessive host responses or supplement deficient ones. However, a better understanding of common cell signalling pathways associated with acute lung injury caused by influenza and other pathogens is necessary to understand immunopathologic causes of lung injury. This will help determine which immunomodulatory interventions might be useful, and to predict the appropriate timing and consequences of their use. [ABSTRACT FROM AUTHOR]

Influenza infection results in substantial morbidity and mortality in hospitalized patients, including those who are immunocompromised or pregnant. Antiviral therapy likely provides considerable benefit to these patients, but few studies have been successfully conducted in these high-risk populations, and no drugs are specifically licensed for treating these subgroups. One of the key challenges facing novel antiviral drug development for influenza is determining the appropriate efficacy end points that would enable rapid regulatory approval for drug use in seriously ill patients, for whom risk-benefit assessments differ from those with uncomplicated illness. All available antiviral drugs currently affect viral replication, and respiratory tract viral titers correlate with both symptoms and measures of host inflammatory responses, including cytokine and chemokine expression that are likely responsible for many of the clinical symptoms. Consequently, we outline the evidence to support the use of primary virological end points in studies of antiviral agents involving patients who are hospitalized with severe influenza or those who are at high risk of severe and life-threatening disease. [ABSTRACT FROM AUTHOR]

We report acute encephalopathy associated with influenza A infection in 3 adults. We detected high cerebrospinal fluid (CSF) and plasma concentrations of CXCL8/IL-8 and CCL2/MCP-1 (CSF/plasma ratios > or =3), and interleukin-6, CXCL10/IP-10, but no evidence of viral neuroinvasion. Patients recovered without sequelae. Hyperactivated cytokine response may play a role in pathogenesis. [ABSTRACT FROM AUTHOR]

We report acute encephalopathy associated with influenza A infection in 3 adults. We detected high cerebrospinal fluid (CSF) and plasma concentrations of CXCL8/IL-8 and CCL2/MCP-1 (CSF/plasma ratios >3), and interleukin-6, CXCL10/IP-10, but no evidence of viral neuroinvasion. Patients recovered without sequelae. Hyperactivated cytokine response may play a role in pathogenesis. [ABSTRACT FROM AUTHOR]

The author discusses the gain-of-function (GOF) research with potential pandemic pathogens and the Infectious Diseases Society of America (IDSA). He discusses the importance of clinician perspective for risk-benefit assessment (RBA) of GOF research. The author mentioned the recommendations from the National Science Advisory Board for Biosecurity (NSABB) on the dual use and biosecurity of GOF.

The availability of immunogenic, licensed H5N1 vaccines and the anticipated development of vaccines against "swine" influenza A(H1N1) have stimulated debate about the possible use of these vaccines for protection of those exposed to potential pandemic influenza viruses and for immunization or "priming" of populations in the so-called "prepandemic" (interpandemic) era. However, the safety of such vaccines is a critical issue in policy development for wide-scale application of vaccines in the interpandemic period. For example, wide-scale interpandemic use of H5N1 vaccines could lead to millions of persons receiving vaccines of uncertain efficacy potentially associated with rare severe adverse events and against a virus that may not cause a pandemic. Here, we first review aspects of the 1976 National Influenza Immunization Programme against "swine flu" and its well-documented association with Guillain-Barré syndrome as a case study illustration of a suspected vaccine-associated severe adverse event in a mass interpandemic immunization setting. This case study is especially timely, given the recent spread of a novel influenza A(H1N1) virus in humans in Mexico and beyond. Following this, we examine available safety data from clinical trials of H5N1 vaccines and briefly discuss how vaccine safety could be monitored in a postmarketing surveillance setting. [ABSTRACT FROM AUTHOR]

The availability of immunogenic, licensed H5N1 vaccines and the anticipated development of vaccines against "swine" influenza A(H1N1) have stimulated debate about the possible use of these vaccines for protection of those exposed to potential pandemic influenza viruses and for immunization or "priming" of populations in the so-called "prepandemic" (interpandemic) era. However, the safety of such vaccines is a critical issue in policy development for wide-scale application of vaccines in the interpandemic period. For example, wide-scale interpandemic use of H5N1 vaccines could lead to millions of persons receiving vaccines of uncertain efficacy potentially associated with rare severe adverse events and against a virus that may not cause a pandemic. Here, we first review aspects of the 1976 National Influenza Immunization Programme against "swine flu" and its well-documented association with Guillain-Barré syndrome as a case study illustration of a suspected vaccine-associated severe adverse event in a mass interpandemic immunization setting. This case study is especially timely, given the recent spread of a novel influenza A(H1N1) virus in humans in Mexico and beyond. Following this, we examine available safety data from clinical trials of H5N1 vaccines and briefly discuss how vaccine safety could be monitored in a postmarketing surveillance setting. [ABSTRACT FROM AUTHOR]

Guidelines for the treatment of persons with influenza virus infection were prepared by an Expert Panel of the Infectious Diseases Society of America. The evidence-based guidelines encompass diagnostic issues, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal (interpandemic) influenza. They are intended for use by physicians in all medical specialties with direct patient care, because influenza virus infection is common in communities during influenza season and may be encountered by practitioners caring for a wide variety of patients. [ABSTRACT FROM AUTHOR]

Background. Respiratory syncytial virus (RSV) has been recognized recently as an important adult pathogen. Methods. This randomized, double-blind, placebo-controlled study was designed to compare humoral responses to licensed trivalent influenza vaccine given concomitantly with 1 of 2 RSV vaccine formulations in persons ⩾65 years old with cardiopulmonary disease. Hemagglutinin-inhibition assays and neutralization assays were used to measure levels of antibody to influenza and RSV, respectively. Subjects with respiratory illnesses during subsequent winters were tested for RSV and influenza by reverse-transcriptase polymerase chain reaction and serologic analysis. Results. Neither RSV vaccine formulation had an effect on the humoral response to influenza vaccination, and both RSV vaccines were well tolerated by 1169 participants. The immunogenicity of the nonadjuvanted vaccine was judged superior on the basis of mean postvaccination neutralizing antibody titers (12.5 vs. 12.1) and the percentage of subjects for whom ⩾4-fold increases in neutralizing titer were observed when acute-phase and convalescent-phase serum samples were compared (168 [44%] of 383 vs. 129 [33%] of 400). In year 1, the percentage of illnesses due to RSV was 7% (36 of 492 illnesses) and that due to influenza was 8%(40 of 492), compared with 6% (11 of 189) due to RSV and 11% (20 of 189) due to influenza in year 2. The incidence of RSV infection was not significantly different in the RSV vaccine and placebo groups. Conclusions. Although the safety and immunogenicity data of these RSV vaccines are encouraging, low rates of infection make it challenging to design efficacy trials. [ABSTRACT FROM AUTHOR]

Conclusion. Middle ear pressure was affected by respiratory illness and season; picornavirus (without illness) or pathogenic bacteria in the nasopharynx had no or minor effect. Objective. To examine the effect of respiratory illness, season, and nasopharyngeal microbial flora on middle ear pressure. Subjects and methods. Thirteen children were followed longitudinally with daily recording of respiratory symptoms, weekly tympanometry, and weekly testing of nasal aspirate/washes for Streptococcus pneumoniae, Hemophilus influenzae, Moraxella catarrhalis by culture and for picornavirus by RT-PCR. Results. Abnormal middle ear pressure was present at 47% of 473 weekly visits by 11 preschool age (≤5years) vs 28% of 212 visits by 2 school age children. Symptomatic illness predicted abnormal middle ear pressure (63% of 107 ill visits in preschoolers vs 43% of 366 well visits, p<0.004). Abnormal tympanometry in preschoolers at well visits rose from 26% (80 visits) in summer to 54% (100 visits) in spring (p≤0.03). No increase in abnormal tympanometry occurred during 18 picornavirus infections without illness. The presence of one or more of the bacterial species at ill or well visits had no effect on middle ear pressure except for a 12% increase (p=0.008) in abnormal tympanometry associated with H. influenzae at well visits in preschoolers. [ABSTRACT FROM AUTHOR]

The long history of influenza drug development has both contributed practical advances in antiviral chemotherapy and improved the understanding of influenza pathogenesis and epidemiology. The role played by these antivirals continues to grow with the dual threats of seasonal and pandemic influenza. The neuraminidase inhibitors are proven effective for the chemoprophylaxis and treatment of influenza A and B, although early therapy is essential for disease mitigation. Studies of topically applied zanamivir have demonstrated the importance of viral replication in the lower respiratory tract, even in uncomplicated influenza. Antiviral resistance, especially to the M2 ion channel inhibitors, sometimes limits clinical utility. Oseltamivir-resistant variants may emerge during treatment but have not yet circulated widely and are usually less fit than wild-type virus; most retain susceptibility to zanamivir. The transmission fitness cost of these resistant variants is drug-, neuraminidase subtype-, and mutation-specific. Continued vigilance in drug resistance surveillance is imperative, as is research into the development of new agents that will provide the potential for alternative and combination antiviral therapy. [ABSTRACT FROM AUTHOR]

Context: A high priority in vaccine research is the development of influenza vaccines that do not use embryonated eggs as the substrate for vaccine production.Objective: To determine the dose-related safety, immunogenicity, and protective efficacy of an experimental trivalent influenza virus hemagglutinin (rHA0) vaccine produced in insect cells using recombinant baculoviruses.Design, Setting, and Participants: Randomized, double-blind, placebo-controlled clinical trial at 3 US academic medical centers during the 2004-2005 influenza season among 460 healthy adults without high-risk indications for influenza vaccine.Interventions: Participants were randomly assigned to receive a single injection of saline placebo (n = 154); 75 microg of an rHA0 vaccine containing 15 microg of hemagglutinin from influenza A/New Caledonia/20/99(H1N1) and influenza B/Jiangsu/10/03 virus and 45 microg of hemagglutinin from influenza A/Wyoming/3/03(H3N2) virus (n = 153); or 135 microg of rHA0 containing 45 microg of hemagglutinin each from all 3 components (n = 153). Serum samples were taken before and 30 days following immunization.Main Outcome Measures: Primary safety end points were the rates and severity of solicited and unsolicited adverse events. Primary immunogenicity end points were the rates of 4-fold or greater increases in serum hemagglutinin inhibition antibody to each of the 3 vaccine strains before and 28 days after inoculation. The prespecified primary efficacy end point was culture-documented influenza illness, defined as development of influenza-like illness associated with influenza virus on a nasopharyngeal swab.Results: Rates of local and systemic adverse effects were low, and the rates of systemic adverse effects were not different in either vaccine group than in the placebo group. Hemagglutinin inhibition antibody responses to the H1 component were seen in 3% of placebo, 51% of 75-microg vaccine, and 67% of 135-microg vaccine recipients, while responses to B were seen in 4% of placebo, 65% of 75-microg vaccine, and 92% of 135-microg vaccine recipients. Responses to the H3 component occurred in 11% of placebo, 81% of 75-microg vaccine, and 77% of 135-microg vaccine recipients. Influenza infections in the study population were due to influenza B and A(H3N2), and influenza A infections were A/California/7/2004-like viruses, an antigenically drifted strain. Seven cases of culture-confirmed CDC-defined influenza-like illness occurred in 153 placebo recipients (4.6%) compared with 2 cases (1.3%) in 150 recipients of 75 microg of vaccine, and 0 cases in recipients of 135 microg of vaccine.Conclusions: In this study, a trivalent rHA0 vaccine was safe and immunogenic in a healthy adult population. Preliminary evidence of protection against a drifted influenza A(H3N2) virus was obtained, but the sample size was small. Inclusion of a neuraminidase component did not appear to be required for protection.Trial Registration: clinicaltrials.gov Identifier: NCT00328107. [ABSTRACT FROM AUTHOR]

The article presents a randomized controlled trial that examined the safety, immunogenicity, and efficacy of a trivalent influenza virus hemagglutinin vaccine that was produced in insect cells using recombinant baculoviruses. The authors of the study found that the vaccine was safe and immunogenic in a healthy population of adults. They also found preliminary evidence that showed the vaccine had a protective effect against a drifted influenza A virus. The inclusion of a neuraminidase component was not required for the protective effect.

There is a continued need to improve the state of preparedness for a potential influenza pandemic in the United States despite the publication of a pandemic influenza plan by the Department of Health and Human Services. Of particular importance are the sense of urgency for a coordinated response plan, an allocation of adequate funds to deal with this issue, and the need for a national leader to coordinate the development and execution of a national plan, including its relationship to the control of seasonal influenza. In addition, an infrastructure needs to be established in the United States to enable the rapid development and large-scale production of a safe and effective vaccine for new influenza strains; methods to treat influenza pneumonia need to be evaluated; a coordinated public health response needs to be defined; a nationally developed blueprint to deal with logistics of pandemic prevention is required; and there is a need to establish reliable communication systems on a national and local basis, to provide accurate information to the lay public, health care workers, and the agricultural sector. [ABSTRACT FROM AUTHOR]

The goals of antiviral treatment for influenza are to decrease symptoms and functional disability and, more important, to decrease associated complications, hospitalizations, and mortality. Four drugs have been approved for treatment of and prophylaxis against influenza in the United States, but they are underutilized. The M2 ion channel inhibitors amantadine and rimantadine are effective for prophylaxis, and they decrease the duration of symptoms if they are used for early treatment of influenza A. The rapid emergence of resistance during therapy and, recently, the circulation of resistant H3N2 viruses in the community have decreased the usefulness of these M2 ion channel inhibitors. Early therapy with neuraminidase (NA) inhibitors, either oseltamivir or zanamivir, reduces the duration of symptoms, the duration of disability, and the risk of lower respiratory tract complications. Oseltamivir has been shown to decrease antibiotic use, the number of hospitalizations, and, probably, the risk of death after influenza. NA inhibitors might provide substantial benefits in the treatment of pandemic influenza, with reductions in the numbers of hospitalizations and deaths occurring if such treatment (1) is made available in sufficient time, through rapid distribution, and (2) is available in sufficient quantities as a result of stockpiling. Both of the aforementioned NA inhibitors are highly effective for prophylaxis. Geographically targeted mass chemoprophylaxis might contain the spread of a pandemic virus, but multiple hurdles to successful implementation exist. Resistance to oseltamivir occurs with the H274Y variant in viruses that contain N1; however, to date, such variants have been less fit, have not been transmitted from person to person, and have retained susceptibility to zanamivir. Alternative agents and approaches, including parenteral and combination therapy, for the treatment of influenza are needed in the near and long term. [ABSTRACT FROM AUTHOR]

Background. Staphylococcus aureus is among the most important pathogens in today's hospital setting. Methods. The effects of sneezing on the airborne dispersal of S. aureus and other bacteria were assessed in 11 healthy nasal S. aureus carriers with experimentally induced rhinovirus colds. Airborne dispersal was studied by volumetric air sampling in 2 chamber sessions with and without histamine-induced sneezing. After 2 days of preexposure measurements, volunteers were inoculated with a rhinovirus and monitored for 14 days. Daily quantitative nasal- and skin-culture samples for bacteria and nasal-culture samples for rhinovirus were obtained, cold symptoms were assessed, and volunteer activities were recorded during sessions. Results. All participants developed a cold. Sneezing caused a 4.7-fold increase in the airborne dispersal of S. aureus, a 1.4-fold increase in coagulase-negative staphylococci (CoNS), and a 3.9-fold increase in other bacteria (P < .001). An additional 2.83 colony forming units (cfu) of S. aureus/m³/min, 3.24 cfu of CoNS/m³/min, and 474.61 cfu of other bacteria/m³/min were released per sneeze. Rhinovirus exposure did not change the frequency of sneezing or airborne dispersal. Having respiratory allergies increased the spread of S. aureus by 3.8-fold during sneezing sessions (P < .001). Conclusion. Nasal S. aureus carriers disperse a significant amount of S. aureus into the air by sneezing. Experimental colds do not alter bacterial dispersal, but respiratory allergies multiply the effect of dispersing S. aureus. [ABSTRACT FROM AUTHOR]

We developed an immunocompromised murine model of influenza virus infection and demonstrated comparable efficacy of oral oseltamivir and A-322278 (both given at dosages of 10 mg/kg/day) in reducing viral replication, decreasing weight loss, and prolonging survival. Once the treatment was discontinued, severe combined immunodeficient (SCID) mice had progressive viral replication and clinical decline. Drug-resistant variants were detected in 4 (29%) of 14 and 2 (13%) of 15 mice (both BALB/c and SCID) treated with oseltamivir or A-322278, respectively; no resistant variants were detected in placebo-treated mice. Amino acid substitutions in the hemagglutinin receptor-binding site at aa 137 or 225 were detected in cloned resistant isolates. A substitution in the neuraminidase (NA) active site (Arg292Lys) was detected in the cloned virus recovered from an oseltamivir-treated mouse. This model would be useful for elucidation of the molecular mechanisms of resistance to NA inhibitors and for testing of anti-influenza therapy options that might prevent the emergence of resistant variants. [ABSTRACT FROM AUTHOR]

Influenza virus with resistance to antiviral drugs emerges with increased frequency in immunocompromised patients and can limit the benefit of M2 and neuraminidase (NA) inhibitors. We document 3 cases of influenza in severely immunocompromised patients from whom virus variants with molecular markers of resistance to anti-influenza drugs were recovered. Virus variants recovered from 2 patients had mutations in the M2, NA (with a previously recognized Glu119Val NA substitution), and hemagglutinin genes. We describe a novel Asp198Asn NA mutation in an influenza B virus and its decreased susceptibility to both oseltamivir and zanamivir. [ABSTRACT FROM AUTHOR]

OBJECTIVES: To assess the cost effectiveness and cost utility of preventing post-exposure influenza infection using the neuraminidase inhibitor oseltamivir from a healthcare payer’s perspective in the UK.1. Comparison of patients receiving PEP versus patients not receiving PEP and not being treated with oseltamivir should they become infected.2. Comparison of patients receiving PEP versus patients not receiving PEP but being treated with oseltamivir should they become infected.The model was run with an attack rate in household contacts of 8% for the base case, with higher rates (up to 30%, representing pandemic conditions) tested in sensitivity analyses. A societal perspective and other key parameters were tested in sensitivity analysis. The year of costing was 2002. The time span for the model was up to 1 year (including one influenza season), but loss of life was included in the QALY calculation and based on expected life expectancy. METHODS: A simulation model was developed, based on clinical trial results and published data, to predict morbidity and mortality due to influenza and to compare oseltamivir post-exposure prophylaxis (PEP) with no prophylaxis within families with members aged ≥13 years. Two scenarios were tested:1. Comparison of patients receiving PEP versus patients not receiving PEP and not being treated with oseltamivir should they become infected.2. Comparison of patients receiving PEP versus patients not receiving PEP but being treated with oseltamivir should they become infected.The model was run with an attack rate in household contacts of 8% for the base case, with higher rates (up to 30%, representing pandemic conditions) tested in sensitivity analyses. A societal perspective and other key parameters were tested in sensitivity analysis. The year of costing was 2002. The time span for the model was up to 1 year (including one influenza season), but loss of life was included in the QALY calculation and based on expected life expectancy. RESULTS: PEP with oseltamivir results in reduced morbidity (i.e. fewer influenza cases) and associated reductions in complications, hospitalisations and mortality due to influenza. When comparing oseltamivir PEP with no prophylaxis for contact attack rates of 8%, 12% and 30%, the mean costs per QALY gained for scenario one were estimated at £29 938, £18 697 and £5403, respectively; the mean costs per case avoided were £467, £293 and £84, respectively. The corresponding results for scenario two were £52 202, £31 610 and £9688 per QALY gained. CONCLUSIONS: PEP with oseltamivir is likely to be a cost-effective strategy for family contacts in the UK from a healthcare payer perspective when influenza-like illness contact attack rates are 8% or higher and the only treatment given is ‘usual care’. [ABSTRACT FROM AUTHOR]