Efficacy of oseltamivir-peramivir combination therapy compared to oseltamivir monotherapy for Influenza A (H7N9) infection: a retrospective study

Considerations when treating influenza infections with oseltamivir

INTRODUCTION

Since the coronavirus disease 2019-mandated social distancing policy has been lifted worldwide, the circulation of influenza is expected to resume. Currently, oseltamivir is approved as the first-line agent for influenza prevention and treatment.

AREAS COVERED

This paper reviews the updated evidence in the pharmacology, resistance mechanisms, clinical pharmacy management, and real-world data on oseltamivir for influenza.

EXPERT OPINION

Oseltamivir is an oral prodrug of oseltamivir carboxylate, an influenza A and B neuraminidase inhibitor. Recently, the therapeutic efficacy of oseltamivir has been demonstrated in several trials. Oseltamivir is generally well-tolerated but may lead to neuropsychiatric events and bleeding. Oseltamivir-resistant influenza virus has been associated with the H275Y mutation in the influenza A(H1N1)pdm09 virus, while most strains are still sensitive to oseltamivir. Dose adjustment for oseltamivir should be based on creatinine clearance and body weight in pediatric patients with renal failure. According to real-world data from Nanfang Hospital, the annual number of patients prescribed oseltamivir declined from 35,711 in 2019 to 8,971 in 2020, with marked increases in 2022 (20,213) and 2023 (18,071). Among the 206 inpatients, children aged < 6 years who were treated with oseltamivir had the shortest duration to defervescence.

Influenza antivirals and their role in pandemic preparedness

Effective antivirals provide crucial benefits during the early phase of an influenza pandemic, when vaccines are still being developed and manufactured. Currently, two classes of viral protein-targeting drugs, neuraminidase inhibitors and polymerase inhibitors, are approved for influenza treatment and post-exposure prophylaxis. Resistance to both classes has been documented, highlighting the need to develop novel antiviral options that may include both viral and host-targeted inhibitors. Such efforts will form the basis of management of seasonal influenza infections and of strategic planning for future influenza pandemics. This review focuses on the two classes of approved antivirals, their drawbacks, and ongoing work to characterize novel agents or combination therapy approaches to address these shortcomings. The importance of these topics in the ongoing process of influenza pandemic planning is also discussed.

Network pharmacology study to reveal active compounds of Qinggan Yin formula against pulmonary inflammation by inhibiting MAPK activation

ETHNOPHARMACOLOGICAL RELEVANCE

Pneumonia is common and frequently-occurred disease caused by pathogens which predisposes to lung parenchymal inflammation leading pulmonary dysfunction. To prevent and alleviate the symptoms of pneumonia, Qinggan Yin formula (QGY) was composed based on clinical experience and four classical traditional Chinese medicine prescriptions which frequently applied to treat infectious diseases.

AIM OF THE STUDY

Traditional Chinese medicine is a complex mixture and it is difficult to distinguish the effective component molecules. The aim of this study is to identify the compounds of QGY with anti-inflammatory effects and investigate the molecular mechanism.

MATERIALS AND METHODS

The high-resolution mass spectrometry and molecular networking were performed for comprehensive chemical profiling of QGY. Network pharmacology was used to generate "herbal-target-pathway" network for target predictions. The anti-inflammation effects of QGY were evaluated in mice model of lipopolysaccharide (LPS) induced acute inflammation. Tail transected zebrafish was also employed to validate macrophage migration reversed effect of QGY. Based on the molecular enrichment analysis, the active substances of QGY with anti-inflammatory effects were further identified in cellular model of macrophage activation. The mechanisms of active substances were investigated by testing their effects on the expression of correlated proteins by Western blot.

RESULTS

In total, 71 compounds are identified as major substances of QGY. According to the results of network pharmacology, QGY shows moderate anti-inflammatory effects and inhibit pulmonary injury. MAPK signaling pathway was predicted as the most related pathway regulated by QGY. Moreover, QGY significantly inhibit LPS-induced pulmonary inflammation in mice, and reversed macrophage migration toward the injury site in zebrafish. We also validate that some major compounds in QGY significantly attenuated the release of IL-1β, IL-6 and TNF-α in LPS-stimulated macrophage. Those active substances including acacetin and arctiin can inhibit the phosphorylation of ERK/JNK and down-regulated the protein expression of BCL-2.

CONCLUSION

Collectively, QGY possessed pronounced anti-inflammation effects. The integration of network pharmacology and experimental results indicated arctiin, iridin, acacetin, liquiritin, and arctigenin are major active substances of QGY with anti-inflammatory effects. The underlying mechanism of QGY involves MAPK signaling pathway and oxidative stress pathway.

A comparison of demographic, epidemiological and clinical characteristics of hospital influenza-related viral pneumonia patients

Background

Through the comparison of the demographic, epidemiological, and clinical characteristics of hospital human influenza (influenza A (H1N1) pdm09, H3N2, and B)-related and hospitalized avian-origin influenza A (H7N9)-related viral pneumonia patients, find the different between them.

Methods

A retrospective study was conducted in hospitalized influenza-related viral pneumonia patients.

Results

Human influenza A-related patients in the 35–49-year-old group were more than those with B pneumonia patients (p = 0.027), and relatively less in the ≥ 65-year-old group than B pneumonia patients (p = 0.079). The proportion of comorbid condition to human influenza A pneumonia was 58%, lower than B pneumonia and H7N9 pneumonia patients (78% vs. 77.8%; p = 0.013). The proportion of invasive mechanical ventilation (IMV), lymphocytopenia, elevated lactate dehydrogenase to hospitalized human influenza A-related viral pneumonia patients was higher than B pneumonia patients (p < 0.05), but lower than H7N9 pneumonia patients (p < 0.05). In the multivariate analysis, pulmonary consolidation (odds ratio (OR): 13.67; 95% confidence interval (CI) 1.54–121.12; p = 0.019) and positive bacterial culture (sputum) (OR: 7.71; 95% CI 2.48–24.03; p < 0.001) were independently associated with IMV, while shock (OR: 13.16; 95% CI 2.06–84.07; p = 0.006), white blood cell count > 10,000/mm³ (OR: 7.22; 95% CI 1.47–35.58; p = 0.015) and positive bacterial culture(blood or sputum) (OR: 6.27; 95% CI 1.36–28.85; p = 0.018) were independently associated with death in the three types hospitalized influenza-related viral pneumonia patients.

Conclusions

Hospital influenza B-related viral pneumonia mainly affects the elderly and people with underlying diseases, while human influenza A pneumonia mainly affects the young adults; however, the mortality was similar. The hospitalized human influenza A-related viral pneumonia patients was severer than B pneumonia patients, but milder than H7N9 pneumonia patients. Pulmonary consolidation and positive bacterial culture (sputum) were independently associated with IMV, while shock, white blood cell count > 10,000/mm³, and positive bacterial culture (blood or sputum) were independently associated with death to three types hospitalized influenza-related viral pneumonia patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06485-x.

Quantification of Cytokine Storms During Virus Infections

Highly pathogenic virus infections usually trigger cytokine storms, which may have adverse effects on vital organs and result in high mortalities. The two cytokines interleukin (IL)-4 and interferon (IFN)-γ play key roles in the generation and regulation of cytokine storms. However, it is still unclear whether the cytokine with the largest induction amplitude is the same under different virus infections. It is unknown which is the most critical and whether there are any mathematical formulas that can fit the changing rules of cytokines. Three coronaviruses (SARS-CoV, MERS-CoV, and SARS-CoV-2), three influenza viruses (2009H1N1, H5N1 and H7N9), Ebola virus, human immunodeficiency virus, dengue virus, Zika virus, West Nile virus, hepatitis B virus, hepatitis C virus, and enterovirus 71 were included in this analysis. We retrieved the cytokine fold change (FC), viral load, and clearance rate data from these highly pathogenic virus infections in humans and analyzed the correlations among them. Our analysis showed that interferon-inducible protein (IP)-10, IL-6, IL-8 and IL-17 are the most common cytokines with the largest induction amplitudes. Equations were obtained: the maximum induced cytokine (max) FC = IFN-γ FC × (IFN-γ FC/IL-4 FC) (if IFN-γ FC/IL-4 FC > 1); max FC = IL-4 FC (if IFN-γ FC/IL-4 FC < 1). For IFN-γ-inducible infections, 1.30 × log2 (IFN-γ FC) = log10 (viral load) − 2.48 − 2.83 × (clearance rate). The clinical relevance of cytokines and their antagonists is also discussed.

Factors Associated With Fatality Due to Avian Influenza A(H7N9) Infection in China

BACKGROUND

The high case fatality rate of influenza A(H7N9)-infected patients has been a major clinical concern.

METHODS

To identify the common causes of death due to H7N9 as well as identify risk factors associated with the high inpatient mortality, we retrospectively collected clinical treatment information from 350 hospitalized human cases of H7N9 virus in mainland China during 2013-2017, of which 109 (31.1%) had died, and systematically analyzed the patients' clinical characteristics and risk factors for death.

RESULTS

The median age at time of infection was 57 years, whereas the median age at time of death was 61 years, significantly older than those who survived. In contrast to previous studies, we found nosocomial infections comprising Acinetobacter baumannii and Klebsiella most commonly associated with secondary bacterial infections, which was likely due to the high utilization of supportive therapies, including mechanical ventilation (52.6%), extracorporeal membrane oxygenation (14%), continuous renal replacement therapy (19.1%), and artificial liver therapy (9.7%). Age, time from illness onset to antiviral therapy initiation, and secondary bacterial infection were independent risk factors for death. Age >65 years, secondary bacterial infections, and initiation of neuraminidase-inhibitor therapy after 5 days from symptom onset were associated with increased risk of death.

CONCLUSIONS

Death among H7N9 virus-infected patients occurred rapidly after hospital admission, especially among older patients, followed by severe hypoxemia and multisystem organ failure. Our results show that early neuraminidase-inhibitor therapy and reduction of secondary bacterial infections can help reduce mortality.Characterization of 350 hospitalized avian influenza A(H7N9)-infected patients in China shows that age >65 years, secondary bacterial infections, and initiation of neuraminidase-inhibitor therapy after 5 days from symptom onset were associated with increased risk of death.

Effectiveness of neuraminidase inhibitors to prevent mortality in patients with laboratory-confirmed avian influenza A H7N9

OBJECTIVES

Avian influenza virus A(H7N9) remains a threat to humans and has great potential to cause a pandemic in the foreseeable future. Antiviral treatment with neuraminidase inhibitors has been recommended to treat patients with H7N9 infection as early as possible, although evidence-based research on their effectiveness for H7N9 infection is lacking.

METHODS

Data from all laboratory-confirmed cases of H7N9 infection in Zhejiang Province between 2013 and 2017 were retrieved, and time-dependent survival models were used to evaluate the effectiveness of treatment with neuraminidase inhibitors to reduce the risk of mortality.

RESULTS

The final optimal model found no significant association (odds ratio 1.29, 95% confidence interval 0.78-2.15) between time to treatment with neuraminidase inhibitors and survival after controlling for age and white blood cell count. Sensitivity analyses with multiple imputation for missing data concurred with the primary analysis.

CONCLUSIONS

No association was found between treatment with neuraminidase inhibitors and survival in patients with H7N9 infection using various adjusted models and sensitivity analyses of missing data imputations.

Combination treatment with the cap-dependent endonuclease inhibitor baloxavir marboxil and a neuraminidase inhibitor in a mouse model of influenza A virus infection

Objectives

Baloxavir marboxil (formerly S-033188) is a first-in-class, orally available, cap-dependent endonuclease inhibitor licensed in Japan and the USA for the treatment of influenza virus infection. We evaluated the efficacy of delayed oral treatment with baloxavir marboxil in combination with a neuraminidase inhibitor in a mouse model of lethal influenza virus infection.

Methods

The inhibitory potency of baloxavir acid (the active form of baloxavir marboxil) in combination with neuraminidase inhibitors was tested in vitro. The therapeutic effects of baloxavir marboxil and oseltamivir phosphate, or combinations thereof, were evaluated in mice lethally infected with influenza virus A/PR/8/34; treatments started 96 h post-infection.

Results

Combinations of baloxavir acid and neuraminidase inhibitor exhibited synergistic potency against viral replication by means of inhibition of cytopathic effects in vitro. In mice, baloxavir marboxil monotherapy (15 or 50 mg/kg twice daily) significantly and dose-dependently reduced virus titre 24 h after administration and completely prevented mortality, whereas oseltamivir phosphate treatments were not as effective. In this model, a suboptimal dose of baloxavir marboxil (0.5 mg/kg twice daily) in combination with oseltamivir phosphate provided additional efficacy compared with monotherapy in terms of virus-induced mortality, elevation of cytokine/chemokine levels and pathological changes in the lung.

Conclusions

Baloxavir marboxil monotherapy with 96 h-delayed oral dosing achieved drastic reductions in virus titre, inflammatory response and mortality in a mouse model. Combination treatment with baloxavir acid and oseltamivir acid in vitro and baloxavir marboxil and oseltamivir phosphate in mice produced synergistic responses against influenza virus infections, suggesting that treating humans with the combination may be beneficial.

Prophylaxis of ferrets with nitazoxanide and oseltamivir combinations is more effective at reducing the impact of influenza a virus infection compared to oseltamivir monotherapy

Combination therapy is an alternative approach to reduce viral shedding and improve clinical outcomes following influenza virus infections. In this study we used oseltamivir (OST), a neuraminidase inhibitor and nitazoxanide (NTZ), a host directed drug, and found in vitro that the combination of these two antivirals have a synergistic relationship. Using the ferret model of (A/Perth/265/2009, (H1N1)pdm09), virus infections, we found that the combination of NTZ and OST was more effective than either NTZ or OST independently in preventing infection and reducing duration of viral shedding. However, these benefits were only seen if treatment was administered prophylactically, as opposed to therapeutically. We also found that if prophylactically treated ferrets that had detectable virus in the upper respiratory tract, no virus was detected in the lower respiratory tract. This benefit was not observed with NTZ or OST alone. The combination of NTZ and OST enhances the antiviral effect of OST, which is the standard of care in most settings.

Research progress on human infection with avian influenza H7N9

Since the first case of novel H7N9 infection was reported, China has experienced five epidemics of H7N9. During the fifth wave, a highly pathogenic H7N9 strain emerged. Meanwhile, the H7N9 virus continues to accumulate mutations, and its affinity for the human respiratory epithelial sialic acid 2–6 receptor has increased. Therefore, a pandemic is still possible. In the past 6 years, we have accumulated rich experience in dealing with H7N9, especially in terms of virus tracing, epidemiological research, key site mutation monitoring, critical disease mechanisms, clinical treatment, and vaccine development. In the research fields above, significant progress has been made to effectively control the spread of the epidemic and reduce the fatality rate. To fully document the research progress concerning H7N9, we reviewed the clinical and epidemiological characteristics of H7N9, the key gene mutations of the virus, and H7N9 vaccine, thus providing a scientific basis for further monitoring and prevention of H7N9 influenza epidemics.

Influenza A-associated severe pneumonia in hospitalized patients: Risk factors and NAI treatments

OBJECTIVE

The risk factors and the impact of NAI treatments in patients with severe influenza A-associated pneumonia remain unclear.

METHODS

A multicenter, retrospective, observational study was conducted in Zhejiang, China during a severe influenza epidemic in August 2017-May 2018. Clinical records of patients (>14 y) hospitalized with laboratory-confirmed influenza A virus infection and who developed severe pneumonia were compared to those with mild-to-moderate pneumonia. Risk factors related to pneumonia severity and effects of NAI treatments (monotherapy and combination of peramivir and oseltamivir) were analyzed.

RESULTS

202 patients with influenza A-associated severe pneumonia were enrolled, of whom 84 (41.6%) had died. Male gender (OR = 1.782; 95% CI: 1.089-2.917; P = 0.022), chronic pulmonary disease (OR = 2.581; 95% CI: 1.447-4.603; P = 0.001) and diabetes mellitus (OR = 2.042; 95% CI: 1.135-3.673; P = 0.017) were risk factors related to influenza A pneumonia severity. In cox proportional hazards model, severe pneumonia patients treated with double dose oseltamivir (300mg/d) had a better survival rate compared to those receiving a single dose (150 mg/d) (HR = 0.475; 95%CI: 0.254-0.887; P = 0.019). However, different doses of peramivir (300 mg/d vs. 600 mg/d) and combination therapy (oseltamivir-peramivir vs. monotherapy) showed no differences in 60-day mortality (P = 0.392 and P = 0.658, respectively).

CONCLUSIONS

Patients with male gender, chronic pulmonary disease, or diabetes mellitus were at high risk of developing severe pneumonia after influenza A infection. Double dose oseltamivir might be considered in treating influenza A-associated severe pneumonia.

Oseltamivir and baloxavir: Dual treatment for rapidly developing ARDS on a patient with renal disease

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Baloxavir is an antiviral influenza medication with a different mechanism of action and its use in combination with oseltamivir has not been reported on patients with severe renal impairment.

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Immunocompromise patients have a tendency to develop more severe forms of influenza infection. They may benefit from dual therapy.

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Combination therapy may fasten overall recovery time and decrease the time on extracorporeal oxygenation support.

Influenza is an annual epidemic disease that in severe cases can lead to the development of ARDS. Current practice recommends the routine use of neuraminidase inhibitors with emerging evidence for the use of endonuclease inhibitors. We present the case of a 22-year-old female with diabetes and IgG4 tubulo-interstitial nephritis that developed rapidly progressive ARDS from influenza infection requiring ventilatory support and extra corporeal oxygenation in which oseltamivir and baloxavir were used in combination. Patient oxygen requirements and imaging improved significantly after treatment initiation, leading to an overall short period of therapy. We present the first case of a patient treated with this combination in the context of chronic kidney disease.

Benefit of Early Initiation of Neuraminidase Inhibitor Treatment to Hospitalized Patients With Avian Influenza A(H7N9) Virus

Background

The significance of early neuraminidase inhibitor (NAI) therapy for treating influenza A(H7N9) is currently unknown.

Methods

The duration of viral shedding was monitored by reverse-transcription polymerase chain reaction after patients with confirmed H7N9 infection were admitted to the First Affiliated Hospital, Zhejiang University, during April 2013-April 2017. Indices such as the length of hospitalization and mortality were collected, and the correlation between the time of administration of NAI and the severity of disease was systematically analyzed.

Results

One hundred sixty patients with confirmed H7N9 infection were divided into 3 groups according to NAI starting time. Three of 20 (15%) patients for whom NAI was administered within 2 days died compared with 12 of 52 (23.1%) patients who received treatment within 2-5 days and 33 of 88 (37.5%) patients who were treated after 5 days (P < .05). The median durations of viral shedding from NAI therapy initiation was 4.5 days (interquartile range [IQR], 3-9 days) for patients who took antiviral medication within 2 days, which was significantly different from that for patients who took medication within 2-5 days (7.5 days [IQR, 4.25-12.75 days]) or after 5 days (7 days [IQR, 5-10 days]) (P < .05). We found that the duration of viral shedding from NAI therapy was the shortest in spring 2013 (5.5 days) and the longest in winter-spring 2016-2017 (8.5 days) (P < .05), showing a prolonged trend.

Conclusions

Early NAI therapy within 2 days of illness shortened the duration of viral shedding and improved survival in patients with H7N9 viral infection.

Clinical outcomes of patients treated with intravenous zanamivir for severe influenza A(H1N1)pdm09 infection: a case report series

BACKGROUND

Intravenous (IV) zanamivir could be a suitable alternative for the treatment of severe influenza A(H1N1)pdm09 infection in patients who are unable to take oral or inhaled medication, for example, those on mechanical ventilation and extracorporeal membrane oxygenation (ECMO). However, data on the clinical outcomes of such patients is limited.

CASE PRESENTATION

We report the clinical outcomes of four patients who were admitted at the intensive care unit during the 2017-2018 influenza season with severe sepsis (SOFA score > 11) and acute respiratory distress syndrome requiring ECMO and mechanical ventilation. Two patients were immune-compromised. The A(H1N1)pdm09 genome was confirmed by polymerase chain reaction (PCR) on nasopharyngeal specimen swabs prior to administration of IV zanamivir at a dose of 600 mg twice daily. Weekly qualitative PCR analysis was done to monitor viral clearance, with zanamivir treatment being discontinued upon receipt of negative results. In addition, the patients were managed for concomitant multidrug-resistant bacterial infections, with infection resolution confirmed with blood cultures. The median time for zanamivir treatment was 10 days (IQR 10-17). The clinical outcome was favourable with all four patients surviving and improving clinically. All four patients achieved viral clearance of A(H1N1)pdm09 genome, and resolution of multidrug-resistant bacterial infections.

CONCLUSIONS

IV zanamivir could be a good therapeutic option in patients with severe influenza A(H1N1)pdm09 infection who are unable to take oral or aerosolised antiviral medication. We recommend prospective randomized control trials to support this hypothesis.

Muscle weakness associated with H7N9 infection: report of two cases

Background

The emerging avian influenza A (H7N9) virus, a subtype of influenza viruses, was first discovered in March 2013 in China. Infected patients frequently present with pneumonia and acute respiratory disorder syndrome with high rates of intensive care unit admission and death. Neurological complications, such as Guillain–Barré syndrome(GBS), and intensive care unit-acquired weakness, including critical illness polyneuropathy and myopathy, have only rarely been reported previously.

Case presentation

In this study, we report on two Chinese patients with H7N9 severe pneumonia presenting neurological complications. These two patients had non-immune diseases prior to the onset of virus infection. A 56-year-old female patient (case 1) and a 78-year-old female patient (case 2) were admitted because of fever, cough, chest tightness and shortness of breath. These patients were confirmed to have H7N9 infection soon after admission followed by the development of acute respiratory distress syndrome and various severe bacterial and fungal infections. The case 1 patient was found to have muscle weakness in all extremities after withdrawing the mechanical ventilator, and the case 2 patient was found when withdrawing extracorporeal membrane oxygenation, both of these conditions prolonged ventilator-weaning time. Furthermore, the case 1 patient carried the H7N9 virus for a prolonged period, reaching 28 days, and both of them stayed in the hospital for more than two months. A clinical diagnosis of intensive care unit-acquired weakness could be confirmed. However, based on results from electrophysiological testing and needle electromyography of these 2 patients, it is difficult to differentiate critical illness polyneuropathy from GBS, since no lumbar puncture or muscle and nerve biopsy were conducted during hospitalization. Following a long-term comprehensive treatment, the patients’ neurological condition improved gradually.

Conclusions

Although there is great improvement in saving severe patients’ lives from fatal respiratory and blood infections, it is necessary to pay sufficient attention and to use more methods to differentiate GBS from intensive care unit-acquired weakness. This unusual neurological complication could result in additional complications including ventilator associated pneumonia, prolonged hospital stay and then would further increase the death rate, and huge costs.

Fatty Acid Metabolism is Associated With Disease Severity After H7N9 Infection

BACKGROUND

Human infections with the H7N9 virus could lead to lung damage and even multiple organ failure, which is closely associated with a high mortality rate. However, the metabolic basis of such systemic alterations remains unknown.

METHODS

This study included hospitalized patients (n = 4) with laboratory-confirmed H7N9 infection, healthy controls (n = 9), and two disease control groups comprising patients with pneumonia (n = 9) and patients with pneumonia who received steroid treatment (n = 10). One H7N9-infected patient underwent lung biopsy for histopathological analysis and expression analysis of genes associated with lung homeostasis. H7N9-induced systemic alterations were investigated using metabolomic analysis of sera collected from the four patients by using ultra-performance liquid chromatography-mass spectrometry. Chest digital radiography and laboratory tests were also conducted.

FINDINGS

Two of the four patients did not survive the clinical treatments with antiviral medication, steroids, and oxygen therapy. Biopsy revealed disrupted expression of genes associated with lung epithelial integrity. Histopathological analysis demonstrated severe lung inflammation after H7N9 infection. Metabolomic analysis indicated that fatty acid metabolism may be inhibited during H7N9 infection. Serum levels of palmitic acid, erucic acid, and phytal may negatively correlate with the extent of lung inflammation after H7N9 infection. The changes in fatty acid levels may not be due to steroid treatment or pneumonia.

INTERPRETATION

Altered structural and secretory properties of the lung epithelium may be associated with the severity of H7N9-infection-induced lung disease. Moreover, fatty acid metabolism level may predict a fatal outcome after H7N9 virus infection.

Re-understanding anti-influenza strategy: attach equal importance to antiviral and anti-inflammatory therapies

The direct replication of influenza virus is not the only cause of harm to human health; influenza infection leading to a hyper-inflammatory immune response can also result in serious conditions. So, the treatment strategy for influenza needs to keep balance between antivirus and anti-inflammation. Herein, we review the treatment strategies of anti-influenza drugs and traditional Chinese medicines.

Factors Associated With Prolonged Viral Shedding in Patients With Avian Influenza A(H7N9) Virus Infection

Background

Data are limited on the impact of neuraminidase inhibitor (NAI) treatment on avian influenza A(H7N9) virus RNA shedding.

Methods

In this multicenter, retrospective study, data were collected from adults hospitalized with A(H7N9) infection during 2013-2017 in China. We compared clinical features and A(H7N9) shedding among patients with different NAI doses and combination therapies and evaluated factors associated with A(H7N9) shedding, using Cox proportional hazards regression.

Results

Among 478 patients, the median age was 56 years, 71% were male, and 37% died. The median time from illness onset to NAI treatment initiation was 8 days (interquartile range [IQR], 6-10 days), and the median duration of A(H7N9) RNA detection from onset was 15.5 days (IQR, 12-20 days). A(H7N9) RNA shedding was shorter in survivors than in patients who died (P < .001). Corticosteroid administration (hazard ratio [HR], 0.62 [95% confidence interval {CI}, .50-.77]) and delayed NAI treatment (HR, 0.90 [95% CI, .91-.96]) were independent risk factors for prolonged A(H7N9) shedding. There was no significant difference in A(H7N9) shedding duration between NAI combination treatment and monotherapy (P = .65) or between standard-dose and double-dose oseltamivir treatment (P = .70).

Conclusions

Corticosteroid therapy and delayed NAI treatment were associated with prolonged A(H7N9) RNA shedding. NAI combination therapy and double-dose oseltamivir treatment were not associated with a reduced A(H7N9) shedding duration as compared to standard-dose oseltamivir.

The Hemagglutinin A Stem Antibody MEDI8852 Prevents and Controls Disease and Limits Transmission of Pandemic Influenza Viruses

Background

MEDI8852 is a novel monoclonal antibody (mAb) that neutralizes both group I and group II influenza A viruses (IAVs) in vitro. We evaluated whether MEDI8852 was effective for prophylaxis and therapy against representative group I (H5N1) and group II (H7N9) pandemic IAVs in mice and ferrets and could be used to block transmission of influenza H1N1pdm09 in ferrets, compared to an irrelevant control mAb R347 and oseltamivir.

Methods

MEDI8852 was administered to mice and ferrets by intraperitoneal injection at varying doses, 24 hours prior to intranasal infection with H5N1 and H7N9 viruses for prophylaxis, and 24, 48, and 72 hours post-infection for treatment. A comparison with oseltamivir alone and combination of MEDI8852 and oseltamivir was included in some studies. Survival, weight loss, and viral titers were assessed over a 14-day study period. For the transmission study, naive respiratory contact ferrets received MEDI8852 or R347 prior to exposure to ferrets infected with an H1N1pdm09 virus.

Results

MEDI8852 was effective for prophylaxis and treatment of H7N9 and H5N1 infection in mice, with a clear dose-dependent response and treatment with MEDI8852 24, 48, or 72 hours postinfection was superior to oseltamivir for H5N1. MEDI8852 alone was effective treatment for lethal H5N1 infection in ferrets compared to oseltamivir and R347, and MEDI8852 plus oseltamivir was better than oseltamivir alone. MEDI8852 or oseltamivir alone early in infection was equally effective for H7N9 infection in ferrets while the combination yielded similar protection when treatment was delayed. MEDI8852 was able to protect naive ferrets from airborne transmission of H1N1pdm09.

Conclusions

MEDI8852, alone or with oseltamivir, shows promise for prophylaxis or therapy of group I and II IAVs with pandemic potential. Additionally, MEDI8852 blocked influenza transmission in ferrets, a unique finding among influenza-specific mAbs.

Aerosol administration increases the efficacy of oseltamivir for the treatment of mice infected with influenza viruses

Oseltamivir is an influenza neuraminidase inhibitor that along with supportive therapy has shown to help critically ill patients infected with H7N9 and H1N1pdm influenza virus strains to recover from disease. The standard of care recommends the administration of oseltamivir via oral route which represents difficulties in patients with gastrointestinal complications. Here we tested the use of aerosol administration of oseltamivir to treat mice infected with influenza A/H7N9 virus or influenza A/H1N1pdm virus and directly compared this approach to the standard of care, oral administration. Using nose only delivery of aerosolized oseltamivir we observed a significant increase in efficacy of the treatment compared to oral administration characterized by reduced body weight loss, increased survival rate and dose sparing. The preclinical data presented here supports the possibility of using this approach in clinical settings.

The in vivo efficacy of neuraminidase inhibitors cannot be determined from the decay rates of influenza viral titers observed in treated patients

Antiviral therapy is a first line of defence against new influenza strains. Current pandemic preparations involve stock- piling oseltamivir, an oral neuraminidase inhibitor (NAI), so rapidly determining the effectiveness of NAIs against new viral strains is vital for deciding how to use the stockpile. Previous studies have shown that it is possible to extract the drug efficacy of antivirals from the viral decay rate of chronic infections. In the present work, we use a nonlinear mathematical model representing the course of an influenza infection to explore the possibility of extracting NAI drug efficacy using only the observed viral titer decay rates seen in patients. We first show that the effect of a time-varying antiviral concentration can be accurately approximated by a constant efficacy. We derive a relationship relating the true treatment dose and time elapsed between doses to the constant drug dose required to approximate the time- varying dose. Unfortunately, even with the simplification of a constant drug efficacy, we show that the viral decay rate depends not just on drug efficacy, but also on several viral infection parameters, such as infection and production rate, so that it is not possible to extract drug efficacy from viral decay rate alone.