Uncomplicated Influenza Research Articles

Efficacy and safety of ZX-7101A, an inhibitor of influenza cap-dependent endonuclease, in adults with uncomplicated influenza: a randomized, double-blind, placebo-controlled phase 2/3 trial

ObjectivesTo evaluate the efficacy and safety of ZX-7101A: an inhibitor of influenza viral cap-dependent endonuclease, in adults with uncomplicated influenza and explore treatment-emergent resistance. MethodsWe conducted a randomized, double-blind, placebo-controlled, adaptive-design phase 2 and phase 3 studies (ZX-7101A-202) in adults with uncomplicated influenza. Eligible patients were randomized 1:1:1 to receive a single dose of 40 or 80 mg ZX-7101A or placebo, stratified by body weight and baseline composite symptom score. The primary efficacy endpoint was time to alleviation of influenza symptoms (TTAS) in intention-to-treat infected population. ResultsThe phase 2 trial suggested a significantly shorter TTAS for ZX-7101A compared with placebo: the median TTAS of 40 or 80 mg ZX-7101A was 34.7 hours (95% CI, 22.8–43.4; p 0.005) and 45.8 hours (95% CI, 32.0–66.3; p 0.020), compared with 63.6 hours (95% CI, 43.9–93.4) in the placebo group. In the phase 3 trial, the TTAS of both ZX-7101A dose groups was significantly shortened relative to the placebo: the median TTAS was shortened to 48.4 hours (95% CI, 40.5–55.6) for 40 mg and 39.4 hours (95% CI, 35.8–49.3) for 80 mg, compared with 62.9 hours (95% CI, 56.4–69.3) for placebo (p 0.003 and p < 0.001, respectively). In the safety population, ZX-7101A treatment was associated with fewer adverse events, with 41.8% (100/239) in the 40 mg group, 44.2% (106/240) in the 80 mg group, and 53.8% (129/240) in the placebo group. The majority of adverse events were mild or moderate. Emergence of resistance to ZX-7101A through I38T amino acid substitution was detected in 5/122 (4.1%) patients. Discussion: ZX-7101A was an effective treatment for influenza with a single dose of either 40 mg or 80 mg, with more rapid alleviation of influenza symptoms vs. placebo. No safety concerns were identified with single dose treatment of ZX-7101A.

Real-world effectiveness and safety of Baloxavir Marboxil or Oseltamivir in outpatients with uncomplicated influenza A: an ambispective, observational, multi-center study.

Baloxavir Marboxil is a per oral small-molecule antiviral for the treatment of influenza. While the efficacy and safety of Baloxavir Marboxil have been thoroughly characterized across an extensive clinical trial, studies on the effectiveness of Baloxavir Marboxil in a real-world setting are still scarce. We conducted an ambispective, observational, multi-center study that enrolled uncomplicated in-fluenza outpatients treated with Baloxavir Marboxil or Oseltamivir in East China. The primary endpoint was time from treatment to alleviation of all influenza symptoms (TTAIS). The secondary endpoints included time from treatment to alleviation of fever (TTAF) and household transmission during the duration of influenza. A total of 509 patients were enrolled. The median TTAIS in the Baloxavir Marboxil group and the Oseltamivir group was 28.0 h (IQR, 20.0 to 50.0) and 48.0 h (IQR, 30.0 to 67.0), respectively. The median TTAF in the Baloxavir Marboxil group and the Oseltamivir group was 18 h (IQR, 10.0-24.0) and 30.0 h (IQR, 19.0-48.0). In the COX multivariable analysis, Baloxavir Marboxil reduced the duration of influenza symptoms (HR = 1.36 [95%CI:1.12-1.64], p = 0.002) and the duration of fever (HR = 1.93 [95%CI:1.48-2.52], p < 0.001) compared to Oseltamivir. When antiviral drugs were given within 12-48 h after symptom onset, the Baloxavir Marboxil group had a significantly shorter TTAIS compared to the Oseltamivir group. There was no significant difference in the rate of adverse events between the two group (p = 0.555). Baloxavir Marboxil was superior to Oseltamivir in alleviating influenza symptoms in outpatients with uncomplicated influenza. Our findings suggested that compared to Oseltamivir, Baloxavir Marboxil might be more appropriate for patients with influenza 12- 48 h after symptom onset.

Safety and efficacy of onradivir in adults with acute uncomplicated influenza A infection: a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial

Onradivir (ZSP1273) is a novel anti-influenza A virus inhibitor. Preclinical studies show that onradivir can inhibit influenza A H1N1 and H3N2 replication and increase the survival rate of infected animals. In this study, we aimed to evaluate the safety and efficacy of three onradivir dosing regimens versus placebo in outpatients with acute uncomplicated influenza A virus infection. We did a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial at 20 clinical sites in China. Eligible participants were adults (18-65 years) with an influenza-like illness screened by rapid antigen testing at the first clinical visit, had the presence of a fever (axillary temperature ≥38·0°C), and had the presence of at least one moderate systemic and one respiratory symptom within 48 h of symptom onset. Patients were excluded if they were pregnant, allergic to onradivir, or had received any influenza antiviral medication within 7 days before enrolment. Participants were randomly assigned (1:1:1:1) into four groups by an interactive web response system: onradivir 200 mg twice per day group, onradivir 400 mg twice per day group, onradivir 600 mg once per day group, and a matching placebo group. A 5-day oral treatment course was initiated within 48 h after symptoms onset. The primary outcome was the time to alleviate influenza symptoms in the modified intention-to-treat population. Safety was a secondary outcome. We evaluated the patients' self-assessed severity of seven influenza symptoms on a 4-point ordinal scale, and the treatment-emergent adverse events in all patients. This trial is registered with ClinicalTrials.gov, number NCT04024137. Between Dec 7, 2019, and May 18, 2020, a total of 205 patients were screened; of whom, 172 (84%) were randomly assigned to receive onradivir (n=43 in the 200 mg twice per day group; n=43 in the 400 mg twice per day group; and n=43 in the 600 mg once per day group), or placebo (n=42). Median age was 22 years (IQR 20-26). All three onradivir groups showed decreased median time to alleviate influenza symptoms (46·92 h [IQR 24·00-81·38] in the 200 mg twice per day group, 54·87 h [23·67-110·62] in the 400 mg twice per day group, and 40·05 h [17·70-65·82] in the 600 mg once per day) compared with the placebo group (62·87 h [36·40-113·25]). The median difference between the onradivir 600 mg once per day group and the placebo group was -22·82 h (p=0·0330). The most frequently reported treatment-emergent adverse event was diarrhoea (71 [42%] of 171), ranging from 33-65% of the patients in onradivir-treated groups compared with 10% in the placebo group; no serious adverse events were observed. Onradivir showed a safety profile comparable to placebo, as well as higher efficacy than placebo in ameliorating influenza symptoms and lowering the viral load in adult patients with uncomplicated influenza infection, especially the onradivir 600 mg once per day regimen. National Multidisciplinary Innovation Team Project of Traditional Chinese Medicine, National Natural Science Foundation of China, Guangdong Science and Technology Foundation, Guangzhou Science and Technology Planning Project, Emergency Key Program of Guangzhou Laboratory, Macao Science and Technology Development Fund, and Guangdong Raynovent Biotech.

Prospective observational study of baloxavir marboxil in adults and adolescents with uncomplicated influenza from China

IntroductionThere are limited data on the efficacy of baloxavir marboxil (baloxavir) versus oseltamivir in Chinese patients with influenza A.MethodsThis study is an observational real-world investigation encompassing 246 patients (baloxavir, n = 147; oseltamivir, n = 99) confirmed positive for influenza A. The choice between baloxavir and oseltamivir antiviral treatments was determined collaboratively by the clinician and the patient. A thorough comparative analysis was undertaken between the two groups, examining parameters such as the duration of fever and symptoms, viral load dynamics, lymphocyte changes, and enhancements in health-related quality of life (QoL).ResultsNo significant differences were observed in demographic data between the two groups. The duration of fever was significantly shorter in the baloxavir group (P &amp;lt; 0.001). However, the duration of symptoms was not significant different (P = 0.167). Multivariable Cox analysis showed the independent factors affecting duration of fever were baloxavir treatment (HR = 2.033, P &amp;lt; 0.001), fever on day 1 (HR = 0.741, P = 0.010) and CRP level (HR = 1.009, P = 0.039). Moreover, sex (HR= 0.660, P = 0.019) and monocyte count (HR = 1.355, P = 0.018) were independent factors affecting the duration of symptoms. No significant difference in change of health-related quality of life (P &amp;gt; 0.05), positive rate of viral antigen on day 3 (P = 0.477) between the two groups. Remarkably, a mutation was observed in one case on the third-day after baloxavir treatment compared with first-day, from cysteine to serine at position 384 of the PA subunit.ConclusionIn the clinical setting, baloxavir demonstrated comparable clinical benefits to oseltamivir, establishing its efficacy as an effective antiviral therapy for Chinese patients with influenza.

Oral Favipiravir Exposure and Pharmacodynamic Effects in Adult Outpatients With Acute Influenza.

The pharmacokinetics of oral favipiravir and the relationships of plasma concentrations to antiviral effects are incompletely studied in influenza. 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. 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%). 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.

Therapeutic potential of salicylamide derivatives for combating viral infections.

Since time immemorial human beings have constantly been fighting against viral infections. The ongoing and devastating coronavirus disease 2019 pandemic represents one of the most severe and most significant public health emergencies in human history, highlighting an urgent need to develop broad-spectrum antiviral agents. Salicylamide (2-hydroxybenzamide) derivatives, represented by niclosamide and nitazoxanide, inhibit the replication of a broad range of RNA and DNA viruses such as flavivirus, influenza A virus, and coronavirus. Moreover, nitazoxanide was effective in clinical trials against different viral infections including diarrhea caused by rotavirus and norovirus, uncomplicated influenza A and B, hepatitis B, and hepatitis C. In this review, we summarize the broad antiviral activities of salicylamide derivatives, the clinical progress, and the potential targets or mechanisms against different viral infections and highlight their therapeutic potential in combating the circulating and emerging viral infections in the future.

Effect of cellular regeneration and viral transmission mode on viral spread

Illness negatively affects all aspects of life and one major cause of illness is viral infections. Some viral infections can last for weeks; others, like influenza (the flu), can resolve quickly. During infections, uninfected cells can replicate in order to replenish the cells that have died due to the virus. Many viral models, especially those for short-lived infections like influenza, tend to ignore cellular regeneration since many think that uncomplicated influenza resolves much faster than cells regenerate. This research accounts for cellular regeneration, using an agent-based framework, and varies the regeneration rate in order to understand how cell regeneration affects viral infection dynamics under assumptions of different modes of transmission. We find that although the general trends in peak viral load, time of viral peak, and chronic viral load as regeneration rate changes are the same for cell-free or cell-to-cell transmission, the changes are more extreme for cell-to-cell transmission due to limited access of infected cells to newly generated cells.

LC-MS/MS-based metabolite quantitation of the antiviral prodrug baloxavir marboxil, a new therapy for acute uncomplicated influenza, in human plasma: Application to a human pharmacokinetic study

Baloxavir marboxil (BXM) is a novel orally administrated prodrug for the treatment of acute uncomplicated influenza. In the present study, a bioanalytical LC-MS/MS method was developed and validated for the quantification of baloxavir acid (BXA), the active form of baloxavir marboxil in plasma of healthy volunteers using dolutegravir as an internal standard (IS) following plasma protein precipitation with acetonitrile. BXA and the internal standard were chromatographically separated using Waters Xterra® MS C8 column (5 µm, 4.6 × 50 mm) and a mobile phase comprised of 10.0 mM ammonium formate pH 3.5 and acetonitrile (80:20, v/v) delivered at a flow rate of 0.6 mL/min. The transitions of m/z 484.00 → 247.0 and 420.30 → 277.1 for BXA and IS, respectively in multiple reaction monitoring (MRM) mode in a positive ESI interface were used for quantitation through triple-quad mass spectrometry, API 4000. The method linearity was proven across the concentration range of 0.5–200.0 ng/mL, adjusted, and validated completely in accordance with the bioanalytical guidelines of the United States-FDA. Finally, the present method was effectively applied for the pharmacokinetic study of BXA in healthy human volunteers with accepted reproducibility and ruggedness.

Updates in the management of respiratory virus infections in ICU patients: revisiting the non-SARS-CoV-2 pathogens

ABSTRACT Introduction Although viruses are an underestimated cause of community-acquired pneumonias (CAP) and hospital-acquired pneumonias (HAP)/ventilator-associated pneumonias (VAP) in intensive care unit (ICU) patients, they have an impact on morbidity and mortality. Areas covered In this perspective article, we discuss the available data regarding the management of severe influenza CAP and herpesviridae HAP/VAP. We review diagnostic and therapeutic strategies in order to give clear messages and address unsolved questions. Expert opinion Influenza CAP affects yearly thousands of people; however, robust data regarding antiviral treatment in the most critical forms are scarce. While efficacy of oseltamivir has been investigated in randomized controlled trials (RCT) in uncomplicated influenza, only observational data are available in ICU patients. Herpesviridae are an underestimated cause of HAP/VAP in ICU patients. Whilst incidence of herpesviridae identification in samples from lower respiratory tract of ICU patients is relatively high (from 20% to 50%), efforts should be made to differentiate local reactivation from true lung infection. Only few randomized controlled trials evaluated the efficacy of antiviral treatment in herpesviridae reactivation/infection in ICU patients and all were exploratory or negative. Further studies are needed to evaluate the impact of such treatment in specific populations.

Influenza A virus polymerase acidic protein E23G/K substitutions weaken key baloxavir drug-binding contacts with minimal impact on replication and transmission.

Baloxavir marboxil (BXM) is approved for treating uncomplicated influenza. The active metabolite baloxavir acid (BXA) inhibits cap-dependent endonuclease activity of the influenza virus polymerase acidic protein (PA), which is necessary for viral transcription. Treatment-emergent E23G or E23K (E23G/K) PA substitutions have been implicated in reduced BXA susceptibility, but their effect on virus fitness and transmissibility, their synergism with other BXA resistance markers, and the mechanisms of resistance have been insufficiently studied. Accordingly, we generated point mutants of circulating seasonal influenza A(H1N1)pdm09 and A(H3N2) viruses carrying E23G/K substitutions. Both substitutions caused 2- to 13-fold increases in the BXA EC50. EC50s were higher with E23K than with E23G and increased dramatically (138- to 446-fold) when these substitutions were combined with PA I38T, the dominant BXA resistance marker. E23G/K-substituted viruses exhibited slightly impaired replication in MDCK and Calu-3 cells, which was more pronounced with E23K. In ferret transmission experiments, all viruses transmitted to direct-contact and airborne-transmission animals, with only E23K+I38T viruses failing to infect 100% of animals by airborne transmission. E23G/K genotypes were predominantly stable during transmission events and through five passages in vitro. Thermostable PA–BXA interactions were weakened by E23G/K substitutions and further weakened when combined with I38T. In silico modeling indicated this was caused by E23G/K altering the placement of functionally important Tyr24 in the endonuclease domain, potentially decreasing BXA binding but at some cost to the virus. These data implicate E23G/K, alone or combined with I38T, as important markers of reduced BXM susceptibility, and such mutants could emerge and/or transmit among humans.

Pleiotropic Effects of Icariside II on the Cardiovascular System: Novel Applications of Ethnopharmacology in Targeting Vascular Remodeling.

Pleiotropic Effects of Icariside II on the Cardiovascular System: Novel Applications of Ethnopharmacology in Targeting Vascular Remodeling.

Strategies to fight COVID-19: Beyond the difference between SARS-CoV-2 and Influenza virus

Background: Since the outbreak of COVID-19 emerged in Wuhan, China, in December 2019, the epidemic has spread worldwide and posed a great threat to society. Despite great achievements in COVID-19 research, few studies have focused on the similarities and differences between SARS-CoV-2 and influenza viruses. Results: Through a review of the literature on SARS-CoV-2 and influenza viruses, we found that influenza occurs every year, and influenza pandemics occur irregularly. The uncomplicated human influenza viruses primarily affect the larger airways and rarely the alveoli. However, SARS-CoV-2 mainly involves the deep airways and lungs and can cause DAD, leading to severe hypoxemia. In general, SARS-CoV-2 is no less infectious than the influenza virus. However, its destructive power to the lungs is no less than the avian influenza virus. There is currently no clinical vaccine and specific inhibitor against SARS-CoV-2. Conclusions: SASR-CoV-2 damages lung function more severely than the influenza virus, with higher morbidity, mortality, and severe disease rates. Controlling the source of infection, cutting off the route of transmission, and protecting susceptible populations are critical to the fight against SARS-CoV-2.

Severe influenza: is there a role for antiviral combinations?

Neuraminidase inhibitors have been approved for over 20 years and are currently the standard of care for the treatment of influenza. However, meta-analyses have shown only modest benefit of neuraminidase inhibitors for influenza. 1 Dobson J Whitley RJ Pocock S Monto AS Oseltamivir treatment for influenza in adults: a meta-analysis of randomised controlled trials. Lancet. 2015; 385: 1729-1737 Summary Full Text Full Text PDF PubMed Scopus (361) Google Scholar , 2 Muthuri SG Venkatesan S Myles PR et al. Effectiveness of neuraminidase inhibitors in reducing mortality in patients admitted to hospital with influenza A H1N1pdm09 virus infection: a meta-analysis of individual participant data. Lancet Respir Med. 2014; 2: 395-404 Summary Full Text Full Text PDF PubMed Scopus (457) Google Scholar New treatment strategies for severe influenza are urgently required. A novel antiviral, baloxavir marboxil (baloxavir hereafter), was first approved in Japan in 2018, and subsequently in other countries. Baloxavir belongs to a new class of antivirals that inhibit the endonuclease function of the polymerase acidic protein. 3 O'Hanlon R Shaw ML Baloxavir marboxil: the new influenza drug on the market. Curr Opin Virol. 2019; 35: 14-18 Crossref PubMed Scopus (69) Google Scholar In a 2018 clinical trial, 4 Hayden FG Sugaya N Hirotsu N et al. Baloxavir marboxil for uncomplicated influenza in adults and adolescents. N Engl J Med. 2018; 379: 913-923 Crossref PubMed Scopus (407) Google Scholar a single dose of baloxavir produced greater reductions in influenza viral load than did oseltamivir, with equivalent time to symptom alleviation. Combining baloxavir marboxil with standard-of-care neuraminidase inhibitor in patients hospitalised with severe influenza (FLAGSTONE): a randomised, parallel-group, double-blind, placebo-controlled, superiority trialCombining baloxavir with NAIs did not result in superior clinical outcomes compared with NAIs alone. The combination of baloxavir plus NAI was well tolerated. The findings suggest that combination antivirals would not be routinely indicated in clinical practice for hospitalised patients with severe influenza. Full-Text PDF

A Phase 2 Randomized, Double-Blind, Placebo-Controlled Trial of the Monoclonal Antibody MHAA4549A in Patients With Acute Uncomplicated Influenza A Infection.

BackgroundMHAA4549A, a human monoclonal antibody targeting the influenza A hemagglutinin stalk, neutralizes influenza A virus in animal and human volunteer challenge studies. We investigated the safety and tolerability, efficacy, and pharmacokinetics of MHAA4549A in outpatients with acute, uncomplicated influenza A infection.MethodsThis was a phase 2, randomized, double-blind, placebo-controlled trial of single intravenous (IV) doses of 3600 mg or 8400 mg of MHAA4549A or IV placebo in adult outpatients testing positive for influenza A. Patients were enrolled across 35 sites in 6 countries. Randomization and dosing occurred within ≤72 hours of symptom onset; the study duration was 14 weeks. The primary end point was the nature and frequency of adverse events (AEs). Secondary end points included median time to alleviation of all influenza symptoms, effects on nasopharyngeal viral load and duration of viral shedding, and MHAA4549A serum pharmacokinetics.ResultsOf 125 randomized patients, 124 received study treatment, with 99 confirmed positive for influenza A by central testing. The frequency of AEs between the MHAA4549A and placebo groups was similar; nausea was most common (8 patients; 6.5%). MHAA4549A serum exposure was confirmed in all MHAA4549A-treated patients and was dose-proportional. No hospitalizations or deaths occurred. Between the MHAA4549A and placebo groups, no statistically significant differences occurred in the median time to alleviation of all symptoms, nasopharyngeal viral load, or duration of viral shedding.ConclusionsWhile MHAA4549A was safe and well tolerated with confirmed exposure, the antibody did not improve clinical outcomes in patients with acute uncomplicated influenza A infection.

The development and validation of a novel LC-MS/MS method for the simultaneous quantification of Molnupiravir and its metabolite ß-d-N4-hydroxycytidine in human plasma and saliva

In light of the recent global pandemic, Molnupiravir (MPV) or EIDD-2801, developed for the treatment of patients with uncomplicated influenza, is now being trialled for the treatment of infections caused by highly pathogenic coronaviruses, including COVID-19. A sensitive LC-MS/MS method was developed and validated for the simultaneous quantification of MPV and its metabolite ß-d-N4-hydroxycytidine (NHC) in human plasma and saliva. The analytes were extracted from the matrices by protein precipitation using acetonitrile. This was followed by drying and subsequently injecting the reconstituted solutions onto the column. Chromatographic separation was achieved using a polar Atlantis C18 column with gradient elution of 1 mM Ammonium acetate in water (pH4.3) and 1 mM Ammonium acetate in acetonitrile. Analyte detection was conducted in negative ionisation mode using SRM. Analysis was performed using stable isotopically labelled (SIL) internal standards (IS). The m/z transitions were: MPV (328.1→126.0), NHC (258.0→125.9) and MPV-SIL (331.0→129.0), NHC-SIL (260.9→128.9). Validation was over a linear range of 2.5–5000 ng/ml for both plasma and saliva. Across four different concentrations, precision and accuracy (intra- and inter-day) were 15%; and recovery of both analytes from plasma and saliva was between 95% and 100% and 65–86% respectively. Clinical pharmacokinetic studies are underway utilising this method for determination of MPV and its metabolite in patients with COVID-19 infection.

Implementation of a top five list to identify medical overuse in general practice according to patients\u2019 viewpoint in 2019 in France

BackgroundThere is a current trend to reassess the adequacy of care. Establishing top five lists by involving patients is one way to address medical overuse. The objective of this study was to establish a patients’ top five list in general practice in France. The secondary objective was to identify selection criteria.MethodPatients from the web-based cohort GrippeNet.fr were invited to establish their top five list from 15 care procedures previously selected by general practitioners on the basis of medical overuse. The care procedures were presented on a web-interface with guides written with the help of a patient association. A questionnaire was used to explore factors that may have influenced the choices of the participants.ResultsIn total, 691 patients established the following top five list: 1/ Prescription of antibiotics for acute bronchitis, nasopharyngitis, otitis media with effusion, or uncomplicated influenza; 2/ Prescription of benzodiazepine and benzodiazepine-like agents for insomnia, generalised anxiety and all indications for older patients; 3/ Prescription of a homeopathic treatment (Influenzinum) for flu prevention; 4/ Prescription of antitussive or expectorant agents for acute cough or acute bronchitis care; 5/ Prescription of statins for the primary prevention of cardio-vascular risk in older patients. More than 70% of participants gave importance to the recommendations, effectiveness, and tolerance of the care procedures, whereas only half considered the cost.ConclusionThis study is the first to establish a patient’s top-five list in general practice. This list provides direction for deciding the main targets in limiting medical overuse.

Evaluating the fitness of PA/I38T-substituted influenza A viruses with reduced baloxavir susceptibility in a competitive mixtures ferret model

Baloxavir is approved in several countries for the treatment of uncomplicated influenza in otherwise-healthy and high-risk patients. Treatment-emergent viruses with reduced susceptibility to baloxavir have been detected in clinical trials, but the likelihood of widespread occurrence depends on replication capacity and onward transmission. We evaluated the fitness of A/H3N2 and A/H1N1pdm09 viruses with the polymerase acidic (PA) I38T-variant conferring reduced susceptibility to baloxavir relative to wild-type (WT) viruses, using a competitive mixture ferret model, recombinant viruses and patient-derived virus isolates. The A/H3N2 PA/I38T virus showed a reduction in within-host fitness but comparable between-host fitness to the WT virus, while the A/H1N1pdm09 PA/I38T virus had broadly similar within-host fitness but substantially lower between-host fitness. Although PA/I38T viruses replicate and transmit between ferrets, our data suggest that viruses with this amino acid substitution have lower fitness relative to WT and this relative fitness cost was greater in A/H1N1pdm09 viruses than in A/H3N2 viruses.

Neuraminidase inhibitors and single dose baloxavir are effective and safe in uncomplicated influenza: a meta-analysis of randomized controlled trials

ABSTRACT Background Scarce evidence verifying the clinical impact of baloxavir on influenza complications is found. Methods PubMed, Cochrane Library, and Web of Science databases were searched through December 2020. Randomized-controlled trials (RCT) that enrolled patients with laboratory-confirmed influenza receiving neuraminidase inhibitors (NAI) or baloxavir comparing to placebo were assessed. PROSPERO Registration-number: CRD42021226854. Results Twenty-one RCTs (11,697 patients) were included. Antiviral administration significantly reduced time to clinical resolution (mean difference: −21.3 hours) and total influenza-related complications (OR:0.55, 95%CI: 0.42–0.73). Specifically, antivirals significantly decreased bronchitis (OR:0.54, 95%CI: 0.38–0.75), sinusitis (OR:0.51, 95%CI: 0.33–0.78), acute otitis media (OR:0.48, 95%CI: 0.30–0.77), and antibiotic prescription (OR:0.62; 95%CI: 0.48–0.80). A positive trend favored antivirals administration to reduce pneumonia (OR:0.47, 95%CI: 0.16–1.33), or hospitalization rates (OR:0.65; 95%CI: 0.34–1.24) compared to placebo, but did not reach statistical significance. Adverse events (AE) were reported in 11%, 8.9%, and 5.1% of NAIs, placebo and baloxavir recipients, respectively. Compared with NAIs, administration of baloxavir showed non-significantly reduced AEs (OR:0.74, 95%CI: 0.53–1.04). Conclusions Single-dose baloxavir and NAIs were superior to placebo to reduce complications in uncomplicated influenza, with 40% significant reduction in antibiotic prescription. Safety and efficacy of single-dose baloxavir were non-inferior to NAIs.

Specific therapy and emergency prevention of flu

Influenza A and B epidemics, occasionally pandemics, are characterized by high morbidity and mortality rates. In most cases, an uncomplicated disease ends with recovery, but unfavorable outcomes, up to lethal, are possible, especially in premature, low birth weight, infants and young children, old people, pregnant and postpartum women, with chronic diseases, immunocompromised, receiving salicylates and anticoagulants. The use of modern diagnostic methods allows early detection of patients with influenza, distinguishing them from the total number of patients with respiratory infections. This allows you to optimize the timing of the examination, avoid unnecessary prescription of antibiotics, and timely prescribe specific chemotherapy and chemoprophylaxis. During epidemics, in the presence of an epidemiological history, the conclusion of the clinician is decisive for the diagnosis. Vaccination is an excellent method of preventing or relieving the flu. However, in case of an unfavorable course of the disease, in risk groups, in closed groups, it is recommended to use chemotherapy, pre-exposure or post-exposure chemoprophylaxis. Numerous studies have proven the effectiveness of the use of the drug oseltamivir, a specific blocker of the virus neuraminidase. As a result, its replication stops. The drug does not complicate the vaccination, it can be used in vaccinated people, in all age groups, is available in different dosages, and can be used with food. Treatment for uncomplicated influenza lasts 5 days. In certain situations, chemoprophylaxis and chemotherapy with the specific antiviral drug oseltamivir can help control influenza outbreaks in certain populations.

Histone H4 potentiates neutrophil inflammatory responses to influenza A virus: Down-modulation by H4 binding to C-reactive protein and Surfactant protein D.

Neutrophils participate in the early phase of the innate response to uncomplicated influenza A virus (IAV) infection but also are a major component in later stages of severe IAV or COVID 19 infection where neutrophil extracellular traps (NETs) and associated cell free histones are highly pro-inflammatory. It is likely that IAV interacts with histones during infection. We show that histone H4 binds to IAV and aggregates viral particles. In addition, histone H4 markedly potentiates IAV induced neutrophil respiratory burst responses. Prior studies have shown reactive oxidants to be detrimental during severe IAV infection. C reactive protein (CRP) and surfactant protein D (SP-D) rise during IAV infection. We now show that both of these innate immune proteins bind to histone H4 and significantly down regulate respiratory burst and other responses to histone H4. Isolated constructs composed only of the neck and carbohydrate recognition domain of SP-D also bind to histone H4 and partially limit neutrophil responses to it. These studies indicate that complexes formed of histones and IAV are a potent neutrophil activating stimulus. This finding could account for excess inflammation during IAV or other severe viral infections. The ability of CRP and SP-D to bind to histone H4 may be part of a protective response against excessive inflammation in vivo.