Course and complications of influenza A in seniors over 65 years of age.

OBJECTIVES: Influenza A and B viruses cause epidemics every year, with approximately 3-5 million serious cases and about 290,000 to 650,000 deaths worldwide. Most patients die from bacterial complications of influenza. The aim of our study was to describe the clinical pictures of influenza and the development of the complications in seniors over 65 years of age, who were treated in University Hospital Pilsen. The course of the disease and changes in laboratory parameters were evaluated with regard to the method of treatment performed. METHODS: A descriptive retrospective study was performed. Clinical and laboratory data of seniors with the diagnosis of influenza were extracted from electronic medical records and later analysed. The data were processed with Excel 2016 and Statistica. RESULTS: A collection of 261 seniors, of whom 218 were hospitalized and 43 treated in an outpatient setting, has been studied. Patients who later developed complications had elevated values of CRP, procalcitonin, urea, and creatinine. The antiviral drug oseltamivir was administered to 226 of 261 seniors. Forty-seven seniors (18.0%) died from influenza and its complications (severe pneumonia with acute respiratory insufficiency or heart failure). CONCLUSIONS: The course of influenza in seniors was usually more severe and required hospitalization along with antiviral treatment. The mortality rate in the monitored group exceeded 18%. Annual timely vaccination, but also other preventive measures, and maybe considering other risk groups are methods to prevent severe or even fatal cases of influenza.

The Clinical Effectiveness and Tolerability of Oseltamivir in Unvaccinated Pediatric Influenza Patients during Two Influenza Seasons after the COVID-19 Pandemic: The Impact of Comorbidities on Hospitalization for Influenza in Children.

Antiviral therapy such as oseltamivir has been recommended for hospitalized children with suspected and confirmed influenza for almost 20 years. The therapy is officially authorized for newborns two weeks of age or older, however, questions about its safety and effectiveness still surround it. Our goals were to assess the epidemiological features of two consecutive seasonal influenza cases in children following the COVID-19 pandemic; to observe the clinical effectiveness and tolerability of oseltamivir in hospitalized children who were not vaccinated against influenza and had different influenza subtypes, including A(H1N1), A(H3N2), and B; and to identify specific comorbidities associated with influenza in children. We performed an observational study on 1300 children, enrolled between 1 October 2022 and 30 May 2023 and between 1 October 2023 and 4 May 2024, to the IX Pediatric Infectious Diseases Clinical Section of the National Institute of Infectious Diseases "Prof. Dr. Matei Balș". During the 2022-2023 influenza season, 791 pediatric patients tested positive for influenza and received oseltamivir. Of these, 89% (704/791) had influenza A, with 86.4% having subtype A(H1N1) and 13.6% of cases having A(H3N2), and for influenza B, 11% (87/791) of the pediatric patients. Of the total group, 59% were male, and the median age was 2.4 years (1.02-9.28). For the 2023-2024 influenza season, 509 pediatric patients tested positive for influenza, with 56.9% being of the male gender and who were treated with oseltamivir. Of these patients, 81.6% had influenza A and 18.4% had influenza B. Treatment with neuraminidase inhibitors, specifically oseltamivir, 2 mg/kg/dose administered twice daily for 5 days, was well tolerated by the children, and we recorded no deaths. The duration of hospitalization for patients with a fever after the oseltamivir administration was significantly longer for patients with A(H1N1) infection than A(H3N2), during both seasons. We identified more complications in the 2022-2023 season and a decreasing number of influenza B for the 2023-2024 season. Among children with comorbidities, the most common were asthma, gastrointestinal diseases, and metabolic and endocrine diseases. In terms of effectiveness, oseltamivir significantly reduced the intensity of influenza symptoms, thus reducing the number of days of hospitalization (p = 0.001) as well as post-infection complications (p = 0.005) in both groups. In this study, we evaluated the clinical effectiveness of oseltamivir therapy for all influenza types/subtypes in children, and the length of hospitalization. We identified comorbidities associated with the prolonged duration of hospitalization. Influenza vaccination should be the main tool in the prevention of influenza and its complications in children, especially those with comorbidities.

Clinical analysis of influenza in the neonatal intensive care unit.

BACKGROUND: The aim was to investigate the clinical characteristics, treatment and prognosis of neonatal influenza. METHODS: The clinical data of 21 neonates who were diagnosed with influenza and admitted to the neonatal intensive care unit of Henan Provincial Children's Hospital, China, between January 2023 and January 2024 were retrospectively analyzed. RESULTS: A total of 21 patients were admitted, including 14 with influenza A and 7 with influenza B. Eighteen of these patients were reported to have been exposed to family members with respiratory symptoms before hospitalization. Among all the patients' mothers, only 1 received the influenza vaccine during pregnancy. Fifteen newborns had fever, 13 appetite loss, 10 cough, 9 shortness of breath, 9 nasal obstruction, 3 runny nose, 3 vomiting, 2 severe wheezing, 2 choking, 2 diarrhea, 1 bloating, and 1 sputum in the throat. The pulmonary auscultation sounds were coarse in 19 neonates, weak in 2, moist rales were appreciated in 5 and wheezing in 4 of them. The peripheral total white blood cell count was normal in 18 patients and elevated in 3. The C-reactive protein level was normal in all subjects, and the procalcitonin level was elevated in 1. Nineteen patients had pneumonia on chest imaging. All patients were treated with oseltamivir and finally recovered. CONCLUSION: Influenza A is the most common type of neonatal influenza. The clinical symptoms are atypical, and fever is the main symptom. Treatment with oseltamivir is safe and effective, and the prognosis is mostly favorable.

Comparison of the Effectiveness of Baloxavir and Oseltamivir in Outpatients With Influenza B.

This retrospective cohort study analyzed data from a Japanese health insurance database to assess the effectiveness of baloxavir (n = 4822) for preventing severe events compared with oseltamivir (n = 10,523) in patients with influenza B. The primary endpoint was hospitalization incidence (Days 2-14). The secondary endpoints included intravenous antibacterial drug use, pneumonia hospitalization, heart failure hospitalization, inhalational oxygen requirement, and use of other anti-influenza drugs. The hospitalization incidence was significantly lower with baloxavir (0.15% vs. 0.37%; risk ratio: 2.48, 95% confidence interval: 1.13-5.43). Pneumonia and additional anti-influenza therapy were also less frequent with baloxavir, thus supporting its use. Trial Registration: UMIN Clinical Trials Registry Study ID: UMIN000051382.

Characteristics and outcome of influenza-associated encephalopathy/encephalitis among children in China.

BACKGROUND: Influenza-Associated Encephalopathy/Encephalitis (IAE) is characterized by high incidence and poor prognosis. The aim of this study is to describe the clinical features and outcomes of IAE in pediatric patients. METHODS: We performed a retrospective review of hospitalized cases of laboratory-confirmed influenza infection between January 2018 and December 2021. Demographic, clinical, imaging, treatment and outcome data were collected. Statistical analysis was performed using SPSS software. RESULTS: Of 446 children hospitalized with influenza, 71 cases were identified with a diagnosis of IAE. The median age was 3 years and 46 (64.8 %) were younger than 5 years. Only one patient was vaccinated for seasonal influenza. 46 (64.8 %) patients had abnormal electroencephalogram examination and 47 (66.2 %) had abnormal brain MRI or CT findings. 68 (95.8 %) patients were treated with oseltamivir/peramivir. 12 (16.9 %) patients suffered mortality. Non-survivors were more likely to have lower Glasgow coma score (median 7), longer duration of fever (median 3 days), with underlying medical conditions (P = 0.006), and complications including sepsis (P = 0.003), shock (P < 0.001), respiratory failure (P = 0.006), acute renal failure (P = 0.001), myocardial damage (P < 0.001), coagulation disorders (P = 0.03), electrolyte disturbance (P = 0.001) and hyperlactacidemia (P = 0.003). Non-survivors had higher percentages of corticosteroids (P = 0.003) and immunoglobulin (P = 0.003) treatments compared to survivors. CONCLUSIONS: Children with IAE have a high mortality rate. Lower Glasgow coma score, longer duration of fever, with underlying medical conditions and complications pose a great risk to poor prognosis. Influenza vaccination is recommended to all eligible children.

Antivirals for treatment of severe influenza: a systematic review and network meta-analysis of randomised controlled trials.

BACKGROUND: The optimal antiviral drug for treatment of severe influenza remains unclear. To support updated WHO influenza clinical guidelines, this systematic review and network meta-analysis evaluated antivirals for treatment of patients with severe influenza. METHODS: We systematically searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, Global Health, Epistemonikos, and ClinicalTrials.gov for randomised controlled trials published up to Sept 20, 2023, that enrolled hospitalised patients with suspected or laboratory-confirmed influenza and compared direct-acting influenza antivirals against placebo, standard care, or another antiviral. Pairs of coauthors independently extracted data on study characteristics, patient characteristics, antiviral characteristics, and outcomes, with discrepancies resolved by discussion or by a third coauthor. Key outcomes of interest were time to alleviation of symptoms, duration of hospitalisation, admission to intensive care unit, progression to invasive mechanical ventilation, duration of mechanical ventilation, mortality, hospital discharge destination, emergence of antiviral resistance, adverse events, adverse events related to treatments, and serious adverse events. We conducted frequentist network meta-analyses to summarise the evidence and evaluated the certainty of evidence using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. This study is registered with PROSPERO, CRD42023456650. FINDINGS: Of 11 878 records identified by our search, eight trials with 1424 participants (mean age 36-60 years for trials that reported mean or median age; 43-78% male patients) were included in this systematic review, of which six were included in the network meta-analysis. The effects of oseltamivir, peramivir, or zanamivir on mortality compared with placebo or standard care without placebo for seasonal and zoonotic influenza were of very low certainty. Compared with placebo or standard care, we found low certainty evidence that duration of hospitalisation for seasonal influenza was reduced with oseltamivir (mean difference -1·63 days, 95% CI -2·81 to -0·45) and peramivir (-1·73 days, -3·33 to -0·13). Compared with standard care, there was little or no difference in time to alleviation of symptoms with oseltamivir (0·34 days, -0·86 to 1·54; low certainty evidence) or peramivir (-0·05 days, -0·69 to 0·59; low certainty evidence). There were no differences in adverse events or serious adverse events with oseltamivir, peramivir, and zanamivir (very low certainty evidence). Uncertainty remains about the effects of antivirals on other outcomes for patients with severe influenza. Due to the small number of eligible trials, we could not test for publication bias. INTERPRETATION: In hospitalised patients with severe influenza, oseltamivir and peramivir might reduce duration of hospitalisation compared with standard care or placebo, although the certainty of evidence is low. The effects of all antivirals on mortality and other important patient outcomes are very uncertain due to scarce data from randomised controlled trials. FUNDING: World Health Organization.

Evaluating the Public Health and Health Economic Impacts of Baloxavir Marboxil and Oseltamivir for Influenza Pandemic Control in China: A Cost-Effectiveness Analysis Using a Linked Dynamic Transmission-Economic Evaluation Model.

BACKGROUND: Pandemic influenza poses a recurring threat to public health. Antiviral drugs are vital in combating influenza pandemics. Baloxavir marboxil (BXM) is a novel agent that provides clinical and public health benefits in influenza treatment. METHODS: We constructed a linked dynamic transmission-economic evaluation model combining a modified susceptible-exposed-infected-recovered (SEIR) model and a decision tree model to evaluate the cost-effectiveness of adding BXM to oseltamivir in China's influenza pandemic scenario. The cost-effectiveness was evaluated for the general population from the Chinese healthcare system perspective, although the users of BXM and oseltamivir were influenza-infected persons. The SEIR model simulated the transmission dynamics, dividing the population into four compartments: susceptible, exposed, infected, and recovered, while the decision tree model assessed disease severity and costs. We utilized data from clinical trials and observational studies in the literature to parameterize the models. Costs were based on 2021 CN¥ and not discounted due to a short time-frame of one year in the model. One-way, two-way, and probabilistic sensitivity analyses were also conducted. RESULTS: The integrated model demonstrated that adding BXM to treatment choices reduced the cumulative incidence of infection from 49.49% to 43.26% and increased quality-adjusted life years (QALYs) by 0.00021 per person compared with oseltamivir alone in the base-case scenario. The intervention also amounted to a positive net monetary benefit of CN¥77.85 per person at the willingness to pay of CN¥80,976 per QALY. Sensitivity analysis confirmed the robustness of these findings, with consistent results across varied key parameters and assumptions. CONCLUSIONS: Adding BXM to treatment choices instead of only treating with oseltamivir for influenza pandemic control in China appears to be cost-effective compared with oseltamivir alone. The dual-agent strategy not only enhances population health outcomes and conserves resources, but also mitigates influenza transmission and alleviates healthcare burden.

Factors Associated With Nonprescription of Oseltamivir for Infant Influenza Over 9 Seasons.

BACKGROUND: The Centers for Disease Control and Prevention (CDC) recommends oseltamivir phosphate for children <2 years old with confirmed or suspected influenza as they are at high risk for complications. We analyzed infant characteristics associated with nonprescription of oseltamivir over 9 years. METHODS: We conducted a retrospective electronic health record (EHR) review of infants <12 months old born between January 1, 2012 and December 31, 2019 within the University of Pittsburgh Medical Center health system in Southwestern Pennsylvania who had >2 well-child visits during their first year. Infants with a confirmed positive test for influenza were included in the analysis. Factors associated with infant oseltamivir nonprescription were assessed using multivariable logistic regression. RESULTS: Of 457 infants with confirmed influenza, 86% were prescribed oseltamivir. The proportion of infants prescribed oseltamivir increased from an average of 64.6% during the 2012-2016 influenza seasons to 90.4% during the 2016-2020 influenza seasons. Infants were more likely to not be prescribed oseltamivir if they experienced >2 days of influenza symptoms (odds ratio (OR): 9.4, 95% CI: 4.8, 18.7, P < .001), were diagnosed during the 2012-2016 influenza seasons (OR: 4.2, 95% CI: 1.8, 9.5, P < .001), tested positive for influenza via a multiplex/reverse transcriptase polymerase chain reaction test (OR: 6.7, 95% CI: 2.7, 16.3, P < .001; OR: 2.7, 95% CI: 1.1, 7.1; P = .04), or did not have a fever at point-of-care (OR: 2.3, 95% CI: 1.2, 4.6, P = .01). CONCLUSION: Adherence to CDC influenza antiviral treatment guidelines for infants is high and improved over time. However, the provision of targeted education to providers may further improve oseltamivir prescribing practices for high-risk children <12 months of age.

Influenza in Pregnancy: Maternal, Obstetric, and Fetal Implications, Diagnosis, and Management.

Influenza(flu) in pregnancy is associated with higher rates of hospitalization, ICU admission, and death and with increased odds of congenital anomalies and stillbirth, but not preterm birth. Clinical manifestations of flu in pregnancy are the same as nonpregnant patients. Pregnant individuals with flu-like symptoms or flu exposure should be treated with antivirals. Diagnostic testing is not needed. Oseltamivir is the mainstay of treatment(and prophylaxis), and when given within 48 hours of symptom onset, it decreases morbidity and mortality. Influenza is associated with worse maternal, obstetric, and neonatal outcomes. These risks are mitigated by early oseltamivir treatment and maternal vaccination; hence the recommendation for universal vaccination in pregnancy.

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.

Duration of fever in children infected with influenza A(H1N1)pdm09, A(H3N2) or B virus and treated with baloxavir marboxil, oseltamivir, laninamivir, or zanamivir in Japan during the 2012-2013 and 2019-2020 influenza seasons.

We compared the duration of fever in children infected with A(H1N1)pdm09, A(H3N2), or influenza B viruses following treatment with baloxavir marboxil (baloxavir) or neuraminidase inhibitors (NAIs) (oseltamivir, zanamivir, or laninamivir). This observational study was conducted at 10 outpatient clinics across 9 prefectures in Japan during the 2012-2013 and 2019-2020 influenza seasons. Patients with influenza rapid antigen test positive were treated with one of four anti-influenza drugs. The type/subtype of influenza viruses were identified from MDCK or MDCK SIAT1 cell-grown samples using two-step real-time PCR. Daily self-reported body temperature after treatment were used to evaluate the duration of fever by treatment group and various underlying factors. Among 1742 patients <19 years old analyzed, 452 (26.0%) were A(H1N1)pdm09, 827 (48.0%) A(H3N2), and 463 (26.0%) influenza B virus infections. Among fours treatment groups, baloxavir showed a shorter median duration of fever compared to oseltamivir in univariate analysis for A(H1N1)pdm09 virus infections (baloxavir, 22.0 h versus oseltamivir, 26.7 h, P < 0.05; laninamivir, 25.5 h, and zanamivir, 25.0 h). However, this difference was not significant in multivariable analyses. For A(H3N2) virus infections, there were no statistically significant differences observed (20.3, 21.0, 22.0, and 19.0 h) uni- and multivariable analyses. For influenza B, baloxavir shortened the fever duration by approximately 15 h than NAIs (20.3, 35.0, 34.3, and 34.1 h), as supported by uni- and multivariable analyses. Baloxavir seems to have comparable clinical effectiveness with NAIs on influenza A but can be more effective for treating pediatric influenza B virus infections than NAIs.

Multicountry Spread of Influenza A(H1N1)pdm09 Viruses with Reduced Oseltamivir Inhibition, May 2023-February 2024.

Since May 2023, a novel combination of neuraminidase mutations, I223V + S247N, has been detected in influenza A(H1N1)pdm09 viruses collected in countries spanning 5 continents, mostly in Europe (67/101). The viruses belong to 2 phylogenetically distinct groups and display ≈13-fold reduced inhibition by oseltamivir while retaining normal susceptibility to other antiviral drugs.

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

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

Bird Flu Outbreak in Dairy Cows Is Widespread, Raising Public Health Concerns.

This Medical News article discusses the current H5N1 avian influenza outbreak in US dairy cattle and its implications for occupational and public health.

Comparative Effectiveness of Baloxavir Marboxil and Oseltamivir Treatment in Reducing Household Transmission of Influenza: A Post Hoc Analysis of the BLOCKSTONE Trial.

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.

Pharmacoeconomic study of anti-influenza virus drugs in Japan based on a network meta-analysis.

BACKGROUND: An analysis was conducted in Japan to determine the most cost-effective neuraminidase inhibitor for the treatment of influenza virus infections from the healthcare payer's standpoint. OBJECTIVE: This study reanalysed the findings of a previous study that had some limitations (no probabilistic sensitivity analysis and quality of life scores measured by the EQ-5D-3L instead of the EQ-5D-5L) and used a decision tree model with only three health conditions. METHODS: This study incorporated new data from a network meta-analysis study into the first examination. The second examination involved constructing a new decision tree model encompassing seven health conditions and identifying costs, which consisted of medical costs and drug prices based on the 2020 version of the Japanese medical fee index. Effectiveness outcomes were measured using EQ-5D-5L questionnaires for adult patients with a history of influenza virus infections within a 14-day time horizon. Deterministic and probabilistic sensitivity analyses were performed to examine the uncertainty. RESULTS: In the first examination, the base-case cost-effectiveness analysis confirmed that oseltamivir outperformed laninamivir, zanamivir and peramivir, making it the most cost-effective neuraminidase inhibitor. The second examination revealed that oseltamivir dominated the other agents. Both deterministic and probabilistic sensitivity analyses showed robust results that validated oseltamivir as the most cost effective among the four neuraminidase inhibitors. CONCLUSIONS: This study thus reaffirms oseltamivir's position as the most cost-effective neuraminidase inhibitor for the treatment of influenza virus infections in Japan from the perspective of healthcare payment. These findings can help decision makers and healthcare providers in Japan.

In Vivo Immune-Modulatory Activity of Lefamulin in an Influenza Virus A (H1N1) Infection Model in Mice.

Lefamulin is a first-in-class systemic pleuromutilin antimicrobial and potent inhibitor of bacterial translation, and the most recent novel antimicrobial approved for the treatment of community-acquired pneumonia (CAP). It exhibits potent antibacterial activity against the most prevalent bacterial pathogens that cause typical and atypical pneumonia and other infectious diseases. Early studies indicate additional anti-inflammatory activity. In this study, we further investigated the immune-modulatory activity of lefamulin in the influenza A/H1N1 acute respiratory distress syndrome (ARDS) model in BALB/c mice. Comparators included azithromycin, an anti-inflammatory antimicrobial, and the antiviral oseltamivir. Lefamulin significantly decreased the total immune cell infiltration, specifically the neutrophils, inflammatory monocytes, CD4+ and CD8+ T-cells, NK cells, and B-cells into the lung by Day 6 at both doses tested compared to the untreated vehicle control group (placebo), whereas azithromycin and oseltamivir did not significantly affect the total immune cell counts at the tested dosing regimens. Bronchioalveolar lavage fluid concentrations of pro-inflammatory cytokines and chemokines including TNF-α, IL-6, IL-12p70, IL-17A, IFN-γ, and GM-CSF were significantly reduced, and MCP-1 concentrations were lowered (not significantly) by lefamulin at the clinically relevant 'low' dose on Day 3 when the viral load peaked. Similar effects were also observed for oseltamivir and azithromycin. Lefamulin also decreased the viral load (TCID50) by half a log10 by Day 6 and showed positive effects on the gross lung pathology and survival. Oseltamivir and lefamulin were efficacious in the suppression of the development of influenza-induced bronchi-interstitial pneumonia, whereas azithromycin did not show reduced pathology at the tested treatment regimen. The observed anti-inflammatory and immune-modulatory activity of lefamulin at the tested treatment regimens highlights a promising secondary pharmacological property of lefamulin. While these results require confirmation in a clinical trial, they indicate that lefamulin may provide an immune-modulatory activity beyond its proven potent antibacterial activity. This additional activity may benefit CAP patients and potentially prevent acute lung injury (ALI) and ARDS.