Influenza infection in immunosuppressed patients: clinical characteristics, risk factors and effect of antiviral therapy

Abstract Background: Influenza infection was a vital threat to immunosuppressed patients with longer viral shedding; however, data on these populations in China are still lacking. We analyzed clinical characteristics, risk factors for admission to intensive care unit (ICU) and death, and effect of antiviral therapy in these populations.Methods: We analyzed 73 immunosuppressed inpatients tested positive for influenza virus using reverse-transcription polymerase chain reaction during the 2018-2019 influenza season. Medical data were analyzed using descriptive statistics. Univariate analysis and multivariate logistics analysis were used to identify risk factors. Results: The most common immunosuppression type was malignancies with chemotherapy 73.9% (54/73), then hematopoietic stem cell transplantation 19.2% (14/73). The most common presenting symptom was fever in 91.8% (67/73) patients, then cough 59.6% (34/57) and muscular soreness 35.1% (20/57). Complications and co-infections were found in 38.4% (28/73) and 17.8% (13/73) patients respectively, which significantly prolonged the hospital stay. Antiviral treatment after 48 hours was significantly associated with admission to ICU, mechanical ventilation and death. Combination and double dose of neuraminidase inhibitors did not significantly reduce the admission to ICU and death. 15.1% (11/73) patients were admitted to ICU and 8.2% (6/73) patients died. Risk factors for admission to ICU were long symptom onset (OR 5.60, P=0.018) and co-infection with other infections (OR 68.66, P=0.019), and presence of dyspnea was independently associated with death (OR 48.00, P=0.003) through multivariate logistics analysis. Seasonal influenza vaccination in preceding 12 months only took up 2.7% (2/73).Conclusion: Fever and other classical symptoms may be absent in immunosuppressed recipients, and conducting influenza virus detection at the first time is a good choice for early diagnosis. Antiviral treatment within 48 hours is of significance; however, patients may not benefit from combination and double dose of neuraminidase inhibitors. Immunosuppressed patients with dyspnea, long symptom onset and co-infection with other infections are of note needed, because these people have high-risk to severe cases. Inactivated influenza vaccination should be taken into account in immunosuppressed patients.

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Clinical Characteristics, Risk Factors and Antiviral Treatments of Influenza in Immunosuppressed Inpatients in Beijing During the 2015-2020 Influenza Seasons

10.21203/rs.3.rs-910455/v1 ◽

2021 ◽

Author(s):

Yafen Liu ◽

Yue Wang ◽

Huan Mai ◽

YuanYuan Chen ◽

Baiyi Liu ◽

...

Keyword(s):

Risk Factors ◽

Influenza Virus ◽

Influenza Vaccination ◽

Mental Status ◽

Clinical Characteristics ◽

Antiviral Treatment ◽

Univariate Analysis ◽

Altered Mental Status ◽

Hematopoietic Stem ◽

Immunosuppressed Patients

Abstract Background Influenza infection was a vital threat to immunosuppressed patients with longer viral shedding; however, data on these populations in China are still lacking. We analyzed clinical characteristics, risk factors and effects of antiviral therapy in these populations. Methods We analyzed 111 immunosuppressed inpatients tested positive for influenza virus using RT-PCR during the 2015–2020 influenza seasons. Univariate analysis and multivariate logistics analysis were used to identify risk factors. Results The most common immunosuppression type was malignancies with chemotherapy 87.4% (97/111), then hematopoietic stem cell transplantation 23.4% (26/111). The most common presenting symptom was fever in 92.8% (103/111) patients, then cough 50.6% (44/87). 14.4% (16/111) patients were admitted to ICU and 9.9% (11/111) patients died. Combination and double dose of neuraminidase inhibitors did not significantly reduce the admission to ICU and death. Risk factors for admission to ICU were dyspnea, co-infection with other infections and no antiviral treatment within 48 hours, and presence of dyspnea and altered mental status were independently associated with death through multivariate logistics analysis. Seasonal influenza vaccination in preceding 12 months only took up 2.7% (3/111). Conclusion Fever and other classical symptoms of influenza may be absent in immunosuppressed recipients, and conducting influenza virus detection at the first time is a good choice for early diagnosis. Immunosuppressed patients with dyspnea, altered mental status, co-infection with other infections and no antiviral treatment within 48 hours are of note needed, because these people have high-risk to severe cases. Inactivated influenza vaccination should be taken into account in immunosuppressed patients.

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Clinical characteristics, risk factors and antiviral treatments of influenza in immunosuppressed inpatients in Beijing during the 2015–2020 influenza seasons

Virology Journal ◽

10.1186/s12985-021-01739-1 ◽

2022 ◽

Vol 19 (1) ◽

Author(s):

Yafen Liu ◽

Yue Wang ◽

Huan Mai ◽

YuanYuan Chen ◽

Baiyi Liu ◽

...

Keyword(s):

Risk Factors ◽

Influenza Virus ◽

Mental Status ◽

Clinical Characteristics ◽

Antiviral Treatment ◽

Altered Mental Status ◽

Haematopoietic Stem Cell ◽

Severe Illness ◽

Presenting Symptoms ◽

Immunosuppressed Patients

Abstract Background Compared with immunocompetent patients, immunosuppressed patients have higher morbidity and mortality, a longer duration of viral shedding, more frequent complications, and more antiviral resistance during influenza infections. However, few data on this population in China have been reported. We analysed the clinical characteristics, effects of antiviral therapy, and risk factors for admission to the intensive care unit (ICU) and death in this population after influenza infections and explored the influenza vaccination situation for this population. Methods We analysed 111 immunosuppressed inpatients who were infected with influenza virus during the 2015–2020 influenza seasons. Medical data were collected through the electronic medical record system and analysed. Univariate analysis and multivariate logistics analysis were used to identify risk factors. Results The most common cause of immunosuppression was malignancies being treated with chemotherapy (64.0%, 71/111), followed by haematopoietic stem cell transplantation (HSCT) (23.4%, 26/111). The most common presenting symptoms were fever and cough. Dyspnoea, gastrointestinal symptoms and altered mental status were more common in HSCT patients than in patients with immunosuppression due to other causes. Approximately 14.4% (16/111) of patients were admitted to the ICU, and 9.9% (11/111) of patients died. Combined and double doses of neuraminidase inhibitors did not significantly reduce the risk of admission to the ICU or death. Risk factors for admission to the ICU were dyspnoea, coinfection with other pathogens and no antiviral treatment within 48 h. The presence of dyspnoea and altered mental status were independently associated with death. Only 2.7% (3/111) of patients less than 12 months old had received a seasonal influenza vaccine. Conclusion Fever and other classic symptoms of influenza may be absent in immunosuppressed recipients, especially in HSCT patients. Conducting influenza virus detection at the first presentation seems to be a good choice for early diagnosis. Clinicians should pay extra attention to immunosuppressed patients with dyspnoea, altered mental status, coinfection with other pathogens and no antiviral treatment within 48 h because these patients have a high risk of severe illness. Inactivated influenza vaccines are recommended for immunosuppressed patients.

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Clinical characteristics, evolution, and treatment-related risk factors for mortality among immunosuppressed patients with influenza A (H1N1) virus admitted to the intensive care unit

Journal of Critical Care ◽

10.1016/j.jcrc.2018.08.017 ◽

2018 ◽

Vol 48 ◽

pp. 172-177 ◽

Cited By ~ 8

Author(s):

José Garnacho-Montero ◽

Cristina León-Moya ◽

Antonio Gutiérrez-Pizarraya ◽

Angel Arenzana-Seisdedos ◽

Loreto Vidaur ◽

...

Keyword(s):

Risk Factors ◽

Intensive Care Unit ◽

Intensive Care ◽

Influenza A ◽

Clinical Characteristics ◽

H1n1 Virus ◽

Related Risk ◽

Influenza A H1n1 ◽

Immunosuppressed Patients

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Hospitalized Adult Patients with 2009 Pandemic Influenza A (H1N1) in Kaunas, Lithuania

Medicina ◽

10.3390/medicina47010002 ◽

2011 ◽

Vol 47 (1) ◽

pp. 11-18 ◽

Cited By ~ 4

Author(s):

◽

...

Keyword(s):

Risk Factors ◽

Symptom Onset ◽

Pandemic Influenza ◽

Influenza A ◽

H1n1 Virus ◽

Clinical Course ◽

Antiviral Treatment ◽

Course Of Illness ◽

Influenza A H1n1 ◽

Complicated Course

The objective of this study was to identify case characteristics and clinical course of the disease in patients hospitalized with 2009 pandemic influenza A (H1N1) infection during the first wave of the pandemic and to identify risk factors associated with the complicated course of illness. Material and methods. A retrospective study of adult cases of the laboratory-confirmed 2009 pandemic influenza A (H1N1) virus admitted to three hospitals in Kaunas between November 1, 2009, and March 15, 2010, was carried out. The main outcome measures were clinical characteristics, risk factors for complicated disease, treatment, and clinical course of the disease. Results. The study enrolled 121 of the 125 patients hospitalized due to 2009 pandemic influenza A (H1N1) virus infection. The median age was 31 years (range, 18–83); 5% of the patients were aged more than 65 years. Pregnant and postpartum women comprised 26% of all hospitalized cases. Nearly half (49.5%) of those who underwent chest radiography had findings consistent with pneumonia, which was bilateral in one-third of cases. The risk to have pandemic influenza complicated by pneumonia increased significantly with one-day delay from symptom onset to antiviral treatment (OR, 2.241; 95% CI, 1.354–3.710). More than half (57%) of the patients received antiviral treatment. In 45% of the treated patients, antiviral drugs were administered within 48 hours from symptom onset. Intensive care was required in 7.4% of the cases. The overall mortality was 5% (6/121). The median age of the patients who died was 43.5 years (range, 23–62); 4 patients had been previously healthy, 1 patient suffered from chronic lympholeukemia, and 1 patient was a pregnant woman. Conclusion. The 2009 pandemic influenza A (H1N1) caused considerable morbidity in a significant proportion of hospitalized adults. The main risk factor associated with the complicated course of illness was delayed antiviral treatment.

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Clinical characteristics of progressive nonarteritic anterior ischemic optic neuropathy

International Journal of Ophthalmology ◽

10.18240/ijo.2021.04.06 ◽

2021 ◽

Vol 14 (4) ◽

pp. 517-522

Author(s):

Omer Y. Bialer ◽

Keyword(s):

Risk Factors ◽

Visual Acuity ◽

Color Vision ◽

Symptom Onset ◽

Systemic Risk ◽

Clinical Characteristics ◽

Visual Outcome ◽

Ischemic Optic Neuropathy ◽

Systemic Risk Factors

AIM: To study whether patients with progressive nonarteritic anterior ischemic optic neuropathy (NAION) present earlier than patients with stable NAION and to describe their clinical characteristics and visual outcome. METHODS: This was a retrospective chart review. All patients with NAION seen during the acute stage from January 2012 to December 2018 were reviewed. Patients were included if they had documented disc edema and follow up of at least 3mo. Patients with progressive NAION were identified if they worsened in 2 out of 3 parameters: visual acuity ≥3 Snellen lines; Color vision ≥4 Ishihara plates; the visual field defect involved a new quadrant. The clinical characteristics, time from symptom onset to presentation, systemic risk factors and visual outcome were compared to patients with stable NAION. RESULTS: Totally 122 NAION cases met the inclusion criteria. Mean age was 58.1y (range 22-74), 70% were men. Twenty cases (16.4%) had progressive NAION. Patients with progressive NAION did not differ from stable NAION in their demographics, systemic risk factors or in their initial visual deficit. At last follow up, median visual acuity was 1.0 logMAR (IQR 0.64-1.55) in patients with progressive NAION, vs 0.18 (IQR 0.1-0.63) in stable NAION (P&#x003C;0.001). Median color vision testing was 0 plates correct (IQR 0-2.5%) vs 92% plates correct (IQR 50%-100%) in the stable NAION group (P&#x003C;0.001). Patients with progressive NAION differed in the time from symptom onset to presentation (median 2d vs 5d, P=0.011). CONCLUSION: We find no identifiable risk factors associated with progressive NAION. Progressors arrive earlier for ophthalmological evaluation.

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Factors associated with prolonged viral shedding and impact of lopinavir/ritonavir treatment in hospitalised non-critically ill patients with SARS-CoV-2 infection

European Respiratory Journal ◽

10.1183/13993003.00799-2020 ◽

2020 ◽

Vol 56 (1) ◽

pp. 2000799 ◽

Cited By ~ 36

Author(s):

Dan Yan ◽

Xiao-Yan Liu ◽

Ya-nan Zhu ◽

Li Huang ◽

Bi-tang Dan ◽

...

Keyword(s):

Risk Factors ◽

Symptom Onset ◽

Antiviral Treatment ◽

Older Age ◽

Rna Detection ◽

Factors Associated ◽

Viral Shedding ◽

Reverse Transcription Pcr ◽

Independent Risk Factors ◽

The Impact

BackgroundThe duration of viral shedding is central to the guidance of decisions about isolation precautions and antiviral treatment. However, studies regarding the risk factors associated with prolonged shedding of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the impact of lopinavir/ritonavir (LPV/r) treatment on viral shedding remain scarce.MethodsData were collected from all SARS-CoV-2 infected patients who were admitted to isolation wards and had reverse transcription PCR conversion at the No. 3 People's Hospital of Hubei province, China, between 31 January and 9 March 2020. We compared clinical characteristics and SARS-CoV-2 RNA shedding between patients initiated with LPV/r treatment and those without. Logistic regression analysis was employed to evaluate the risk factors associated with prolonged viral shedding.ResultsOf 120 patients, the median age was 52 years, 54 (45%) were male and 78 (65%) received LPV/r treatment. The median duration of SARS-CoV-2 RNA detection from symptom onset was 23 days (interquartile range 18–32 days). Older age (OR 1.03, 95% CI 1.00–1.05; p=0.03) and the lack of LPV/r treatment (OR 2.42, 95% CI 1.10–5.36; p=0.029) were independent risk factors for prolonged SARS-CoV-2 RNA shedding. Patients who initiated LPV/r treatment within 10 days from symptom onset, but not initiated from day 11 onwards, had significantly shorter viral shedding duration compared with those without LPV/r treatment (median 19 days versus 28.5 days; log-rank p<0.001).ConclusionOlder age and the lack of LPV/r treatment were independently associated with prolonged SARS-CoV-2 RNA shedding in patients with coronavirus disease 2019 (COVID-19). Earlier administration of LPV/r treatment could shorten viral shedding duration.

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Time and dose-dependent risk of pneumococcal pneumonia following influenza: a model for within-host interaction between influenza and Streptococcus pneumoniae

Journal of The Royal Society Interface ◽

10.1098/rsif.2013.0233 ◽

2013 ◽

Vol 10 (86) ◽

pp. 20130233 ◽

Cited By ~ 26

Author(s):

Sourya Shrestha ◽

Betsy Foxman ◽

Suzanne Dawid ◽

Allison E. Aiello ◽

Brian M. Davis ◽

...

Keyword(s):

Influenza Virus ◽

Streptococcus Pneumoniae ◽

Animal Models ◽

Pneumococcal Disease ◽

Influenza Infection ◽

Clinical Care ◽

Antiviral Treatment ◽

Inoculum Size ◽

Immune Mediated ◽

Quantitative Understanding

A significant fraction of seasonal and in particular pandemic influenza deaths are attributed to secondary bacterial infections. In animal models, influenza virus predisposes hosts to severe infection with both Streptococcus pneumoniae and Staphylococcus aureus . Despite its importance, the mechanistic nature of the interaction between influenza and pneumococci, its dependence on the timing and sequence of infections as well as the clinical and epidemiological consequences remain unclear. We explore an immune-mediated model of the viral–bacterial interaction that quantifies the timing and the intensity of the interaction. Taking advantage of the wealth of knowledge gained from animal models, and the quantitative understanding of the kinetics of pathogen-specific immunological dynamics, we formulate a mathematical model for immune-mediated interaction between influenza virus and S. pneumoniae in the lungs. We use the model to examine the pathogenic effect of inoculum size and timing of pneumococcal invasion relative to influenza infection, as well as the efficacy of antivirals in preventing severe pneumococcal disease. We find that our model is able to capture the key features of the interaction observed in animal experiments. The model predicts that introduction of pneumococcal bacteria during a 4–6 day window following influenza infection results in invasive pneumonia at significantly lower inoculum size than in hosts not infected with influenza. Furthermore, we find that antiviral treatment administered later than 4 days after influenza infection was not able to prevent invasive pneumococcal disease. This work provides a quantitative framework to study interactions between influenza and pneumococci and has the potential to accurately quantify the interactions. Such quantitative understanding can form a basis for effective clinical care, public health policies and pandemic preparedness.

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Clinical and immunological changes in patients with chronic inflammatory diseases of the upper respiratory tract at different periods after administration of influenza vaccine. Message 1. The influence of parenteral influenza vaccination on the clinical condition and indicators of systemic humoral immunity in patients with chronic inflammatory diseases of the upper respiratory tract

OTORHINOLARYNGOLOGY 2-3(2) 2019 - OTORHINOLARYNGOLOGY ◽

10.37219/2528-8253-2021-5-04 ◽

2021 ◽

pp. 4-11

Author(s):

Dmitry I. Zabolotny ◽

Oleg F. Melnikov ◽

Sergei V. Timchenko ◽

Oksana G. Rylska ◽

Inna V. Faraon ◽

...

Keyword(s):

Influenza Virus ◽

Respiratory Tract ◽

Influenza Vaccination ◽

Clinical Condition ◽

Inflammatory Diseases ◽

Influenza Infection ◽

Upper Respiratory Tract ◽

Total Ige ◽

Chronic Inflammatory Diseases ◽

Upper Respiratory

Topicality: Today, as an assessment of the effectiveness of vaccination against influenza infection is to determine the level of antibodies against influenza virus hemagglutinin, which is determined by the reaction of inhibition of hemagglutination. It is known that the effect of vaccination with modern drugs is short-lived, compared with what remains after the disease. Therefore, there is a need for further vaccinations, which are carried out without taking into account the state of immunity in those who will be vaccinated. This raises the question of the appropriateness of this approach in individuals who, according to this indicator, can already be considered protected from influenza infection and how often such patients occur in clinical practice. Material and methods: From the autumn-winter period of 2019 to November 2020, 32 donors and 32 patients with chronic inflammatory diseases of the upper respiratory tract chronic inflammatory diseases of the upper respiratory tract of both sexes who were not vaccinated for 1 year before the study were examined. Among these patients, 11 were diagnosed with chronic rhinosinusitis, 9 with chronic tonsillitis, and 12 with chronic pharyngitis. All patients with chronic inflammatory diseases of the upper respiratory tract underwent a complete otolaryngological examination prior to influenza vaccination and were monitored for another 36 weeks thereafter. Attention was paid to their general clinical condition, cases of exacerbations of chronic inflammatory diseases of the upper respiratory tract and the number of episodes of acute respiratory viral infections during the year before vaccination according to the anamnesis and for the observation period during the post-vaccination period. Samples of serum venous blood of donors, as well as persons with chronic inflammatory diseases of the upper respiratory tract were obtained at the initial examination, and in vaccinated patients 3, 12 and 36 weeks after vaccination and stored at -20°C (Ardo, Italy) until the simultaneous detection of antibodies (Ab) to influenza A and B viruses by hemagglutination inhibition reaction with human erythrocytes 0 group. Trivalent influenza inactivated split vaccine Vaxigrip (France) was used both for vaccination and in the determination of Ab in the blood for influenza viruses. In all examinations, the titer of anti-influenza Ab and the content of immune complexes were determined in the sera of patients, and the content of total IgE was measured in patients with chronic inflammatory diseases of the upper respiratory tract before and after 12 and 36 weeks. Statistical processing of the obtained results was performed in accordance with the recommendations of Glantz. Results: In 41% of those examined protectively significant titers of antibodies to hemagglutinins of vaccine strains of influenza virus vaccine Vaxigrip were detected in the blood. Parenteral vaccination of patients with chronic inflammatory diseases of the upper respiratory tract against influenza helped to improve the course of their underlying clinical disease and reduce their incidence of acute respiratory viral infections within 36 weeks after vaccination. The effect of increasing the level of antibodies to hemagglutinins of influenza virus remained at the limit of 3 months and decreased. Influenza vaccination in patients with chronic inflammatory diseases of the upper respiratory tract with the presence of most of them at the time of vaccination of clinically significant protective titers of antibodies to hemagglutinins vaccine strains of viruses led to an increase in blood in the long term of the vaccination process levels of immune complex and total IgE relative to their initial level, while these indicators did not exceed the limits of their physiological values. Conclusion: Single parenteral influenza vaccination leads to a short-term increase in the blood of specific projective antibodies, improving the clinical condition of patients with inflammatory diseases of the upper respiratory tract, increasing the level of immune complexes and total IgE.

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Infectious virus in exhaled breath of symptomatic seasonal influenza cases from a college community

10.1101/194985 ◽

2017 ◽

Author(s):

Jing Yan ◽

Michael Grantham ◽

Jovan Pantelic ◽

P. Jacob Bueno de Mesquita ◽

Barbara Albert ◽

...

Keyword(s):

Influenza Virus ◽

Symptom Onset ◽

Infectious Virus ◽

Influenza Infection ◽

Geometric Mean ◽

Viral Rna ◽

Exhaled Breath ◽

Negatively Associated ◽

Aerosol Generation ◽

Coarse Aerosol

AbstractLittle is known about the amount and infectiousness of influenza virus shed into exhaled breath. This contributes to uncertainty about the importance of airborne influenza transmission. We screened 355 symptomatic volunteers with acute respiratory illness and report 142 cases with confirmed influenza infection who provided 218 paired nasopharyngeal (NP) and 30-minute breath samples (coarse >5 μm and fine <5 μm fractions) on days 1 to 3 post symptom onset. We assessed viral RNA copy number for all samples and cultured NP swabs and fine aerosols. We recovered infectious virus from 52 (39%) of the fine aerosols and 150 (89%) of the NP swabs with valid cultures. The geometric mean RNA copy numbers were 3.8×104/30-min fine, 1.2×104/30-min coarse aerosol sample, and 8.2×108 per NP swab. Fine and coarse aerosol viral RNA was positively associated with body mass index (fine p<0.05, coarse p<0.10) and number of coughs (fine p<0.001, coarse p<0.01) and negatively associated with increasing days since symptom onset (fine p<0.05 to p<0.01, coarse p<0.10) in adjusted models. Fine aerosol viral RNA was also positively associated with having influenza vaccination for both the current and prior season (p<0.01). NP swab viral RNA was positively associated with upper respiratory symptoms (p<0.01) and negatively associated with age (p<0.01) but was not significantly associated with fine or coarse aerosol viral RNA or their predictors. Sneezing was rare, and sneezing and coughing were not necessary for infectious aerosol generation. Our observations suggest that influenza infection in the upper and lower airways are compartmentalized and independent.SignificanceLack of human data on influenza virus aerosol shedding fuels debate over the importance of airborne transmission. We provide overwhelming evidence that humans generate infectious aerosols and quantitative data to improve mathematical models of transmission and public health interventions. We show that sneezing is rare and not important for, and that coughing is not required for influenza virus aerosolization. Our findings, that upper and lower airway infection are independent and that fine particle exhaled aerosols reflect infection in the lung, open a new pathway for understanding the human biology of influenza infection and transmission. Our observation of an association between repeated vaccination and increased viral aerosol generation demonstrated the power of our method, but needs confirmation.

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1712. Epidemiology, Clinical Characteristics, and Outcomes of Influenza-Associated Hospitalizations in Children in the post-2009 Pandemic Era

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1890 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S839-S840

Author(s):

Satoshi Kamidani ◽

Shikha Garg ◽

Angela P Campbell ◽

Charisse N Cummings ◽

Kyle P Openo ◽

...

Keyword(s):

Mechanical Ventilation ◽

Influenza Vaccination ◽

Vaccination Coverage ◽

Clinical Characteristics ◽

Vaccine Coverage ◽

Influenza Pandemic ◽

Antiviral Treatment ◽

Research Support ◽

Standard Case ◽

Hospitalization Rates

Abstract Background Significant changes in influenza vaccination coverage and antiviral treatment guidance occurred following the 2009 influenza pandemic in children. However, data are limited describing recent epidemiology, clinical characteristics, antiviral use, vaccine coverage, and outcomes of influenza-related hospitalizations in children. Methods Children < 18 years hospitalized with influenza during seasons 2010–2011 through 2018–2019 were included through the US Influenza Hospitalization Surveillance Network (FluSurv-NET). Age-stratified hospitalization rates were calculated using the number of catchment-area residents with laboratory-confirmed influenza within 14 days prior to or ≤3 days after hospital admission during October 1-April 30 of each influenza season. Data on underlying medical history, influenza vaccination, antiviral use, and outcomes were abstracted from medical records using standard case report forms by trained surveillance officers. Results Over 9 seasons, 13,235 children were identified. Stepwise decreases in unadjusted hospitalization rates with age occurred, with the highest rates in infants < 6 months (ranging 56–184 per 100,000 persons) (Fig.1). Among these children, 56% were male, 34% were non-Hispanic White, 55% had a preexisting medical condition, and 8% were immunocompromised (Table 1). Use of antiviral treatment substantially increased from 56% to 85%, and influenza vaccination rates among hospitalized children increased from 34% to 43% over time. Regarding severe outcomes, 2,676 (20%) were admitted to ICU, 2,262 (17%) had pneumonia, 690 (5%) required mechanical ventilation, and 72 (0.5%) died. In univariable analysis, compared to hospitalized infants < 6 months, children >13 years had higher odds of ICU admission (odds ratio (OR), 2.0; 95% CI, 1.7–2.4), mechanical ventilation (OR, 1.7; 95% CI, 1.2–2.3), and pneumonia (OR, 2.6; 95% CI, 2.1–3.3) (Table 2). Figure 1 Table 1 Table 2 Conclusion Although influenza-related hospitalization rates decreased with increasing age, severe outcomes were more common among hospitalized older children. Room for improvement exists in influenza vaccination coverage and antiviral use. While 20% of children were admitted to ICU, death was uncommon. Disclosures Sue Kim, MPH, Council of State and Territorial Epidemiologists (CSTE) (Grant/Research Support) Melissa Sutton, MD, MPH, CDC funding (Emerging Infections Program) (Grant/Research Support) Evan J. Anderson, MD, Sanofi Pasteur (Scientific Research Study Investigator)

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