Influenza Complications Research Articles

Influenza epidemiology in patients admitted to sentinel Australian hospitals in 2019: the Influenza Complications Alert Network (FluCAN).

Influenza is a common cause of acute respiratory infection, and is a major cause of morbidity and mortality. This report summarises the epidemiology of hospitalisations with laboratory-confirmed influenza during the 2019 influenza season. The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance program that operates at sites in all jurisdictions in Australia. Cases were defined as patients hospitalised at any of the 17 sentinel hospitals with influenza confirmed by nucleic acid detection. Data were also collected on a frequency matched control group of influenza-negative patients admitted with acute respiratory infection. During the period 1 April to 31 October 2019 (the 2019 influenza season), there were 4,154 patients admitted with confirmed influenza to one of 17 FluCAN sentinel hospitals. Of these, 44% were elderly (≥ 65 years), 21% were children (< 16 years), 7.7% were Aboriginal and Torres Strait Islander peoples, 1.7% were pregnant and 73% had chronic comorbidities. Most admissions were due to influenza A infection (85%). Estimated vaccine coverage was 75% in the elderly, 49% in non-elderly adults with medical comorbidities, and 27% in young children (< 5 years). The estimated vaccine effectiveness in the target adult population was 42% (95% confidence interval [95% CI]: 36%, 49%). There were a larger number of hospital admissions detected with confirmed influenza in this national observational surveillance system in 2019 than in 2018.

Clinical manifestations of hospitalized influenza patients without risk factors: A prospective multicenter cohort study in Japan via internet surveillance

IntroductionInfluenza remains a clinically heavy burden worldwide. It is well known that some populations are at high risk of complications from influenza, whereas, even previously healthy people might suffer from severe influenza.The objective of this study was to clarify clinical manifestations of hospitalized patients without risk factors infected with influenza. MethodsThe clinical data for patients who were severely ill with influenza, and required hospitalization were gathered and analyzed between November 2014 and August 2020 (6 influenza seasons) using an internet-surveillance system. Among them, the patients who had no risk factors of complications from influenza were extracted. ResultsFinally, a total of 91 patients (9.0% of all influenza-related hospitalizations) without risk factors were analyzed. The no risk group was younger than the risk group, though other significant differences of clinical characteristics were not recognized between the groups. Pneumonia was the most common cause of hospitalization in the no risk group, and primary influenza viral pneumonia was the most common pneumonia. Antiviral drugs were administered in 96.7% of the no-risk group, and artificial ventilation was performed in 18.7%. In-hospital death was recorded for 3 patients without risk factors. ConclusionsSevere complications of influenza which required hospitalization may occur in a certain degree of patients with no risk factors. Efforts are needed to diagnose and treat influenza appropriately even in previously healthy younger patients. Continuous nationwide surveillance will be required to clarify risk factors for severe influenza even in previously healthy younger patients.(UMIN000015989).

Identification of Barriers Limiting the Use of Preventive Vaccinations against Influenza among the Elderly Population: A Cross-Sectional Analysis.

Older adults are at a high risk of experiencing severe complications of influenza. Receiving a vaccination is a beneficial strategy to prevent the disease and reduce the severity of influenza illnesses. This cross-sectional questionnaire-based study aimed to evaluate the influence of sociodemographic, clinical, and mental parameters as well as other potential risk factors on refusal to vaccinate against influenza among the elderly population in Poland. Furthermore, due to the prevailing COVID-19 pandemic, we put efforts into finding any statistical correlations between the fear of COVID-19 infection in patients and their attitudes toward receiving an influenza vaccination. The study was conducted in November–December 2020 in Poland on a representative nationwide sample of 500 individuals aged > 60. Of the respondents, 62 (12.4%) and 51 (10.2%) underwent influenza vaccination in 2019 and 2020, respectively. Out of ten different factors analyzed in this study, three were significantly associated with attitudes towards influenza vaccination. Participants with net income below the national average of PLN 3000 (OR = 2.37, CI 95% [1.26–4.47]), compared to those earning more than PLN 3000, had significantly higher odds of having a negative attitude towards influenza vaccination. Furthermore, respondents with <174 cm height (OR = 2.56, CI 95% [1.51–4.33]) and those with strong fear of COVID-19 infection (OR = 1.65, CI95% [1.02–2.66]) were also more likely to refrain from influenza vaccination. We believe the identification of factors limiting the willingness to receive influenza vaccination is an effective way to help clinicians focus their efforts on educating the groups of patients with the highest odds of refusing to receive the vaccine. Moreover, it may aid the design and enforcement of national solutions or the implementation of novel legislative measures and preventive programs, increasing public confidence and promoting vaccination, especially among groups at high risk of developing this disease.

Association Between Baloxavir Marboxil Prescription for Children with Influenza B Infections and Short-Term Healthcare Consumption in Japan During the 2018-2019 Influenza Season.

Baloxavir marboxil is an anti-influenza medication that was newly introduced into clinical practice in 2018. Baloxavir might be more beneficial than neuraminidase inhibitors (NAIs), as suggested by a subgroup analysis of a clinical trial. Although the association between baloxavir prescription and healthcare use pertains mainly to influenza A, few studies have investigated the association in influenza B. We evaluated the healthcare utilization of children (0-15 years old) treated with either baloxavir or NAIs between December 2018 and May 2019 using claims records in Japan. The primary endpoint was the composite of medical resource utilization, including hospitalization, antibiotic use, laboratory tests, radiological images, and fluid replacement therapy, over 1-9 days after antiviral prescription. Secondary outcomes representing each single outcome in the composite were examined. Subgroup analyses comparing baloxavir with each NAI were also performed. Of 4490 patients with influenza B who received antiviral treatment, 51.6% were male, and the median age was 8 years old. Baloxavir was prescribed for 29.4% of the population, and NAIs were prescribed for 70.6%. In the total cohort, 49.3% of patients had any comorbidity related to complicated influenza infection. Concerning the composite endpoint, baloxavir prescription was not associated with a risk of subsequent medical resource use (adjusted odds ratio 1.11; 95% confidence interval 0.90-1.38; P = 0.34). Secondary outcomes and subgroup analyses showed similar results to the primary outcome. In a single-year comparative study in Japan, baloxavir prescription for influenza B was not associated with less healthcare consumption than NAIs within 9 days of treatment.

Predictors of Influenza Vaccination in Early Rheumatoid Arthritis 2017-2021: Results From the Canadian Early Arthritis Cohort.

ObjectiveAdults with rheumatoid arthritis (RA) are at a higher risk for infections, including influenza and related complications. We identified influenza vaccination coverage in adults newly diagnosed with RA and examined sociodemographic RA characteristics and attitudes associated with vaccination.MethodsWe used data from patients enrolled in the Canadian Early Arthritis Cohort between September 2017 and February 2021. At enrollment, participants reported their vaccination status in the previous year and completed the Beliefs About Medicines Questionnaire (BMQ). Clinical data were obtained from medical records. Logistic regression was used to identify predictors of vaccination in the year after RA diagnosis.ResultsThe baseline analytic sample of 431 patients were mostly White (80%) women (67%) with a mean age of 56 (SD 14) years. Prediagnosis, influenza vaccine coverage was 38%, increasing to 46% post diagnosis in the longitudinal sample (n = 229). Participants with previous influenza vaccination (odds ratio [OR] 15.33; 95% confidence interval [CI] 6.37‐36.90), on biologics or JAKs (OR 5.42; 95% CI 1.72‐17.03), and with a higher change in BMQ Necessity‐Concerns Differential scores (OR 1.08; 95% CI 1.02‐1.15) had greater odds, whereas women (OR 0.32; 95% CI 0.14‐0.71), participants with a non‐White racial background (OR 0.13; 95% CI 0.04‐0.51), and participants currently smoking (OR 0.09; 95% CI 0.02‐0.37) had lower odds of influenza vaccine coverage.ConclusionInfluenza vaccination coverage in patients with early RA remains below national targets in adults living with a chronic condition. Discussing vaccine history and medication attitudes at initial clinic visits with new patients with RA may enhance vaccine acceptance and uptake.

Clinical characteristics and outcomes of mixed virus or bacterial infection in children with laboratory-confirmed influenza infection

This study investigated the demographic characteristics and influenza complications of paediatric patients and explored the association of different influenza virus types and viral and bacterial coinfections with disease severity. This retrospective cohort study used data collected in 2010-2016 from the Chang Gung Research Database (CGRD), the largest collection of multi-institutional electronic medical records in Taiwan. Data were retrieved for children aged 0-18 years with laboratory-confirmed influenza. We extracted and analysed the demographic characteristics and the data on clinical features, complications, microbiological information, and advanced therapies of each case. We identified 6193 children with laboratory-confirmed influenza, of whom 1964 (31.7%) were hospitalised. The age of patients with influenza A infection was lower than that of patients with influenza B (4.48 vs. 6.68, p<0.001). Patients with influenza B infection had a higher incidence of myositis or rhabdomyolysis (4.4%, p<0.001) and a higher need for advanced therapies (OR, 1.96; 95% CI, 1.32-2.9, p<0.001). In addition to bacterial (OR, 9.07; 95% CI, 5.29-15.54, p<0.001) and viral coinfection (OR, 7.73; 95% CI, 5.4-11.07, p<0.001), dual influenza A and B infection was also a risk factor for influenza complications (OR, 2.13; 95% CI, 1.47-3.09, p<0.001). Dual influenza A and B infection and bacterial coinfection can contribute to influenza complications. Early recognition of any influenza complication is critical for the timely initiation of organ-specific advanced therapies to improve influenza-associated outcomes.

Effects of Influenza Vaccination in Patients with Interstitial Lung Diseases: An Epidemiological Claims Data Analysis

RationaleVaccination is the most effective protection against influenza. Patients with interstitial lung diseases (ILDs) represent a high-risk group for influenza complications. Thus, yearly influenza vaccination is recommended, but evidence on its effects is sparse.ObjectivesThis study aimed to compare all-cause mortality and all-cause and respiratory-related hospitalization between vaccinated and unvaccinated patients with ILD.MethodsUsing data from the largest German statutory health insurance fund (about 27 million insurees in 2020), we analyzed four influenza seasons from 2014–2015 to 2017–2018 and compared vaccinated with unvaccinated patients with ILD. Starting from September 1 of each year, we matched vaccinated and unvaccinated patients in a 1:1 ratio using a rolling cohort design. Mortality and hospitalization were compared with Kaplan-Meier plots, and effects were calculated during the influenza season (in season) with risk ratios.ResultsBoth the vaccinated and the unvaccinated cohorts included 7,503 patients in 2014–2015, 10,318 in 2015–2016, 12,723 in 2016–2017, and 13,927 in 2017–2018. Vaccination rates were low at 43.2% in season 2014–2015 and decreased over time to 39.9% in season 2017–2018. The risk ratios for all-cause mortality were 0.79 (95% confidence interval [CI], 0.65–0.97; P = 0.02) in season 2014–2015, 0.66 (95% CI, 0.54–0.80; P < 0.001) in 2015–2016, 0.89 (95% CI, 0.76–1.04; P = 0.15) in 2016–2017, and 0.95 (95% CI, 0.81–1.12; P = 0.57) in 2017–2018. The effects on all-cause hospitalization and respiratory-related hospitalization were similar in all seasons.ConclusionsAlthough an unequivocally beneficial impact of influenza vaccination in patients with ILD could not be demonstrated, we observed promising results regarding avoidance of all-cause mortality in half of the seasons observed. Given the low vaccination rates, further efforts are necessary to improve vaccination rates in patients with ILD.

Associated virus-bacterial vaccine based on seasonal LAIV and S. pneumoniae chimeric peptide provide protection against post-influenza pneumococcal infection in mouse model

ABSTRACT Severe influenza complications are often caused by Streptococcus pneumoniae infection, which presents the most common cause of community-acquired pneumonia. We evaluated in a mouse model an associated virus-bacterial vaccine based on seasonal live influenza vaccines (LAIV) and S. pneumoniae chimeric protein comprising flagellin (PSPF). Intranasal immunization of mice with a complex of trivalent LAIV and PSPF caused an increased release of early cytokines in the lungs of mice. The immunogenicity of LAIV and PSPF in the associated vaccine composition was sometimes decreased compared to each vaccine preparation alone. Nevertheless, only vaccination of mice with LAIV+PSPF significantly reduced lethality and the bacterial load in the lungs in a model of post-influenza bacterial pneumonia. The study of the interactions of influenza viruses with bacterial peptides is important during the development of associated virus-bacterial vaccines intended for the prevention of severe post-influenza bacterial complications.

Consideration on implementation of co-administration of Seasonal Influenza and COVID-19 vaccines during pandemic in China

Influenza is an infectious respiratory disease caused by the influenza viruses. Older people, infants and people with underlying medical conditions could have a higher risk of severe influenza symptoms and complications. The co-infection of Coronavirus Diseases 2019 (COVID-19) with influenza viruses could lead to the complication of prevention, diagnosis, control, treatment, and recovery of COVID-19. Influenza vaccine and COVID-19 vaccine overlapped in target populations, vaccination time, and inoculation units. Although there was insufficient evidence on the immunogenicity and safety of co-administration of influenza vaccine and COVID-19 vaccine, World Health Organization and some countries recommended co-administration of inactivated influenza vaccine and COVID-19 vaccine. This review summarized domestic and international vaccination policies and research progress, and put forward corresponding suggestions in order to provide scientific support for the formulation of vaccination strategy on seasonal influenza vaccine and COVID-19 vaccine.

Evaluating Confounding Control in Estimations of Influenza Antiviral Effectiveness in Electronic Health Plan Data.

Observational studies of oseltamivir use and influenza complications could suffer from residual confounding. Using negative control risk periods and a negative control outcome, we examined confounding control in a health-insurance-claims-based study of oseltamivir and influenza complications (pneumonia, all-cause hospitalization, and dispensing of an antibiotic). Within the Food and Drug Administration's Sentinel System, we identified individuals aged ≥18 years who initiated oseltamivir use on the influenza diagnosis date versus those who did not, during 3 influenza seasons (2014-2017). We evaluated primary outcomes within the following 1-30 days (the primary risk period) and 61-90 days (the negative control period) and nonvertebral fractures (the negative control outcome) within days 1-30. We estimated propensity-score-matched risk ratios (RRs) per season. During the 2014-2015 influenza season, oseltamivir use was associated with a reduction in the risk of pneumonia (RR = 0.72, 95% confidence interval (CI): 0.70, 0.75) and all-cause hospitalization (RR = 0.54, 95% CI: 0.53, 0.55) in days 1-30. During days 61-90, estimates were near-null for pneumonia (RR = 1.04, 95% CI: 0.95, 1.15) and hospitalization (RR = 0.94, 95% CI: 0.91, 0.98) but slightly increased for antibiotic dispensing (RR = 1.14, 95% CI: 1.08, 1.21). The RR for fractures was near-null (RR = 1.09, 95% CI: 0.99, 1.20). Estimates for the 2016-2017 influenza season were comparable, while the 2015-2016 season had conflicting results. Our study suggests minimal residual confounding for specific outcomes, but results differed by season.

Етіотропна противірусна терапія ГРІ та грипу

Наведено досвід ведення гострих респіраторних інфекцій (ГРІ), грипу в 2009–2016 рр., перелік інфекційних і неінфекційних ускладнень ГРІ, грипу, об’єктивних досліджень і показань до госпіталізації. Основна стратегія лікування ГРІ, грипу полягає в застосуванні етіотропних противірусних препаратів (ЕПП) — осельтамівіру, занамівіру, Інгавірину. Зроблено висновок про необхідність раннього прийому ЕПП. Наведена дихальна підтримка при гострому ушкодженні легенів, гострому респіраторному дистрес-синдромі із застосуванням неінвазивної і інвазивної вентиляції легенів.

Особливості грипу сезону 2016 року в дітей

У 47 дітей, хворих на грип А/H1N1 pd Каліфорнія 2009, які знаходилися впродовж січня — лютого 2016 року на стаціонарному лікуванні в клініці кафедри дитячих інфекційних хвороб НМУ імені О.О. Богомольця — Київській міській дитячій клінічній інфекційній лікарні, була виявлена відсутність особливостей клінічної картини, характерних для цього штаму грипу і в цьому сезоні. У більшості хворих дитячого віку захворювання перебігає в середньотяжкій формі. Серед ускладнень грипу в дітей частіше спостерігаються пневмонія та енцефалічна реакція у вигляді судомного синдрому. Фонові захворювання дихальної, серцево-судинної, ендокринної, нервової системи та атопічні дерматити є несприятливою прогностичною ознакою перебігу грипу A/H1N1 pd Каліфорнія 2009 у дітей у сезоні 2016 року.

Современные клинико-лабораторные особенности течения гриппа у взрослых

Обследованы и пролечены 472 больных гриппом, из них у 72 пациентов рентгенологически диагностирована пневмония, 69 из которых были госпитализированы в отделение реанимации и интенсивной терапии киевской городской клинической больницы № 4. Проведен анализ клинико-лабораторных данных больных гриппом, вызванным вирусом гриппа А (H1N1). Пневмония — одно из самых частых осложнений гриппа, которое существенно влияет на прогноз. Показано, что прогностически неблагоприятными критериями являются: позднее обращение за медицинской помощью (5–6-е сутки заболевания), развитие острого респираторного дистресс-синдрома, повышение или снижение лейкоцитов в крови и наличие тяжелой сопутствующей патологии.

Клініко-лабораторні особливості перебігу грипу у дорослих хворих в епідсезон 2015-2016 рр.

Поява в XXI столітті вірусних інфекцій респіраторного тракту, що набули ознак емерджентних (SARS, грип А (Н5N1, H1N1), MERS-CoV) обумовлюють достатньо високий показник смертності. Непередбачуваність еволюції вірусів грипу А викликає неспокій у спеціалістів всього світу. Мета. Провести порівняльний аналіз клініко-лабораторних особливостей при грипі А (H1N1) у дорослих з розвитком ускладнень, а також оцінка ефективності призначеної стартової терапії при пневмоніях. Матеріали і методи. Обстежено та проліковано 472 хворих на грип, з них у 72 пацієнтів рентгенологічно діагностовано пневмонію, 69 з яких були госпіталізовані у відділення реанімації та інтенсивної терапії КМКЛ № 4. Проведено аналіз клініко-лабораторної картини грипу у дорослих, спричиненого вірусом грипу А (H1N1). Результати і обговорення. Пневмонія – одне з найчастіших ускладнень грипу, що суттєво впливає на прогноз. Показано, що прогностично несприятливими критеріями є: пізнє звернення за медичною допомогою (5 – 6 доба захворювання), розвиток гострого респіраторного дистрес-синдрому (ГРДС), підвищення чи зниження лейкоцитів у крові та наявність тяжкої супутньої патології. Висновки. Результати аналізу супутньої патології різних систем та органів у хворих з грипом А (H1N1) показують, що захворювання серцево-судинної, ендокринної та системи крові є фактором ризику не лише тяжкого перебігу, але й летального наслідку захворювання в молодому віці. З лікарських засобів на прогноз та ступінь тяжкості перебігу суттєво впливає – раннє призначення етіотропної терапії, а призначення Нуклексу в рекомендованих дозах значно зменшує розвиток інших ускладнень та скорочує терміни перебування в стаціонарі.

A Systematic Review of Influenza Epidemiology and Surveillance in the Eastern Mediterranean and North African Region.

Seasonal influenza represents a huge health burden, resulting in significant mortality and morbidity. Following the 2009 H1N1 pandemic, focus has been directed on the burden of influenza globally. Country and regional disease burden estimates play important roles in helping inform decisions on national influenza intervention programmes. Despite improvements in influenza surveillance following the 2009 pandemic, many opportunities remain unexplored in the Eastern Mediterranean and North African (EMNA) region, which has a high prevalence of patients with chronic disease and thus a population at high risk of influenza complications. We conducted a systematic literature review of Embase, Medline, Scopus and the Cochrane Database of Systematic Reviews from 1 January 1998 to 31 January 2020 covering the EMNA region with the aim to describe the epidemiology of influenza in the region and assess the influenza epidemiological surveillance research landscape. Relevant data on study characteristics, population, clinical/virology characteristics and epidemiology were extracted and summarised descriptively. Of the 112 studies identified for inclusion, 90 were conducted in the Eastern Mediterranean region, 19 in North Africa and three across the EMNA region. Data were reported on 314,058 laboratory-confirmed influenza cases, 96 of which were derived from surveillance systems. Amongst the surveillance studies, the percentage of positive cases reported ranged from 1% to 100%. The predominantly identified influenza strain was strain A; H1N1 was the most prominent circulating subtype. Typing was performed in approximately 75% and subtyping in 50% of studies, respectively. Data on those considered most at risk for influenza complications were collected in 21% of studies, highlighting a regional gap for these data. Our review reveals existing gaps in regional estimates of influenza health and economic burden, hospitalisation rates and duration, and highlights the need for robust and high-quality epidemiology data to help inform public health interventions.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40121-021-00534-3.

Assessment of knowledge and attitude toward influenza vaccinations within the adult population of Riyadh, Saudi Arabia.

The most cost-effective measure for preventing the infectious disease, influenza, is vaccination. The purpose of this research was to evaluate knowledge levels, familiarity, and attitude toward influenza and influenza vaccination of the Riyadh adult population. A cross-sectional study was carried out in Riyadh and data was collected between December 2017 and March 2018. Five hundred participants were interviewed in person using a closed-ended questionnaire. Participants comprised the general population, students, and healthcare workers (HCWs), and were recruited from shopping malls, parks, Princess Nourah Bint Abdulrahman University, and King Abdullah Bin Abdulaziz University Hospital. A pilot study was conducted among 15 participants from the general population, students, and HCWs who gave verbal consent. Participants were asked if they comprehended the questionnaire and whether they felt comfortable participating. Descriptive statistics were used to describe the sample. Statistical significance was determined using t-test for quantitative variables and Chi-square test for qualitative variables. Most participants in all groups had poor knowledge. The least informed was the general population (8.8%), followed by the students (11.8%), and the most aware were the HCWs (18.5%). The social media (35%) was the main source of participants' knowledge, followed by doctors and health educators in hospitals (33%). Only 15.6% of participants had been vaccinated this year. Even fewer (8.8%) stated that they took the vaccination every year. The most important reasons for getting vaccinated were the recommendations by the Ministry of Health or by their doctors (77.8% for each). The key barrier to vaccination was a lack of perceived benefit (the participants did not usually get influenza so they felt vaccination was unnecessary [66.2%]). About 34% of participants reported that they had the children in their families vaccinated. The main reason given was to protect their children from influenza complications (80.6%). Within the Riyadh adult population, there was both low compliance to take the influenza vaccinations owing to a lack of perceived benefit and insufficient knowledge of the risks of influenza.

Seasonal influenza vaccine awareness and factors affecting vaccination in Turkish Society.

Objective:Influenza vaccine reduces the burden of seasonal influenza and related complications. Potential vaccination barriers need to be identified to raise awareness and increase acceptance. We aimed to investigate the rates of seasonal influenza vaccination and the knowledge, opinions, and behaviours prevalent in Turkish society.Methods:The study among seven regions in Turkey was conducted from October-November 2018 in 28 family health centres, using a cross-sectional, descriptive design. The knowledge, opinions, and behaviours of participants regarding the influenza vaccine were obtained by family physicians through face-to-face interviews with participants.Results:A total of 3,492 people aged 10-97 years age range (median: 50 years) were included in the study. Over half of the participants (59.9%, n = 2093) were female. It was found that the percentage of participants who never received the influenza vaccine was 78.4%; only 13.4% were occasionally vaccinated, and 8.1% received regular annual vaccination. Influenza vaccination rates were higher in married people (p < 0.001), women (p = 0.005), patients with chronic lung and cardiovascular disease (p < 0.001), those over 65 years /nursing home residents (p < 0.001). Awareness of the vaccine’s benefit was higher in the group at high risk of influenza (p < 0.001).Conclusion:The rate of regular vaccination against influenza every year was insufficient, at 8.1%. Individuals’ insensitivity, insufficient knowledge, and attitudes toward influenza vaccination is a serious health problem for Turkish society. Barriers to influenza vaccination can be reduced by good communication between family physicians and their patients.

Surveillance for severe influenza and COVID-19 in patients admitted to sentinel Australian hospitals in 2020: the Influenza Complications Alert Network (FluCAN).

Influenza is a common cause of acute respiratory infection, and is a major cause of morbidity and mortality. Coronavirus disease 2019 (COVID-19) is an acute respiratory infection that emerged as a pandemic worldwide before the start of the 2020 Australian influenza season. This report summarises the epidemiology of hospitalisations with laboratory-confirmed influenza and COVID-19 during the 2020 influenza season in a sentinel surveillance system. The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance program that operates at sites in all jurisdictions in Australia. Influenza and COVID-19 cases were defined as patients hospitalised at sentinel hospitals and confirmed by nucleic acid detection. There were 448 patients with COVID-19 admitted between 16 March and 31 December 2020, and only 20 patients with influenza admitted between 1 April and 30 November 2020, to one of 22 FluCAN hospitals. Of the COVID-19 cases, 173 (39%) were > 65 years of age, 36 (8%) were children (< 16 years), 6 (1%) were Aboriginal and Torres Strait Islander peoples, 4 (1%) were pregnant and 289 (65%) had chronic comorbidities. COVID-19 hospital admissions peaked between weeks 13 and 15 (first wave) nationally, and again between weeks 31 and 35 (Victoria), with most admissions represented by those above 40 years of age. There was an unusually low number of hospital admissions with laboratory-confirmed influenza in this season, compared to recent seasons. This is likely to be due to effective public health interventions and international border closures as a result of a rise in COVID-19 respiratory infections and associated hospitalisations.

Evaluation of the peripheral blood T and B cell subsets and IRF-7 variants in adult patients with severe influenza virus infection.

Background and AimsInfluenza virus is one of the leading infections causing death among human being. Despite known risks, primary immune deficiency due to Interferon Regulatory Factor‐7 (IRF7) gene defect was reported as a possible cause of the risk factors for complicated influenza. We aimed to investigate the changes in peripheral T and B cell subsets in adult patients with severe seasonal influenza virus infection and the investigation of variants of IRF7 gene.MethodsIn this study, 32 patients, hospitalized due to influenza infection‐related acute respiratory failure were included.ResultsThe median age of the patients was 76 years (26‐96), and 13/32 (40.6%) were in the intensive care unit. Central memory Th, effector memory Th, TEMRA Th, cytotoxic T lymphocytes (CTL), central memory CTL of the patients were found to be increased, naive CTL were decreased. There was a significant increase in the percentage of effector memory Th, and a decrease in the percentage of naive CTL in patients ≥65 years‐old compared to patients <65 years old (P = .039, and P = .017, respectively). IRF7 gene analysis revealed two different nucleotide changes in three patients; c.535 A > G; p.Lys179Glu ( K179E ) and c584A > T; p.His195Leu ( H195L ), located in the fourth exon of the IRF7 gene.DiscussionThe increases in central and effector memory Th, central memory CTL and decrease of naive CTLs may be secondary to the virus infection. K179E (rs1061502) and H195L (rs139709725) variants were not reported to be related with susceptibility to an infection yet. It is conceivable to investigate for novel variants in other genes related to antiviral immunity.

1444. Influenza Surveillance in the Veterans Health Administration (VHA): 2020-2021 Season

BackgroundVeterans Health Administration’s (VHA) large elderly population is at higher risk for influenza complications, including hospitalization and death. Herein we summarize VHA’s national annual surveillance data for seasonal influenza activity and vaccinations.MethodsInfluenza telephone triage, influenza-like-illness (ILI) encounters and antiviral prescriptions plus outpatient visits, laboratory testing, hospitalizations and deaths for influenza were obtained from VHA data sources (9/27/20-5/22/21) and compared to prior years and CDC FluView data. Influenza vaccinations were captured from 8/1/2020. Vaccination rates were calculated based on VHA users during the fiscal year. ResultsSurveillance metrics are presented (Table). Vaccinations were decreased and ILI was below average (0.3%-0.7% per week). Activity was highest 2020 Weeks 46-47 but remained low the entire season with no distinct peak seen, matching national influenza activity (Fig. 1). Testing revealed 161 influenza positives from 440,553 tests performed (0.04%). Hospitalizations among laboratory-confirmed cases were similar to the prior season (16% vs 17%). Median length of stay (6 days) and deaths (17, 12%) were increased over prior seasons. Among 15 deaths where results were available, 4 had Influenza A, 10 had Influenza B and 1 had Influenza A+B. Nine were co-infected with COVID-19. Total influenza positives, outpatient visits, hospitalizations and antiviral use were extremely low compared to all prior season where national VHA data has been analyzed (Table, Fig. 2). ConclusionOverall, influenza vaccination levels were decreased although percent receiving high-dose formulation was stable. Despite lower vaccination rates, the 2020-21 influenza season was of historically low activity, even with markedly increased testing performed in the setting of multiplex tests for influenza with COVID-19. Deaths were primarily seen with Influenza B and among those co-infected with COVID-19. This may also have contributed to increased length of stay. VHA influenza activity continues to track closely with national CDC data and may have been impacted by mitigation measures used to contain COVID-19, which were likely effective in curbing influenza activity. Disclosures All Authors: No reported disclosures