High Risk For Influenza Complications Research Articles

898. Influenza Surveillance in the US Veterans Health Administration (VHA): 2022-2023 Season

Abstract Background Influenza causes seasonal epidemics with substantial morbidity and mortality. Veterans 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 influenza activity and vaccinations. Methods Influenza-like-illness (ILI) as well as influenza-coded outpatient visits and hospitalizations, laboratory testing, and antivirals were obtained from VHA data sources (10/2/2022-4/22/23) and compared to prior years and CDC data. Vaccinations were captured starting 8/1/2022, with rates calculated based on VHA users in each fiscal year. Influenza RT-PCR positive respiratory samples underwent whole genome sequencing (WGS) to analyze clade and antiviral resistance. Results Surveillance metrics are presented (Table). Vaccinations were decreased compared to 2021-22, but the used of adjuvanted vaccine was increased. Weekly ILI ranged from 0.4%-1.4% in primary/urgent care settings. Activity was highest for 2022 Week 48, matching national influenza trends (Fig.1). Testing found 23,297 influenza positives of 457,020 tests performed (5.1%). Median length of stay (3 days) for hospitalized patients and deaths (127, 3%) were stable. Among 115 deaths where influenza type was available, 110 had Influenza A and 5 Influenza B. Following two low activity seasons, total influenza positives, outpatient visits, and hospitalizations during 2022-23 tracked closer to seasons prior to the COVID-19 pandemic (Table, Fig.2). 411 samples (in 16 states) were sequenced (410 Flu A: 136 H1, 274 H3; 1 B/Victoria), representing 12 subclades, which aligned with CDC reporting. No drug resistance mutations were found (Fig.3). Conclusion For 2022-23, influenza vaccinations in VHA dropped but percent vaccinated was stable. For the first time, over half of VHA-administered vaccines were adjuvanted formulation. The influenza season was notable for an earlier than usual peak (late Nov/early Dec), with overall increased activity compared to the prior two seasons. Testing for influenza during 2022-23 season was decreased but remained higher than pre-COVID-19 pandemic testing levels. VHA influenza activity and WGS analysis tracks closely with national CDC reporting. Disclosures All Authors: No reported disclosures

Trends in Outpatient Influenza Antiviral Use Among Children and Adolescents in the United States.

Influenza antivirals improve outcomes in children with duration of symptoms <2 days and those at high risk for influenza complications. Real-world prescribing of influenza antivirals in the pediatric population is unknown. We performed a cross-sectional study of outpatient and emergency department prescription claims in individuals <18 years of age included in the IBM Marketscan Commercial Claims and Encounters Database between July 1, 2010 and June 30, 2019. Influenza antiviral use was defined as any dispensing of oseltamivir, baloxavir, or zanamivir. The primary outcome was the rate of antiviral dispensing per 1000 enrolled children. Secondary outcomes included antiviral dispensing per 1000 influenza diagnoses and inflation-adjusted costs of antiviral agents. Outcomes were calculated and stratified by age, acute versus prophylactic treatment, influenza season, and geographic region. The analysis included 1 416 764 unique antiviral dispensings between 2010 and 2019. Oseltamivir was the most frequently prescribed antiviral (99.8%). Dispensing rates ranged from 4.4 to 48.6 per 1000 enrolled children. Treatment rates were highest among older children (12-17 years of age), during the 2017 to 2018 influenza season, and in the East South Central region. Guideline-concordant antiviral use among young children (<2 years of age) at a high risk of influenza complications was low (<40%). The inflation-adjusted cost for prescriptions was $208 458 979, and the median cost ranged from $111 to $151. There is wide variability and underuse associated with influenza antiviral use in children. These findings reveal opportunities for improvement in the prevention and treatment of influenza in children.

Recommendations for Prevention and Control of Influenza in Children, 2023-2024.

This statement updates the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2023-2024 influenza season. A detailed review of the evidence supporting these recommendations is published in the accompanying technical report (www.pediatrics.org/cgi/doi/10.1542/peds.2023-063773). The American Academy of Pediatrics recommends annual influenza vaccination of all children without medical contraindications starting at 6 months of age. Children are at risk for hospitalization and death from influenza. Influenza vaccination is an important strategy for protecting children and the broader community, as well as reducing the overall burden of respiratory illnesses when other viruses are cocirculating. Any licensed influenza vaccine appropriate for age and health status can be administered, ideally as soon as possible in the season, without preference for one product or formulation over another. Antiviral treatment of influenza is recommended for children with suspected (eg, influenza-like illness [fever with either cough or sore throat]) or confirmed influenza who are hospitalized, have severe or progressive disease, or have underlying conditions that increase their risk of complications of influenza, regardless of duration of illness. Antiviral treatment should be initiated as soon as possible. Antiviral treatment may be considered in the outpatient setting for symptomatic children with suspected or confirmed influenza disease who are not at high risk for influenza complications, if treatment can be initiated within 48 hours of illness onset. Antiviral treatment may also be considered for children with suspected or confirmed influenza disease whose siblings or household contacts either are younger than 6 months or have a high-risk condition that predisposes them to complications of influenza. Antiviral chemoprophylaxis is recommended for the prevention of influenza virus infection as an adjunct to vaccination in certain individuals, especially exposed children who are at high risk for influenza complications but have not yet been immunized or those who are not expected to mount an effective immune response.

Immunogenicity and safety of influenza vaccine in patients with lung cancer receiving immune checkpoint inhibitors: A single-center prospective cohort study

IntroductionPatients with lung cancer have a high risk of influenza complications. International guidelines recommend annual influenza vaccination for patients with cancer. Immune checkpoint inhibitors (ICIs) are progressively used to treat lung cancer. Data regarding immunogenicity and safety of influenza vaccine are limited in patients with lung cancer receiving ICIs; therefore, we conducted this single-center, prospective observational study in the Japanese population. MethodsPatients with lung cancer receiving ICIs and influenza immunization were enrolled. Blood samples were collected from patients for serum antibody titer measurement pre- and 4 ± 1 weeks post-vaccination. The primary endpoint was seroprotection rate (sP) at 4 ± 1 weeks post-vaccination. The secondary endpoints were geometric mean titer (GMT), mean fold rise, seroresponse rate (sR), seroconversion rate (sC), and immune-related adverse events (irAEs), defined as adverse effects caused by ICI administration, 6 months post-vaccination. ResultsInfluenza vaccination in the 23 patients included in the immunogenicity analyses significantly increased GMT for all strains, and sP, sR, and sC were 52%–91%, 26%–39%, and 26%–35%, respectively. In the 24 patients included in the safety analyses, 7 (29%) and 5 (21%) patients exhibited systemic and local reactions, respectively. Only one patient (4%) (hypothyroidism, grade 2) showed post-vaccination irAEs. ConclusionsOverall, influenza vaccination in patients with lung cancer receiving ICIs showed acceptable immunogenicity and safety, thus supporting annual influenza vaccination in this population.

A Prospective Cohort Study on Pregnancy Outcomes of Persons Immunized with a Seasonal Quadrivalent Inactivated Influenza Vaccine during Pregnancy.

This US-based, prospective observational cohort study evaluated the safety of a quadrivalent inactivated influenza vaccine (IIV4; Afluria Quadrivalent) in pregnant persons immunized over four influenza seasons between 2017 and 2021. Pregnancy outcomes included live birth, stillbirth, spontaneous abortion, and elective termination. Infant events of interest were major congenital malformations (MCMs), preterm birth (<37 weeks gestational age), and low birth weight (LBW). Data were descriptive; prevalence point estimates were reported with 95% confidence intervals (CI). A total of 483 pregnant persons were given IIV4 and evaluated; 477 (98.8%) reported a live birth, and there were 2 stillbirths, 4 spontaneous abortions, and no elective terminations or maternal deaths. The prevalence rates of infant events were as follows: preterm birth, 7.2% (upper 95% CI, 9.6%); LBW, 5.4% (upper 95% CI, 7.4%); and MCMs, 0.8% (upper 95% CI, 1.9%). Point estimates and upper 95% CIs of the observed prevalence rates were lower than or similar to background prevalence in the general US population. Our findings suggest no evidence of a safety concern with vaccinating this group at high risk of influenza complications and are consistent with published data from databases and surveillance systems that monitor the safety of influenza vaccines in pregnant persons.

Recommendations for Prevention and Control of Influenza in Children, 2022-2023.

This statement updates the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2022-2023 influenza season. A detailed review of the evidence supporting these recommendations is published in the accompanying technical report (http://www.pediatrics.org/cgi/doi/10.1542/peds.2022-059275). The American Academy of Pediatrics recommends annual influenza vaccination of all children without medical contraindications starting at 6 months of age. Influenza vaccination is an important strategy for protecting children and the broader community, as well as reducing the overall burden of respiratory illnesses when other viruses, including severe acute respiratory syndrome-coronavirus 2, are cocirculating. Any licensed influenza vaccine appropriate for age and health status can be administered, ideally as soon as possible in the season, without preference for one product or formulation over another. Antiviral treatment of influenza with any US Food and Drug Administration-approved, age-appropriate influenza antiviral medication is recommended for children with suspected or confirmed influenza who are hospitalized, have severe or progressive disease, or have underlying conditions that increase their risk of complications of influenza, regardless of duration of illness. Antiviral treatment should be initiated as soon as possible. Antiviral treatment may be considered in the outpatient setting for symptomatic children with suspected or confirmed influenza disease who are not at high risk for influenza complications, if treatment can be initiated within 48 hours of illness onset, and for children with suspected or confirmed influenza disease whose siblings or household contacts either are younger than 6 months or have a high-risk condition that predisposes them to complications of influenza. Antiviral chemoprophylaxis is recommended for the prevention of influenza virus infection as an adjunct to vaccination in certain individuals, especially exposed children who are at high risk for influenza complications but have not yet been immunized or who lack a sufficient immune response.

Guideline-Concordant Antiviral Treatment in Children at High Risk for Influenza Complications.

National guidelines recommend antiviral treatment for children with influenza at high risk for complications regardless of symptom duration. Little is known about concordance of clinical practice with this recommendation. We performed a cross-sectional study of outpatient children (aged 1-18 years) at high risk for complications who were diagnosed with influenza during the 2016-2019 influenza seasons. High-risk status was determined using an existing definition that includes age, comorbidities, and residence in a long-term care facility. The primary outcome was influenza antiviral dispensing within 2 days of influenza diagnosis. We determined patient- and provider-level factors associated with guideline-concordant treatment using multivariable logistic regression. Of the 274 213 children with influenza at high risk for influenza complications, 159 350 (58.1%) received antiviral treatment. Antiviral treatment was associated with the presence of asthma (aOR, 1.13; 95% confidence interval [CI], 1.11-1.16), immunosuppression (aOR, 1.10; 95% CI, 1.05-1.16), complex chronic conditions (aOR, 1.04; 95% CI, 1.01-1.07), and index encounter in the urgent care setting (aOR, 1.3; 95% CI, 1.26-1.34). Factors associated with decreased odds of antiviral treatment include age 2-5 years compared with 6-17 years (aOR, 0.95; 95% CI, .93-.97), residing in a chronic care facility (aOR, .61; 95% CI, .46-.81), and index encounter in an emergency department (aOR, 0.66; 95% CI, .63-.71). Among children with influenza at high risk for complications, 42% did not receive guideline-concordant antiviral treatment. Further study is needed to elucidate barriers to appropriate use of antivirals in this vulnerable population.

Implementation of a Military Emergency Department Influenza Vaccination Program: Lessons from Failure.

ABSTRACTIntroductionInfluenza infection in the United States results in hundreds of thousands of hospitalizations and 12,000 to 60,000 yearly deaths. Influenza season sees a sharp increase in emergency department (ED) patients nationwide, as primary care offices become overwhelmed. Because the ED is unique in its reach of underserved communities, ED vaccination programs can help maximize the number of people protected by vaccination. Influenza vaccination is one of the only vaccines that occurs yearly; therefore, successes with ED distribution of the influenza vaccine can potentially be translated into efforts of vaccinating the U.S. population more efficiently against other viral illnesses, such COVID-19. There has also not been a previous description in the literature of a vaccination program being used in a military setting. The original purpose of this study was to measure the effect of an ED vaccination program on our vaccine penetration and ED length of stay as well as to analyze the impact of provider education on vaccine uptake on vaccine refusal.MethodsThis was an observational, quality improvement project in the Wright-Patterson Medical Center Emergency Department evaluating an influenza vaccination program set to last from October 1, 2020 to April 1, 2021. Patients were to be surveyed to assess prior vaccination status, identify those at high risk for influenza complications, and to measure the effects of point-of-care education on vaccine acceptance. Separate measurements included average ED length of stay and the study’s impact on how quickly the base population could be vaccinated.ResultsThe effort was determined no longer feasible on November 20, 2020 because of the significant barriers. Although no data were gathered, we were able to glean important information that is vital in future efforts to implement ED-based vaccination programs. Reasons for program failure were multi-factorial, but were mainly attributed to rapid implementation, issues with Pyxis ordering and vaccine shipments, and vaccine storage capacity. The program also lacked a multidisciplinary implementation team of nurses and technicians, which could have better anticipated critical barriers.ConclusionInfluenza has caused multiple worldwide pandemics, contributed to countless deaths, and continues to be a challenge. ED-based influenza vaccination programs have been trialed to augment the primary care system in their effort to prevent deaths from influenza. The literature has shown that these programs are cost-effective and efficacious, but significant barriers have stunted their widespread utilization. Examining the rapid implementation and failure of this program highlights the importance of implementation models, process and barrier mapping, and proper operationalization. It is also the first such program that has been trialed in a military treatment facility. In consideration of the recent pandemic, successful ED-based vaccination programs can also offer a model for additional dissemination of other vaccines, such as the COVID-19 vaccine.

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.

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

Annals for Educators - November 2021.

Annals for Educators - November 2021.

Recommendations for Prevention and Control of Influenza in Children, 2021-2022.

This statement updates the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2021–2022 influenza season. A detailed review of the evidence supporting these recommendations is published in the accompanying technical report.1 The American Academy of Pediatrics recommends annual influenza immunization of all children without medical contraindications, starting at 6 months of age. Influenza vaccination is an important intervention to protect vulnerable populations and reduce the burden of respiratory illnesses during circulation of severe acute respiratory syndrome coronavirus 2, which is expected to continue during the 2021–2022 influenza season. Any licensed, recommended, age-appropriate vaccine available can be administered, without preference for one product or formulation over another. Antiviral treatment of influenza with any licensed, recommended, age-appropriate influenza antiviral medication is recommended for children with suspected or confirmed influenza who are hospitalized, have severe or progressive disease, or have underlying conditions that increase their risk of complications of influenza. Antiviral treatment may be considered for any previously healthy, symptomatic outpatient not at high risk for influenza complications, in whom an influenza diagnosis is confirmed or suspected, if treatment can be initiated within 48 hours of illness onset and for children whose siblings or household contacts either are younger than 6 months or have a high-risk condition that predisposes them to complications of influenza.Children consistently have the highest attack rates of influenza in the community during seasonal influenza epidemics. Children play a pivotal role in the transmission of influenza virus infection to household and other close contacts and can experience substantial morbidity, including severe or fatal complications from influenza infection.2 Children younger than 5 years, especially those younger than 2 years, and children with certain underlying medical conditions are at increased risk of hospitalization and complications attributable to influenza (Table 1).2 School-aged children bear a large influenza disease burden and are more likely to seek influenza-related medical care compared with healthy adults.2,3 Reducing influenza virus transmission among children decreases the burden of childhood influenza and transmission of influenza virus to household contacts and community members of all ages.2,3 Influenza vaccination is particularly important during the severe acute respiratory syndrome coronavirus 2 pandemic to reduce the burden of respiratory illnesses and hospitalizations and preserve the capacity of the health care infrastructure. The American Academy of Pediatrics (AAP) recommends routine influenza vaccination and antiviral agents for the prevention and treatment of influenza in children, respectively. This policy statement summarizes updates and recommendations for the 2021–2022 influenza season. An accompanying technical report provides further detail regarding recent influenza seasons, influenza vaccine effectiveness (VE), detailed updates of inactivated influenza vaccines (IIVs) and live attenuated influenza vaccines (LAIVs), influenza vaccination coverage, vaccine implementation, and timing of vaccination and duration of protection.1Children and adolescents with certain underlying medical conditions have a high risk of complications from influenza (Table 1). Although universal influenza vaccination is recommended for everyone starting at 6 months of age, emphasis should be placed in ensuring that high-risk and vulnerable children and their household contacts and caregivers receive annual influenza vaccine.The seasonal influenza vaccines licensed for children and adults for the 2021–2022 season are shown in Table 2. More than one product may be appropriate for a given patient, and vaccination should not be delayed to obtain a specific product.All 2021–2022 seasonal influenza vaccines will be quadrivalent and contain the same influenza strains as recommended by the World Health Organization and the US Food and Drug Administration Vaccines and Related Biological Products Advisory Committee for the Northern Hemisphere.4,5 Both influenza A(H1N1) and A(H3N2) components are different in this season’s vaccine. The B components are unchanged. The influenza A strains may be different for egg-based versus cell- or recombinant-based vaccines on the basis of their optimal characteristics for each platform, but all are matched to the strains expected to circulate in the 2021–2022 season.The contraindications and precautions for the use of IIV and LAIV are described in Table 3, and further details are provided in the technical report.1 Anaphylactic and severe allergic reactions to any influenza vaccine are contraindications to vaccination. The AAP recommends that children who have had an allergic reaction after a previous dose of any influenza vaccine should be evaluated by an allergist to determine if future receipt of the vaccine is appropriate.Antivirals available for the treatment and prophylaxis of influenza in children are described in Table 4.Antiviral chemoprophylaxis is recommended after known or suspected influenza exposure in the following situations: Jennifer M. Frantz, MPH

Effectiveness of the Adjuvanted Influenza Vaccine in Older Adults at High Risk of Influenza Complications.

MF59®-adjuvanted trivalent inactivated influenza vaccine (aIIV3) and high-dose trivalent inactivated influenza vaccine (HD-IIV3) elicit an enhanced immune response in older adults compared to standard, quadrivalent inactivated influenza vaccines (IIV4). We sought to determine the relative vaccine effectiveness (rVE) of aIIV3 versus IIV4 and HD-IIV3 in preventing influenza-related medical encounters in this retrospective cohort study involving adults ≥65 years with ≥1 health condition during the 2017–2018 and 2018–2019 influenza seasons. Data were obtained from primary and specialty care electronic medical records linked with pharmacy and medical claims. Adjusted odds ratios (OR) were derived from an inverse probability of treatment-weighted sample adjusted for age, sex, race, ethnicity, geographic region, vaccination week, and health status. rVE was determined using the formula (% rVE = 1 − ORadjusted) × 100. Analysis sets included 1,755,420 individuals for the 2017–2018 season and 2,055,012 for the 2018–2019 season. Compared to IIV4, aIIV3 was 7.1% (95% confidence interval 3.3–10.8) and 20.4% (16.2–24.4) more effective at preventing influenza-related medical encounters in the 2017–2018 and 2018–2019 seasons, respectively. Comparable effectiveness was observed with HD-IIV3 across both seasons. Our results support improved effectiveness of aIIV3 vs IIV4 in a vulnerable population of older adults at high risk of influenza and its complications.

Pharmacy deserts and patients with breast cancer receipt of influenza vaccines

BackgroundYearly influenza vaccination is strongly recommended at age 65 and reimbursed by Medicare without copays or deductibles at pharmacies and clinical settings. Uptake is low among patients with a high risk for influenza complications and good access to specialist care, such as recent cancer survivors. We hypothesized that more accessible pharmacies could be associated with higher immunization uptake in such patients. ObjectivesTo determine whether pharmacy access is associated with influenza vaccination in subjects recently diagnosed with breast cancer, and whether this association differs by additional risk factors for influenza complications. MethodsWe examined a cohort of patients with stage 0-III breast cancer diagnosed 2011-2015 from the Surveillance, Epidemiology, and End Results–Medicare cancer registry. All retail pharmacies in the United States were identified, and pharmacy access was measured by assessing supply and demand in each census tract using a 2-stage floating catchment area approach that accounted for pharmacy driving distances recommended by the Centers for Medicare and Medicaid Services. We examined the association of pharmacy access with influenza vaccination after breast cancer diagnosis in regression models. ResultsMore than 11% of 45,722 patients with breast cancer lived in census tracts where no pharmacies were within recommended driving distances from the population-weighted tract center. Vaccination in the year after diagnosis was less likely for patients in these very low–access tracts (adjusted odds ratio 0.92 [95% CI 0.86–0.96]), black (0.55 [0.51–0.60]) and Hispanic (0.76 [0.70–0.83]) women, and Medicaid recipients (0.74 [0.69–0.79]). Vaccination was inversely associated with per capita income in the subject’s census tract, but there was no difference in the pharmacy effect by race, ethnicity, or census tract income. ConclusionVery low pharmacy access is associated with modest reductions in vaccination that could be useful for policy and planning regarding vaccinator resources and outreach.

Effectiveness of the Cell-Derived Inactivated Quadrivalent Influenza Vaccine in Individuals at High Risk of Influenza Complications in the 2018-2019 United States Influenza Season.

BackgroundHigher rates of influenza-related morbidity and mortality occur in individuals with underlying medical conditions. To improve vaccine effectiveness, cell-based technology for influenza vaccine manufacturing has been developed. Cell-derived inactivated quadrivalent influenza vaccines (cIIV4) may improve protection in seasons in which egg-propagated influenza viruses undergo mutations that affect antigenicity. This study aimed to estimate the relative vaccine effectiveness (rVE) of cIIV4 versus egg-derived inactivated quadrivalent influenza vaccines (eIIV4) in preventing influenza-related medical encounters in individuals with underlying medical conditions putting them at high risk of influenza complications during the 2018–2019 US influenza season.MethodsAn integrated dataset, linking primary care electronic medical records with claims data, was used to conduct a retrospective cohort study among individuals aged ≥4 years, with ≥1 health condition, vaccinated with cIIV4 or eIIV4 during the 2018–2019 season. Adjusted odds ratios (ORs) were derived using a doubly robust inverse probability of treatment-weighting (IPTW) model, adjusting for age, sex, race, ethnicity, geographic region, vaccination week, and health status. Relative vaccine effectiveness was estimated by (1 − OR) × 100 and presented with 95% confidence intervals (CIs).ResultsThe study cohort included 471 301 cIIV4 and 1 641 915 eIIV4 recipients. Compared with eIIV4, cIIV4 prevented significantly more influenza-related medical encounters among individuals with ≥1 health condition (rVE, 13.4% [95% CI, 11.4%–15.4%]), chronic pulmonary disease (rVE, 18.7% [95% CI, 16.0%–21.3%]), and rheumatic disease (rVE, 11.8% [95% CI, 3.6%–19.3%]).ConclusionsOur findings support the use of cIIV4 in individuals ≥4 years of age at high risk of influenza complications and provide further evidence supporting improved effectiveness of cIIV4 compared with eIIV4.

Identification of pathogens from the upper respiratory tract of adult emergency department patients at high risk for influenza complications in a pre-Sars-CoV-2 environment

The emergence of SARS-CoV-2 and subsequent COVID-19 pandemic highlights the morbidity and potential disease severity caused by respiratory viruses. To elucidate pathogen prevalence, etiology of coinfections and URIs from symptomatic adult Emergency department patients in a pre-SARS-CoV-2 environment, we evaluated specimens from four geographically diverse Emergency departments in the United States from 2013-2014 utilizing ePlex RP RUO cartridges (Genmark Diagnostics). The overall positivity was 30.1% (241/799), with 6.6% (16/241) coinfections. Noninfluenza pathogens from most to least common were rhinovirus/enterovirus, coronavirus, human metapneumovirus and RSV, respectively. Broad differences in disease prevalence and pathogen distributions were observed across geographic regions; the site with the highest detection rate (for both mono and coinfections) demonstrated the greatest pathogen diversity. A variety of respiratory pathogens and geographic variations in disease prevalence and copathogen type were observed. Further research is required to evaluate the clinical relevance of these findings, especially considering the SARS-CoV-2 pandemic and related questions regarding SARS-CoV-2 disease severity and the presence of co-infections.

Risk Factors for Pneumonia and Death in Adult Patients With Seasonal Influenza and Establishment of Prediction Scores: A Population-Based Study.

BackgroundSeasonal influenza remains a global health problem; however, there are limited data on the specific relative risks for pneumonia and death among outpatients considered to be at high risk for influenza complications. This population-based study aimed to develop prediction models for determining the risk of influenza-related pneumonia and death.MethodsWe included patients diagnosed with laboratory-confirmed influenza between 2016 and 2017 (main cohort, n = 25 659), those diagnosed between 2015 and 2016 (validation cohort 1, n = 16 727), and those diagnosed between 2017 and 2018 (validation cohort 2, n = 34 219). Prediction scores were developed based on the incidence and independent predictors of pneumonia and death identified using multivariate analyses, and patients were categorized into low-, medium-, and high-risk groups based on total scores.ResultsIn the main cohort, age, gender, and certain comorbidities (dementia, congestive heart failure, diabetes, and others) were independent predictors of pneumonia and death. The 28-day pneumonia incidence was 0.5%, 4.1%, and 10.8% in the low-, medium-, and high-risk groups, respectively (c-index, 0.75); the 28-day mortality was 0.05%, 0.7%, and 3.3% in the low-, medium-, and high-risk groups, respectively (c-index, 0.85). In validation cohort 1, c-indices for the models for pneumonia and death were 0.75 and 0.87, respectively. In validation cohort 2, c-indices for the models were 0.74 and 0.87, respectively.ConclusionsWe successfully developed and validated simple-to-use risk prediction models, which would promptly provide useful information for treatment decisions in primary care settings.

LB-2. Relative Effectiveness of aIIV3 versus IIV4 and HD-IIV3 In Preventing Influenza-Related Medical Encounters in Adults ≥65 Years of Age at High Risk for Influenza Complications During the U.S. 2017–2018 and 2018–2019 Influenza Seasons

BackgroundIndividuals with health conditions have shown higher rates of influenza-related morbidity and mortality compared to healthy individuals and are often prioritized for influenza vaccination. However, vaccination with egg-derived standard quadrivalent inactivated influenza vaccines (IIV4) has shown to be less effective in adults ≥65 years of age largely due to immunosenecence. Two enhanced vaccines, the MF59®-adjuvanted trivalent inactivated influenza vaccine (aIIV3) and a high-dose trivalent inactivated influenza vaccine (HD-IIV3), were developed to provide adults ≥65 years with increased protection. The objective of this study was to determine the relative vaccine effectiveness (rVE) of aIIV3 versus IIV4 and HD-IIV3 in preventing influenza-related medical encounters in high-risk adults ≥65 years.MethodsA retrospective cohort study was conducted among adults ≥65 years with ≥1 health condition with a record of receiving either aIIV3, IIV4 or HD-IIV3 in the 2017–18 or 2018–19 influenza seasons. Patient-level electronic medical records linked to pharmacy and medical claims were used to ascertain exposure, outcome and covariate information. The primary outcome was influenza-related medical encounters in primary care and hospital (ICD-10 codes J09*–J11*). Inverse probability of treatment weighting was used to obtain odds ratios (ORs) adjusted for age, sex, race, ethnicity, geographic region, comorbidities and week of vaccination for each health condition. rVE was determined using the formula (1-OR)*100 and reported with 95% confidence intervals (CI).ResultsOverall, 1,755,420 individuals with ≥1 health condition were included for analysis in the 2017–18 season and 2,055,012 individuals in the 2018–19 season. In both seasons, high-risk subjects who received aIIV3 had statistically significantly greater reduction in influenza-related medical encounters as compared to IIV4 (Table 1). Non-statistically significant estimates preclude definitive conclusions for comparisons with HD-IIV3.Table 1. Adjusted relative vaccine effectiveness (rVE) of aIIV3 versus comparators in high-risk patients in the 2017–2018 and 2018–2019 influenza seasons in the U.S. ConclusionThe results of this study support the use of aIIV3 in adults ≥65 years of age at high risk for influenza complications and provides further evidence supporting aIIV3 as an effective public health measure against influenza.Disclosures Lauren Fischer, M.A., Seqirus (Consultant) Dan O'Brien, BA, Seqirus (Consultant) Joseph Vasey, PhD, Seqirus (Consultant) Gregg C. Sylvester, MD, Seqirus (Employee) James A. Mansi, PhD, Seqirus (Employee)

1709. Influenza Surveillance in the U.S. Department of Veterans Affairs (VA): 2019-2020 Season

BackgroundVA conducts annual surveillance for seasonal influenza. VA’s large elderly population is at higher risk for influenza complications, including hospitalization and death. Herein we summarize VA’s 2019-20 national surveillance data for influenza activity and vaccinations.MethodsInfluenza telephone triage, influenza-like-illness (ILI) encounters and antiviral prescriptions plus outpatient visits, laboratory testing (antibody tests excluded), hospitalizations and deaths for influenza were obtained from VA data sources (9/29/19-5/16/20) and compared to prior seasons and national CDC FluView data. Influenza vaccinations were captured starting 8/1/2019. Vaccination rates were calculated based on VA users during the fiscal year.ResultsSurveillance metrics are presented (Table). ILI visits ranged from 0.9%-3.1% during the season. Influenza activity peaked during 2020 Weeks 6-7 and dropped rapidly beginning in Week 12, matching trends reported by CDC for influenza activity (Figure 1). Testing revealed 23,357 influenza positives out of 162,102 tests performed (14.4%). 17% of laboratory-confirmed influenza cases were hospitalized (compared to 23% during the prior season) with a median length of 3 days. Total influenza positives, telephone triage encounters, outpatient visits and antiviral use were higher than the prior season, whereas coded hospitalizations and deaths were fewer (Table, Figure 2).Table. VA Influenza Surveillance Measures, 2014-2015 through 2019-2020 Seasons. Figure 1. Comparison of select VA and CDC Influenza Indicators. Influenza positive laboratory tests and % positive (top) and influenza hospitalizations (bottom), by Season. Figure 2. Comparison of Key VA Influenza Indicators, by Season. ConclusionThe 2019-20 influenza season was of moderate severity when compared to prior seasons and continues to track well with national CDC data. Overall, vaccination levels have increased modestly and high-dose/adjuvanted vaccine administration increased from 6 to 26% of total vaccine given over the seasons evaluated. Influenza activity dropped precipitously after Week 12 even though testing for influenza remained high in the setting of COVID-19. This may have been influenced by widespread social distancing and masking measures adopted in response to COVID-19.Disclosures All Authors: No reported disclosures

Intravenous peramivir vs oral oseltamivir in high-risk emergency department patients with influenza: Results from a pilot randomized controlled study.

BackgroundPeramivir offers a single‐dose intravenous (IV) treatment option for influenza (vs 5‐day oral dosing for oseltamivir). We sought to compare outcomes of emergency department (ED) patients at high risk for influenza complications treated with IV peramivir vs oral oseltamivir.MethodsDuring the 2015‐16 and 2016‐17 influenza seasons, adult patients in two US EDs were randomized to either oral oseltamivir or IV peramivir treatment group. Eligibility included positive molecular influenza test; met CDC criteria for antiviral treatment; able to provide informed consent and agree to follow‐up assessment. Outcomes were measured by clinical end‐point indicators, including FLU‐PRO Score, Ordinal Scale, Patient Global Impression on Severity Score, and Karnofsky Performance Scale for 14 days. Non‐inferior t test was performed to assess comparative outcomes between the two groups.ResultsFive hundred and seventy‐five (68%) of 847 influenza‐positive patients were approached. Two hundred and eighty‐four met enrollment criteria and 179 were enrolled; of these 95 (53%) were randomized to peramivir, and 84 to oseltamivir. Average FLU‐PRO score at baseline was similar (peramivir: 2.67 vs oseltamivir: 2.52); the score decreased over time for both groups (day 5: peramivir: 1.71 vs oseltamivir: 1.62; day 10: peramivir: 1.48 vs oseltamivir: 1.37; day 14: peramivir: 1.40 vs oseltamivir: 1.33; all P < .05 for significantly non‐inferior). Influenza‐related complications were similar between two groups (All: peramivir: 31% vs oseltamivir: 21%, P > .05; pneumonia: peramivir: 11% vs oseltamivir: 14%, P > .05).ConclusionsClinical outcomes of influenza‐infected patients treated with single‐dose IV peramivir were comparable to those treated with oral oseltamivir, suggesting potential utility of peramivir for influenza‐infected patients in the ED.